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| Building Linux Virtual Private Networks |
Posted by
timothy
on 2002.02.27 8:30
Richard Miller contributed this review of New Riders' entry to the field
of VPN books. No suspense, he gives the book a big thumbs up -- read on below
for his reasoning, in particular a comparison to the previously available
alternatives.
Building Linux Virtual Private Networks
|
author |
Bri Hatch, Oleg Kolesnikov |
pages |
408 |
publisher |
New Riders |
rating |
10 |
reviewer |
Richard Miller |
ISBN |
1578702666 |
summary |
Finally, a VPN book you can use. |
Rants
I've been on the lookout for a good VPN book since
I first bought the O'Reilly VPN book in 1998. Yes, that book shattered my
long standing belief that O'Reilly could do no wrong. The technical descriptions
of VPN technologies were flawed and confusing, and they seemed to think that
the only usable VPN technologies were commercial products. They only showed
you implementations via screen shots of point-and-click GUI sessions. The
one potentially portable section describing PPP over SSH was practically
copyright infringement from the HOWTO, but with enough errors that they could
make the case they had never actually read it.
For a while the O'Reilly VPN book was the only one
out there. Then a few other publishers got into the mix. Unfortunately
their results were no better. I could never find a book that had both a
description of the protocols that would allow you to debug problems and implementation
details that weren't so vague that they could apply to the installation of
my washing machine. I must have bought half a dozen VPN books, all of which
were severly lacking in crucial aspects that would make them usable. I had
little stickies placed in them showing me which parts were correct and helpful,
and would flop between them all whenever I needed to do something, because
nothing got it all right.
Now I'm not here just to flame these other books, but
I must let you get an idea for how I was feeling, because only then can you
understand how much happier I am now. Now I can finally throw away all those
other books.
Building Linux VPNs was written by Bri Hatch (of Hacking Linux Exposed
fame) and Oleg Kolesnikov, and published by the New Riders, the same guys
who do the SANS publications. It's not as thick as you might expect, coming
in at 408 pages, but it's remarkably dense in a good way. No wasted space
for boring screen shots, instead concentrating on well tailored diagrams
when needed, code listings, and command line sessions.
Overview
Part one, the first two chapters, teaches you everything
you need to know about general VPN technology, and discusses all the VPN
issues you're going to face: various different network topologies you could
use, how to get your routing set up on both servers and clients, DNS setups,
how to use VPNs with firewalls (and where they could go) and more. These
are the issues that the trickiest to get right when actually setting up a
VPN, and something most other VPN books leave up to the reader to figure
out.
Part two discusses standard VPN protocols. The first
two chapters of this section discuss creating a VPN with PPP over SSH and
SSL. For those of us who have implemented PPP over SSH following the HOWTO
before, you'll remember how hackish it felt. The authors have come up with
a much more modular (you can have any number of VPNs easily) and secure (they
teach you how to set up your SSH keys or SSL certificates securely) method,
and provide you all the code to do it. Following the step-by-step instructions,
you could make a PPP over (SSH/SSL) VPN in about 30 minutes. Rock on.
They then dedicate two chapters to IPSec: one for the
description of the protocol itself (which definitely deserves a chapter)
and then one for the implementation of FreeS/WAN. IPSec is known to be a
difficult beast to ride, and they do a really great job of giving you the
information needed to get it right.
The last chapter of this part covers PPTP for both
server and client. I was shocked to see PPTP discussed in a Linux book,
but I guess the authors say it best when they said:
"There are times when you must support PPTP, either
because you are forced to connect to a server that only runs PPTP or because
you need to support remote Windows machines. In either of these cases, we
offer our deepest sympathies."
Part three discusses non-standard VPN protocols. In
the same detailed fashion, the authors devote three chapters to alternative
VPN technologies VTun, CIPE, and tinc. While these technologies do not have
IETF protocol drafts, they are nonetheless well defined, and work on multiple
Unix platforms.
Analysis
In this day and age of '2nd/3rd/4th Edition' it's good to see a book that really hit the nail on the head the first time. Building Linux Virtual Private Networks
has all the technical information you need to understand the protocols, set
up your networks, and troubleshoot, and has the implementation details to
get it all done almost entirely pain free.
It's extreemly easy to read, has a consistent style
and tone, and uses just the right amount of humor to keep you interested
in something that could be an extreemly boring technical topic.
One nice thing is that they defined their network early
in the book, and they implemented each separate VPN technology using the
same network, including host names, IP addresses, etc. This consistency
really pays off in clarity to the reader.
Beefs
There's a good bit of code in the book, which is a
great thing. They mention throughout that you can download the code online
at their website, but it doesn't seem to be there yet. Hopefully this will
get rectified. (You can still get a preview, though, at the book's official website. Good to see folks who don't blindly use ".com" for everything. )
Also, a lot of the software they discuss works on *BSD,
Solaris, some even on Windows. Why does every book need to include the magic
'L' word in the title nowadays?
Kudos.
You can purchase Building Linux VPNs from Fatbrain. Want to see your own review here? Just read the book review guidelines, then use Slashdot's handy submission form.
| |
Book Reviews |
Slashdot's book review section is brimming with reader-submitted commentary on interesting books.
Here's a
sampling of recent reviews -- read below for how you can add yours to the list.
For programmers, check out reviews of the Zope
Bible, Programming
Jabber and other specialized books.
If you're just trying to manage programmers, grumpy's review of Managing
Einsteins might be just what you're looking for. Meanwhile, keep the company afloat with
lessons learned from The
MouseDriver Chronicles and The
Bombast Transcripts.
Science buff? Read Tal Cohen's reaction to Rare
Earth, and Peter Wayner on Digital
Biology. Don't forget the grain of salt in Voodoo
Science, either.
His
Dark Materials is one of the many Science Fiction titles that Slashdot readers have
praised or panned for your pleasure.
And somewhere between Sci-Fi and reality are books like Flesh and
Machines, reporting from the intersection of yesterday's fiction and current
technology.
It's easy to submit your own reviews for consideration, too. Just read the Slashdot book review guidelines, and then use the web submission form.
Update: 20020427 12:50 by timothy
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The Fine Print:
The following comments are owned by whoever posted them.
We are not responsible for them in any way.
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Is it as good as New Riders' MySQL book? (Score:0)
by Anonymous Coward on 2002.02.27 8:36 (#3077649)
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New Riders' MySQL book is mighty fine; if this is half as good it'll be worth reading
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[ Parent
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beneath your current threshold.
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What's complicated about FreeSWAN? (Score:4, Interesting)
by Anonymous Coward on 2002.02.27 8:39 (#3077660)
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They have excellent documentation and they keep the documentation trees
for older versions online. Installation is as complicated as running a skript
and installing the recompiled kernel, if even that. I guess it never hurts
to have more documentation, but saying that IPSec is "a difficult beast to
ride" produces more awe than necessary.
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[ Parent
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Re:What's complicated about FreeSWAN? (Score:5, Insightful)
by Starship Trooper on 2002.02.27 8:49 (#3077724)
(User #523907 Info | http://www.geocities.com/tirnothy | Last Journal: 2002.06.19 20:41)
|
What's complicated about FreeSWAN?
Well,
a LOT. Not if you're deeply involved technically in the project, but if you
back out and take the perspective of someone who's never used a VPN, plenty.
A
lot of people don't even think about the fact that there's a separate protocol
field in IP, or that people run any IP protocol but UDP or TCP. Getting 50/51
through your existing firmware firewall can be a real trick. FreeSWAN requires
you to be able have the GNU Multi-Precision library installed for the crypto
calculations before you compile it. Unless your distro can with FreeSWAN, you have to recompile your kernel with modifications.
And,
like many tools, there's no single graphical GUI; unlike SAMBA's excellent
SWAT, there's nothing to lead you to ipsec.conf or ipsec.secrets. There's
a LOT of reading to be done.
Ok, so, for you or me, it's easy. Maybe
a day of reading tops. But compare that to the commercial world where an
application must install and be configured from a GUI in a few hours, and
FreeSWAN is... nearly a toy. It's unusable in a business environment. As
soon as you say "compile", a CTO is going to turn down your volume.
It's cool, but don't call it uncomplicated. That's part of it's coolness (-;
-- -- If you like Apple, then please press your right mouse button.
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[ Parent
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Re:What's complicated about FreeSWAN? (Score:3, Insightful)
by smcavoy on 2002.02.27 9:30 (#3077979)
(User #114157 Info | http://slashdot.org/)
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I use Freeswan in a production environment. I have Embedded Linux routers
using freeswan connecting to Linux boxes. They VPNs are relatively simple,
2 outgoing connections to central systems.
I did find there was a large learning curve at the beginning, but now it
takes 5 min to setup a new vpn tunnel. The systems have been extremely reliable.
I've never had a problem (other than net congestion) with keeping the tunnels
up. A lot of the tunnels have 80+ days of uptime. As for compiling, most
modern distros include IPSec (trustix, mandrake, etc.) or there are options
like Astaro. Having a CTO "turn down your volume" based on the fact that
you have to compile software, doesn't say anything about the quality or reliability
of the software, that's a personal decision by CTO not to use OSS. I do agree
it's not point and click, and that would be nice, but to say it's unusable
in a business environment is just untrue. It's not pretty but it works, and
works well. -- _________________
The best defense against logic is ignorance.
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Re:What's complicated about FreeSWAN? (Score:0)
by Anonymous Coward on 2002.02.27 9:54 (#3078169)
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How right you are. As a system admin that has always used windows or
dos. I am tring to change. I want to start using some Linux servers here,
but one of the things that I want to use is free/swan. It does seem great,
but as a 1 person IT department I have not found the time that I need to
read and understand the documentation on swan. Do I want a GUI Heck yes.
Do I still want access to the .conf file Heck yes. These problems are around
a lot in the Linux community. The people that have always used linux do see
it as hard and some dont want us new people to whine because it is not "dumb
down", but on the other hand they want all of us to switch to it. I dont
want to do away with the command line at all. I love it for a lot of what
I do, but when I want to make changes or try out some new tools I dont want
to have to spend 1-2 days reading ALL the docs just to know where to start.
Just my 2 cents. Let the flames begin!!!!
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Re:What's complicated about FreeSWAN? (Score:3, Insightful)
by disappear (jon@lasser.org) on 2002.02.27 10:03 (#3078246)
(User #21915 Info | http://www.tux.org/~lasser/)
|
one
of the things that I want to use is free/swan. It does seem great, but as
a 1 person IT department I have not found the time that I need to read and
understand the documentation on swan. Do I want a GUI Heck yes.
With security software in general, and VPN software in particular, that's
a very, very dangerous attitude: a GUI may fool you into thinking that you
understand what's going on when in reality you haven't a clue. With most
software, that's not an issue, but with security software, that can compromise
the very goal you're trying to achieve.
I dont want to do away with the command line at all. I love it
for a lot of what I do, but when I want to make changes or try out some new
tools I dont want to have to spend 1-2 days reading ALL the docs just to
know where to start.
How many days do you want to spend cleaning up after a security incident
that occurred because the GUI let you get away without spending two days
reading documentation? How much time will you save in the long run if every
time you save two days reading documentation you spend three days cleaning
up?
(We lose money on every item --- but we make it up in volume!)
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[ Parent
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Re:What's complicated about FreeSWAN? (Score:1)
by BeNude (benude@nospam.sss.org) on 2002.02.27 16:15 (#3081147)
(User #28969 Info | http://www.sss.org/texnude)
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I would disagree with you about the usefulness of a GUI to implement VPN's or firewalls.
First
of all, a GUI interface, if it is well-designed, can provide every bit as
much control over the underlying security behavior of a firewall as any command-line
interface. Furthermore, a GUI allows an administrator to spend less time
trying to deal with syntax, etc., and more time on building a ruleset that
is secure.
Someone who has done the reading and understands how firewalls and VPN's work will appreciate a GUI because of this.
For
those who don't fully understand how firewalls and VPN's work, a GUI at least
provides a reasonable learning environment and early attempts at a ruleset
will probably more secure anyhow. :)
-- The International NudeNet
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[ Parent
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IANACLB (Score:4, Interesting)
by hey! (mattleo@treehouse.acrcorp.com) on 2002.02.27 11:21 (#3078804)
(User #33014 Info | http://slashdot.org/)
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IANACLB (I Am Not a Command Line Bigot), but doing better than a CLI
interface in an area like this is a tall order. It's not something you can
just slap onto the product in a few days (as most VPN box configuration GUIs
I've seen appear to be).
The
problem with the GUI interfaces I have seen is that they really don't give
you any effective conceptual support. You have to figure out the topology
and requirements of your network, then you do this bit of intellectual gymnastics
that turns these global requirements and properties into settings for each
individual box, THEN you sit down at your GUI. At that stage, the GUI can
have very little benefit, since you are talking about a half dozen relatively
simple commands you need to type in. In fact, typing them in means you can
keep them in a little word processor file and send them to the box over and
over again with little changes -- good for setting up multiple boxes or for
playing around with a single box you are repeatedly pin-resetting.
To
really help a person like you who doesn't have time to bone up on every box
you are working with, what you really need is something that is kind of a
cross between a network management system and a CAD system. You would sketch
out your network, and drop little dollops of distinctively colored "paint"
on each network or host that needs to participate in some virtual network.
The system would then output configurations to download to each of the participating
firewalls or hosts.
A GUI that just configures and individual box does practically nothing for you.
--
----
It's bad luck to be superstitious.
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[ Parent
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Where to get Freeswan packages for Red Hat (Score:2)
by Nailer on 2002.02.27 15:47 (#3080965)
(User #69468 Info | http://www.cyber.com.au/)
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Unless your distro can with FreeSWAN, you have to recompile your kernel with modifications.
Non-US
distributions like SuSE and Debian can include Freeswan in their list of
apps. US based ones like Red Hat can't. But some lovely fellows at Steambaloon
[steambaloon.com] (a Linux security consulting firm - no, I work for someone
else) produce source and binary packages of the original and updated Red
Hat kernels (with the AC patches, extensive testing, and old 2.4 VM) with
Klips, the kernel level part of ipsec, compiled in.
-- -- If you run Red Hat, and don't know about FreshRPMs and Apt-get [freshrpms.net], find out.
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[ Parent
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How stupid is the CTO? (Score:1)
by SharpNose on 2002.02.27 16:21 (#3081178)
(User #132636 Info)
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Let's see: provided I know FreeSWAN, I can grab a machine and start
setting it up immediately. If I want to get something commercial and very
expensive, I have to fill out how many forms, get approval from how many
people, wait for it to get ordered how long? Exactly where are you starting
your clock when you say "configured from GUI in a few hours?"
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[ Parent
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Re:What's complicated about FreeSWAN? (Score:3, Interesting)
by LWolenczak (lw@lwolenczak.net) on 2002.02.27 9:25 (#3077934)
(User #10527 Info | http://slashdot.org/)
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The FreeS/WAN people don't document everything that you can do with frees/wan.
Its very neat when you get down to the point where your playing with dozens
of tunnels confiugred every which way.
One
of the things that they don't tell you how to do, i guess so they don't get
asked questions, is how to put gre traffic inside of an ipsec tunnel and
make it work right. Also, it seems to have slipped by that you CAN make
two linux 2.4 secure gateways talk to each other over the ipsec tunnel.
I have a couple samples of some of the neat things I have done at http://lwolenczak.net/ipsec.html
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[ Parent
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Re:What's complicated about FreeSWAN? (Score:3, Interesting)
by Etyenne on 2002.02.27 10:40 (#3078498)
(User #4915 Info)
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Complicated thing with FreeSWAN :
- Client behind NAT
- Left/Right side nomenclature really confuse me; they could have used "peers" or client/server, I don't know
-
Recompiling kernel; easy if you have a single box, quite hard when you manage
30+. Plus it require you to commit the sin of rebooting the machine.
At
work, we have choosen CIPE for Linux-Linux VPN. It is totally userland,
come stock on recent RedHat version and is available as RPM; all that make
it is easy to install and upgrade on a lot of machines. Plus the config
file is really dumb-proof. We are stuck using PPTP for Windows-Linux VPN
because that's all the Windows monkeys know about. -- :wq
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[ Parent
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Re:What's complicated about FreeSWAN? (Score:1)
by pivo on 2002.02.27 11:17 (#3078772)
(User #11957 Info)
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From my understanding of FreeSWAN, it's not intended to connect many
machines to a central point, for example a VPN for home manchines connected
to a central office. It's intended to link offices together. So you should
only have to install it on the specific machines that link those offices.
If you're company's so big or disperse that you have thirty officies, then
I guess you would have to recompile each kernel, though you'd be smarter
to have identical machines and build the kernel once then distribute it to
each machine.
We
use PPP over SSH for our home/office VPN for Linux and Solaris. It works
very well and since it was originally a skunworks project, we didn't even
have to get IT to open any new ports since SSH was already supported.
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[ Parent
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Re:What's complicated about FreeSWAN? (Score:2)
by LinuxGeek8 on 2002.02.27 11:57 (#3079084)
(User #184023 Info | http://chaosmongers.org/)
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I am struggling for some time now to get it going, but I still do not understand how it works. On my end I have a linux firewall with iptables. And
what I could not figure out is what to do with the packet filtering, do I
need to accept traffic over 50/ip on the ipsec0 interface or the eth0 interface.
Same question for the 500 udp/ip traffic.
And the other part of the
network is connected to a freebsd server with racoon running. That is a completely
different ipsec implementation. At least for configuring it is different.
I
believe running a packet filter is quite hard if you want to do it right.
You have to understand networking and just play with for a few weeks just
to understand it. If anyone would tell me he has a secure packet filter
running, but cannot explain how it works, I just cannot believe it. You just
have to know what you are doing. Same with ipsec. Ipsec is not only networking, but also crypto. So there is more you need to know about it, and it adds extra complexity to firewalling. --
--
Help me people, this has to stop. I know everything.
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[ Parent
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Re:What's complicated about FreeSWAN? (Score:1)
by pfunkmallone on 2002.02.28 14:44 (#3086925)
(User #89539 Info)
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On your eth0 interface of the firewall, you need to allow 500 udp, and
50 tcp (if you're using ESP which is default). This allows the IPSEC peers
to setup the tunnel. http://www.freeswan.org/freeswan_trees/freeswan-1. 95/doc/firewall.html
According
to the FreeSwan folks, no firewalling NEEDS to be done on the ipsec0 interfaces,
as all packets coming through this tunnel are already being disassembled
and "cleaned-up" by freeswan itself.
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[ Parent
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- 1 reply
beneath your current threshold.
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why? (Score:0)
by tplayford (tom@sail - i t aly.com) on 2002.02.27 8:51 (#3077734)
(User #308405 Info | http://127.0.0.1:808...pmt5FPQQAgE/gibbon/)
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I'm sure this book is very usefull etc. But I've set up serveral internationl
linux based VPN's now and it really isn't that difficult.
I suppose this is the same for almost all computer books, easy if you know how...
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[ Parent
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Re:why? (Score:2, Insightful)
by MonkeyBot on 2002.02.27 9:09 (#3077844)
(User #545313 Info)
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Sometimes, there are special constraints on the networks you are working
with. For instance, I need to use stuff that uses IP, but since PPP over
SSH is strictly TCP, I can't use that option. Moreover, my boss is a paranoid
guy that doesn't trust some 24-year-old punk (me) to run his firewalls, so
both offices have managed firewalls through different ISPs, ruling out the
possibility of a single ISP routing traffic over its network to the other
office so that I don't have to do anything. This adds additional constraints
because since I can't control the firewall without going through pains with
both ISPs for several days, I can't even open a port for something like PPTP
(which I really wouldn't want to do anyway). Granted, I can probably find
out what I need to know from a Google search, but it would be nice to have
all the common VPN solutions covered--even just introduced--in a book format.
I'm buying it.
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Re:why? (Score:2)
by Junta on 2002.02.27 13:10 (#3079648)
(User #36770 Info)
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Of course, ppp over ssh implies a full IP tunnel using ppp with ssh underneath,
IP in TCP encapsulation, essentially. You get full IP functionality this
way, though the architecture is horribly flawed (TCP connections run with
TCP somewhere underneath, very bad when packets get loss and two layers start
doing recovery).
Now
ssh without ppp on top supports only TCP tunnels, I'll assume that is what
you are talking about. A statement that says you need to use IP, but you
only get TCP sounds really goofy, since TCP rides on top of IP, phrasing
it with the protocols you need (i.e. udp, icmp, etc) would have made the
post more sensible (that and omitting ppp...). If I heard someone make the
statement you just made I wouldn't trust them with firewall configuration
either...
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[ Parent
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Re:why? (Score:2)
by Pii (jedi.lightsaber@org) on 2002.02.27 13:31 (#3079810)
(User #1955 Info | http://port80.filtered.by.cox.com/)
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What do you mean, "PPP over SSH is strictly TCP?"
Are you saying that ICMP, or UDP, traffic is unable to utilize this tunnel?
That is certainly not correct. Just as PPP carries all of your IP
traffic (any protocol) between your home and your ISP, a PPP over SSH tunnel
will also carry whatever you need it to. --
- Sig is a trademark of SigArms. [sigarms.com]
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[ Parent
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Re:why? (Score:2)
by Bender Unit 22 (root@localhost) on 2002.02.27 12:13 (#3079206)
(User #216955 Info | http://www.johnschmidt.dk/ | Last Journal: 2002.01.11 11:07)
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It's not when it works you need the books. It's when it doesn't work you'd wish you had the book. I have configured a VPN with the help of a HOW-TO page and it worked. B ut
when you want to do larger setup's in the "real" world. All kinds of questions
comes and demands comes to mind and it's nice to be on top of things and
be able to say from the first meeting, what is possible and what is not. -- --------
Trojans, not just for hiding soldiers anymore!
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VPN hardware (Score:1, Troll)
by pokka on 2002.02.27 9:02 (#3077793)
(User #557695 Info)
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Building VPNs is a pain in the ass, regardless of whether you're using
windows NT/2k or linux. Microsoft's documentation is sketchy (and in some
cases completely wrong), and there are very few sources for building a VPN
in Linux.
This book may make it easier to build a VPN, but it's kind of obsolete, now that the Linksys VPN router
[linksys.com] has been released, making it a matter of plugging in and turning
on. Of course, if you have plenty of free time, but very little money,
you might go for the book instead.
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[ Parent
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Re:VPN hardware (Score:2, Interesting)
by Cyno on 2002.02.27 9:38 (#3078046)
(User #85911 Info)
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...or if you're worried about security. I never trust commercial companies
to deliver secure code. Specially if they keep it closed source. Unless
you want to flash the rom on this thing every few weeks I'd just read up
on a linux ppp over ssh solution and write some scripts to keep that software
updated.
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Re:VPN hardware (Score:1)
by starpool on 2002.02.27 19:12 (#3081956)
(User #562363 Info)
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We started out making slow progress with FreeS/WAN trying to connect
to a Raptor Firewall, and thought we'd try to take the easy way out and use
two Linksys VPN Routers. Bottom line: the LVRs will only allow one Class
C subnet access to the tunnel. Since we have multiple subnets at 4 different
locations, the LVR is disqualified, at least for now. (Maybe Linksys will
add this capability to future firmware.) So we're back to FreeS/WAN and
Raptor...now if I can just get that book at my local BN.
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[ Parent
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| - 1 reply
beneath your current threshold.
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What's wrong with PPTP? (Score:4, Interesting)
by Jacco de Leeuw on 2002.02.27 9:06 (#3077826)
(User #4646 Info | http://www.jacco2.dds.nl/)
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PPTP is often used for 'road warrior' setups, i.e. people working from
home or on the road. It's cheap because there are free (as in speech) PPTP
servers for Linux and the Windows PPTP clients are free too (as in beer).
In contrast, Windows IPSEC clients are often expensive.
So, what's wrong with it then? Well, the security of PPTP apparently depends on the password.
A German student [uni-freiburg.de] has written software which can crack the password in a couple of hours on a Pentium II.
c't (Heise) [heise.de] reported about this. --
Jacco
-------
Slashdot. Neuter that Nerd. Formats Stuff.
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[ Parent
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Re:What's wrong with PPTP? (Score:2, Informative)
by Anonymous Coward on 2002.02.27 9:19 (#3077901)
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It's Point-to-Point Tunneling Protocol and thus more limited than IPSec
which can be used in routed mode and can connect arbitrary networks.
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[ Parent
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Re:What's wrong with PPTP? (Score:3, Interesting)
by FallLine on 2002.02.27 9:25 (#3077939)
(User #12211 Info)
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Well firstly, Microsoft's implimentation of PPTP is insecure, buggy on
the client side (and the server side, where their server is used), and has
a hard time supporting multiple clients in a NAT environment.
Secondly,
a lot of older hardware has little to no support for the GRE protocol that
PPTP depends on. Thus many people simply can't use it.
Thirdly, it's
virtually impossible to get two people connecting to the same VPN behind
the same NAT network on any hardware. The nature of GRE makes it very difficult
since it has no concept of port to diffentiate between packets, only source
and destination IP. Unfortunately, NAT is very common these days so this
really does matter.
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[ Parent
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Re:What's wrong with PPTP? (Score:0, Troll)
by icedivr on 2002.02.27 14:44 (#3080500)
(User #168266 Info)
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If it's so insecure, why aren't people getting cracked all the time?
Secondly,
since when does hardware support a networking protocol in the absense of
software? Any machine that can run 95 or 98 can run PPTP. They have pretty
modest hardware requirements by today's standards.
Thirdly, I have created multiple outbound pptp tunnels behind an ICS connection. It can be done.
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[ Parent
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Re:What's wrong with PPTP? (Score:3, Informative)
by Junta on 2002.02.27 9:40 (#3078066)
(User #36770 Info)
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Just FYI, but Win2k and newer (at least) include native IPSEC support
that can interoperate with FreeS/WAN and such. Other systems, well, they
are intended for home use that doesn't need that functionality..
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[ Parent
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Wrong: Win2K IPSEC uses L2TP for tunneling (Score:1)
by Xenophon Fenderson, (xenophon+slashdot@irtnog.org) on 2002.02.27 11:24 (#3078826)
(User #1469 Info | http://web.irtnog.org/~xenophon/)
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Windows 2000/XP's support for IPSEC is limited to transport mode. Tunnelling
is handled by Cisco's Layer 2 Tunnelling Protocol (L2TP). Unless FreeS/WAN
and KAME now support L2TP, IPSEC VPNs using Windows-native clients are limited
to routable IP addresses all the way around.
Now NAT is evil---ask my friends, I rant about it all the time---but
in the real world, one must be able to tunnel VPN traffic at least in one
direction (into the company). Without support for L2TP in FreeS/WAN or commercial
IPSEC clients in Windows, one cannot currently do this.
Please, I beg you, prove me wrong. I've been struggling to get Windows
IPSEC working with KAME for some time now. And my copy of Cisco's Unity
VPN client doesn't work on XP. -- -- I'm proud of my Northern Tibetian Heritage [subgenius.com]!
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[ Parent
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Re:Wrong: Win2K IPSEC uses L2TP for tunneling (Score:2)
by Junta on 2002.02.27 12:40 (#3079371)
(User #36770 Info)
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L2TPd for linux exists, separate from FreeS/WAN. Though commonly coupled
with IPSEC, L2TP is separate. I have heard reports that FreeS/WAN+l2tpd
can be used to provide the functionality you describe to have a pretty solid
VPN with FreeS/WAN and Windows ends.
http://www.marko.net/l2tp/
A bit dated, but reportedly still functional...
Now as far as getting connectivity to Cisco with Windows with tunneling, I have no idea, never tried...
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[ Parent
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Re:What's wrong with PPTP? (Score:2)
by Junta on 2002.02.27 21:41 (#3082448)
(User #36770 Info)
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http://www.freeswan.org/freeswan_trees/freeswan-1. 95/doc/interop.html contains
some links, right now the tripod exceeded bandwidth, and that is the one
with Windows interop. instructions, but I have seen it and it looks pretty
solid.
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[ Parent
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Re:What's wrong with PPTP? (Score:2, Informative)
by jeremiahstanley (miah@miah . o rg) on 2002.02.27 9:45 (#3078100)
(User #473105 Info | http://www.miah.org/)
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With Win2k you can get this
[microsoft.com] little patch and then you have a free as in beer IPSec implementation
provided by Microsoft under Win2k. It even supports x509 certs. IPSec clients
are not that expensive. Look at SSH Sentinal
[ssh.com] for another option. It even supports the newer AES ciphers (which
I don't expect out of Microsoft for a long time)as added security.
For all of this you have to patch the code [freeswan.org] to use the newer ciphers. You can get that here [irrigacion.gov.ar] and if you need to use x509 certs you can get that stuff here [strongsec.com]. This is all pretty easy if you have you druthers about compiling new kernels and working with OpenSSL.
Why
this isn't in the kernel to begin with is anybody's guess. I would guess
that it has something to do with all those pesky crypto export laws. Just
like everything else in the ol US of A we have to sacrifice our freedoms
so that we can be safe from the KGB and that one guy from Hackers [imdb.com]. --
Every so often, I like to go to the window, look up, and smile for a
satellite picture. -- Stephen Wright
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Its damn slow (Score:1)
by moankey on 2002.02.27 10:08 (#3078275)
(User #142715 Info)
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From testimonies of traveling whatevers the people always complain that
PPTP is very sloooow. They preferred using RAS in place, albeit a very expensive
phone bill.
Most were of course higher level execs so their complaining actually mattered.
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[ Parent
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Re:What's wrong with PPTP? (Score:0)
by Anonymous Coward on 2002.02.27 10:19 (#3078347)
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So,
what's wrong with it then? Well, the security of PPTP apparently depends
on the password. A German student [uni-freiburg.de] has written software
which can crack the password in a couple of hours on a Pentium II.
Thank god I'm not in Germany!!!!
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[ Parent
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Re:What's wrong with PPTP? (Score:0)
by Anonymous Coward on 2002.02.27 10:26 (#3078396)
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You can buy PGPnet (IPsec client) in most office depots , office max,
or Circuit City for $39. It has the same functionality as the NAI version.
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[ Parent
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PGPnet (Score:3, Informative)
by Jacco de Leeuw on 2002.02.27 10:37 (#3078474)
(User #4646 Info | http://www.jacco2.dds.nl/)
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That's because NAI doesn't know what to do with it. Could they be dumping
the product for $39? They want to sell off some parts currently included
with PGPnet. There's some uncertainty if you buy the product. Will they update
it? Will they fix bugs? --
Jacco
-------
Slashdot. Neuter that Nerd. Formats Stuff.
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[ Parent
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wireless PPTP == readable password file (Score:1)
by nealmcb on 2002.03.01 9:59 (#3091216)
(User #125634 Info | http://bcn.boulder.co.us/~neal/)
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The Heise article is in German, but refers to
the original paper which is
in English [uni-freiburg.de]
Normally, the file /etc/shadow (or /etc/password on old systems)
is regarded one of the most vulnerable points of an unix system [Uni99].
If an attacker can obtain the information in this file, the system is nearly
hacked. Using Microsoft's PPTP protocol, information about your passwords
is not only publicly available, you also provide additional hints about the
passwords, which allow to speed-up the attack by a factor of up to 2^16 .
With this said, it is clear why we believe Microsoft's PPTP implementation isn't suitable for securing wireless networks.
--
--Neal
Go IETF [ietf.org]!
Go CPSR [cpsr.org]!
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[ Parent
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Problem is getting Management to go along (Score:2, Interesting)
by Cy Guy on 2002.02.27 9:27 (#3077946)
(User #56083 Info | http://www.digitalri...04_affiliatesLP.html | Last Journal: 2002.05.20 18:38)
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I think the priority should be getting management to understand the importance
of using standard protocols instead of proprietary ones.
Having a book like this one
[amazon.com] is great if you want to familiarize yourself with the standards
and how to implement them on Linux, but the much harder task is getting Management,
particularly at larger companies, to see the benefit of implementing a standards
based VPN where the users can use any standards based client over any TCP/IP
network.
Instead what I see is managers that want to buy a single
product that comes with both the server and client applications, but then
doesn't work or is hard to implement when the clients are trying to access
the VPN from a cablemodem, DSL, or 802.11 connected machine, and don't (God
forbid) want to use MSIE and Citrix on Windows to get onto the office network.
-- We ought to care less about rules & regulations [amazon.com]
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[ Parent
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Re:Problem is getting Management to go along (Score:0)
by MojoReisen (jgrabowski.abm@com) on 2002.02.27 22:00 (#3082501)
(User #218327 Info)
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You've got that right.
We're
tasked with supporting Citrix IE-ALE Windows VPN clients with FlowPoint modems
or Instant Internet boxes over DSL. Of course it is completely unrealiable. The
task is truly Herculean. They (vendors)all point their fingers at each other,
and I'm waist-deep in IPSec, MTU's ,etc. and all that other black magic.
-- --Inter caecos regnat luscus.
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[ Parent
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Can't beat SSH (Score:2, Insightful)
by schlach on 2002.02.27 9:27 (#3077953)
(User #228441 Info)
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for simple encrypted forwarding
LocalForward 8080 theproxy:8080 LocalForward 25 thesmtp:25 LocalForward 143 theimap:143
Don't forget your '-g' =)
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[ Parent
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SSH != VPN. That's a good thing. (Score:1)
by Bri Hatch on 2002.02.27 11:32 (#3078902)
(User #523490 Info | http://www.ifokr.org/bri/)
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We have a section about when a VPN is not what you need, and these are the exact kind of examples when a VPN is unnecessary overkill.
As a side note, if you use '-g', make sure you have iptables/ipchains/hosts.{allow|deny}
rulesets enabled to make sure that only authorized machines can use the gateway.
Otherwise anyone in the world can use your encrypted tunnel.
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[ Parent
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Re:SSH != VPN. That's a good thing. (Score:2)
by brassrat77 (brassrat77 AT yahoo DOT com) on 2002.02.27 14:33 (#3080403)
(User #9533 Info)
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As a side note, if you use '-g', make sure you have iptables/ipchains/hosts.{allow|deny}
rulesets enabled to make sure that only authorized machines can use the gateway.
This is an EXCELLENT POINT that CANNOT BE OVEREMPHASIZED.
I recently had to set up tunnels to allow a set of NAT'd workstations
(laptops runnin a mix of Linux and W2K) access a system on the inside of
a remote firewall where SSH was the only available securable protocol. We
needed to use the "-g" switch, and the need for filtering access was immediately
apparent. We ended up using a set of scripts to build the tunnel, including the necessary iptables rules.
As an aside, I'd check if hosts.allow|deny rules are sufficient -
I think the ssh tunnel would make all connections appear to be coming from
the host running the tunnel. (Can't check for myself right now)
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[ Parent
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The main problem with IPSEC... (Score:5, Insightful)
by Junta on 2002.02.27 9:48 (#3078126)
(User #36770 Info)
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IPSEC is wonderful, but many businesses don't think things through and
use it for telecommuting. Why is this bad? Well, the way this works is
that someone connects to the VPN system and gets a full tunnel that allows
the authorized client to behave on the internal network as if it was actually
there, bypassing the firewall. The problem here is pretty obvious. The
client machine is not protected by a firewall,a nd so if the client is compromised,
an attacker has a clear path straight past the firewall. So the effectiveness
of the firewall is greatly reduced.
Now
if you don't have a firewall protectecting the network, this won't hurt,
but if you do, then a solution like ssh is somewhat more secure, as you only
set up the tunnels you absolutely need to very specific hosts. While there
is still a risk, it is greatly reduced and strikes a good balance between
usability and security.
What IPSEC *is* good for is seamlessly connecting
sites together without really expensive dedicated lines securely. While
it makes no guarantee as to bandwidht or availability, it does provide almost
the same level of security. If a company can't afford lines to sites but
still wants to expand, IPSEC is ideal. I use it to connect my home private
network to a friends home private network. The key here is that not only
do you have to trust the clients whose keys you permit to connect, but you
must also trust that the administrator of that client machine or network
is sufficiently competent to keep his network secure, as the security of
the two networks is tied a lot more closely together...
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[ Parent
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Re:The main problem with IPSEC... (Score:1, Informative)
by Anonymous Coward on 2002.02.27 9:58 (#3078205)
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Actually, this is bypassed by disabling split tunneling (allowing the
client machine to access the internet "directly" and accessing the VPN tunnel).
-m
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[ Parent
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Re:The main problem with IPSEC... (Score:2)
by j7953 on 2002.02.27 12:19 (#3079240)
(User #457666 Info)
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Actually,
this is bypassed by disabling split tunneling (allowing the client machine
to access the internet "directly" and accessing the VPN tunnel).
Well, but that doesn't prevent the telecommuter's computer to become compromised
with some background logging software that'll collect information when connected
to the company network, and send it to the attacker when connected to the
internet.
Of course, using an SSH tunnel also doesn't solve that problem.
The only real option is to assign IPs from a different subnet to the telecummters'
home computers, and having a firewall between that subnet and the rest of
the company network that'll not allow access to certain ressources that are
especially critical. And, of course, the telecommuters must be educated
about the security issues. -- Sig (appended to the end of comments I post, 54 chars)
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[ Parent
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Re:The main problem with IPSEC... (Score:2, Informative)
by icedivr on 2002.02.27 10:10 (#3078285)
(User #168266 Info)
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Your beef can be easily solved by ensuring that the remote machine's default route is down the tunnel.
As
far as I'm concerned, a bigger threat is the road warrior laptop not having
adequate virus protection. (VP of Sales does insist on Windows, doesn't
he?) Desktops behind the firewall presumably have multiple layers of protection
in front of them, the road warrior, maybe not.
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[ Parent
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Re:The main problem with IPSEC... (Score:2)
by Shoten on 2002.02.27 10:29 (#3078417)
(User #260439 Info)
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So, you're saying the main problem with IPSEC is that it's not a magic
bullet? Nothing is...get over it. I've heard people say the same about
firewalls, saying how firewalls make people think that they're totally secure,
so they no longer patch systems or pay attention. That may be true sometimes,
but it's still not a valid argument that firewalls are flawed. Security
isn't one box or one piece of software, and saying that one has a problem
because it doesn't blanket everything is like criticizing deadbolts because
thieves can still break a window to get into your home.
--
A fool and his money are soon venture capital.
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[ Parent
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Re:The main problem with IPSEC... (Score:2)
by Junta on 2002.02.27 11:53 (#3079060)
(User #36770 Info)
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Right, but I was saying that IPSEC is not only not a magic bullet (that
is to be expected) but companies outright misuse the technology without any
serious thought. They invest tons in making sure they have tight firewalls
and policies that prohibit people from hooking up modems to the outside world
(internet without firewall), and yet repeat the mistake in a different form
time and time again. It would be nice to establish trusted connections to
telecommuters, but it just simply can never be secure enough (well, maybe
if the telecommuter is the same person who designed the corporate security
and takes home security equally seriously, but not worth finding out).
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[ Parent
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Re:The main problem with IPSEC... (Score:2)
by Shoten on 2002.02.28 8:15 (#3084102)
(User #260439 Info)
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I see your point, but at that stage of the game, it's not the technology
that is to blame. Any solid technology will be a problem if it is not part
of a sound, well-thought out implementation. There are ways around the problem
as well, however; for example, Checkpoint VPNs can push a security policy
out to the client upon connection, enforcing a firewall policy at the end
point and prohibiting network communications between that point and any node
besides the VPN gateway. But that's a whole other ball of wax, and returns
to the issue of making wise choices when rolling out technology. The
bottom line is, VPNs make it possible to do things in business that aren't
cost-effective any other way, and businesses are there to make money, not
to be secure. It's a trade-off, and if the return outweighs the risk, it's
worth the risk.
--
A fool and his money are soon venture capital.
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[ Parent
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Re:The main problem with IPSEC... (Score:1)
by Sloppy on 2002.02.27 10:59 (#3078631)
(User #14984 Info | http://slashdot.org/ | Last Journal: 2002.07.17 10:59)
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So the effectiveness of the firewall is greatly reduced
Don't you have the same exact problem with desktop machines on the LAN,
inside the firewall? Seems to me that VPN-though-a-firewall doesn't introduce
any vulnerabilities that you don't already have. -- "Oh no, 3 horny women and only 2 condoms...Thank god I read slashdot" -- Anonymous Coward
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[ Parent
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Re:The main problem with IPSEC... (Score:0)
by Anonymous Coward on 2002.02.27 11:38 (#3078946)
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But LAN machines have never been exposed to the internet. I am sure somebody
can put some "fun" deamons up on a machine just waiting for a VPN connection.
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[ Parent
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Re:The main problem with IPSEC... (Score:1)
by Sloppy on 2002.02.27 12:18 (#3079239)
(User #14984 Info | http://slashdot.org/ | Last Journal: 2002.07.17 10:59)
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But LAN machines have never been exposed to the internet.
Ha hah hah ha! That's a good one.
Seriously, it must be nice to work at a place where they haven't heard
of "Active Content" and no one uses products like Microsoft Word or Microsoft
Outlook. :-) -- "Oh no, 3 horny women and only 2 condoms...Thank god I read slashdot" -- Anonymous Coward
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[ Parent
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Re:The main problem with IPSEC... (Score:2)
by Junta on 2002.02.27 12:48 (#3079450)
(User #36770 Info)
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When dealing with internal systems, you can enforce all kinds of policies
about virus software, etc. You can keep it relatively boxed. With telecommuting,
the clients not only have relaxed restrictions, but also are vulnerable while
connected to the internet to the sort of attacks firewalls are meant to keep
out. Normally, this wouldn't be too bad, but with a full tunnel, that machine
will probably contain sensitive information itself and, for the duration
of the connection, gives full access to a corporate network if compromised.
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[ Parent
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Re:The main problem with IPSEC... (Score:0)
by Anonymous Coward on 2002.02.27 14:07 (#3080140)
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If you want to get legalistic about it:
Local
Area Network by definition is not a Wide Area Network now is it? If you have
a LAN you cannot be exposed to the internet or it is a WAN. If you run active
content then you are running code on the LAN. Don't run unknown code on a
LAN. If you downloading something from the internet you are using a WAN interface
are you not?
The point is you have a machine that has been directly
exposed to the intenet and now it is on your network and that is NOT the
same thing.If I have to go to the head at a bus station I will finish my
drink because I won't really know what it is when I get back.
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[ Parent
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Re:The main problem with IPSEC... (Score:1)
by -audiowhore- on 2002.02.27 16:08 (#3081115)
(User #153163 Info)
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Bollocks! There are quite a few commercial VPN clients out there that
either have a 'stateful' firewall engine (Check Points Secure Client), and
some others that support personal firewall software (the Cisco client has
support for Black Ice and Zone Alarms). The Cisco client can be configured
to not install or initialise *unless* the personal firewall is installed/running.
--audiowhore
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[ Parent
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Re:The main problem with IPSEC... (Score:2)
by Junta on 2002.02.27 21:22 (#3082392)
(User #36770 Info)
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But then, how do you ensure the client is using approved software if
you are using a standard like IPSEC? I know, corporate policy, but if people
are at home, they might try more exotic things... In any event, clients
configured like this are a good way to make IPSEC *better* for telecommuting,
but the safest bet is to not have full network transparency, but instead
only have selected services that telecommuters need and allow only those
in your preferred method of access..
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[ Parent
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CIPE - a better solution. (Score:3, Informative)
by ion++ on 2002.02.27 10:18 (#3078339)
(User #134665 Info | http://www.pony.dk/)
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I'm using CIPE for linux at work. It can be found at http://sites.inka.de/sites/bigred/devel/cipe.html [sites.inka.de] or for windows at http://cipe-win32.sourceforge.net/ [sourceforge.net].
It's a better solution
[sites.inka.de] because it doesnt run TCP over TCP, which can give a problem,
when retransmission occurs. With the right ammount of bad luck, you can have
double retransmission where both layers of TCP retransmit. CIPE runs completely
over UDP to avoid this problem.
JonB -- Some AC: The Drunken System Administrator. "You lost your password huh? That sucks. Keep guessing!"
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[ Parent
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Re:CIPE - a better solution. (Score:2, Insightful)
by ion++ on 2002.02.27 10:22 (#3078367)
(User #134665 Info | http://www.pony.dk/)
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Oh yeah, i forgot to mention that it works behind a NAT, which IPSEC has trouble with. Further
more it works with non-static ip address. Obviously one end needs to know
the ip of the other end, but thats all which is needed.
JonB -- Some AC: The Drunken System Administrator. "You lost your password huh? That sucks. Keep guessing!"
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[ Parent
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Re:CIPE - a better solution. (Score:1)
by The Darkness on 2002.02.27 11:29 (#3078878)
(User #33231 Info | http://slashdot.org/)
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Oh yeah, i forgot to mention that it works behind a NAT, which IPSEC has trouble with.
Junta already posted a valid response to this statement.
Further more it works with non-static ip address. Obviously one end needs
to know the ip of the other end, but thats all which is needed.
FreeS/WAN works great with non-static IP addresses.
For example:
/etc/ipsec.conf
conn netnet
left=theirhost.dyn.dhs.org
leftid=@theirhost.dyn.dhs.org
leftsubnet=10.1.1.0/24
right=%defaultroute
rightid=@myhost.dyn.dhs.org
rightsubnet=10.1.2.0/24
leftrsasigkey=....
rightrsasigkey=....
authby=rsasig
auto=start
And in ipsec.secrets:
@myhost.dyn.dhs.org : RSA {
...
}
I have been using a similar configuration since the release of FreeS/WAN v1.5. -- --
Signature
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[ Parent
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Re:CIPE - a better solution. (Score:2, Informative)
by Junta on 2002.02.27 10:39 (#3078494)
(User #36770 Info)
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Better solution than, say, ppp over ssh (a really dumb hack), but not better than IPSEC for most all applications.
IPSEC
also does not run TCP over TCP, it uses udp for isakmp, and data is transmitted
through custom protocols (numbers 50 and/or 51), *not* through TCP.
Another
thing about IPSEC that works better than CIPE is that IPSEC more strongly
authenticates the machine at the other end. This is why NAT breaks, because
unlike CIPE, IPSEC works to ensure the packet has passed unmodified since
leaving a known trusted host, and the very nature of NAT prevents this.
Solution is simple, move the IPSEC gateway to either the NAT system or beyond.
Though it is being pushed in many circles as a good solution for telecommuting,
it really was never designed for that and that usage really spits in the
face of firewalls.
Finally, CIPE lacks compatibility. Sure you can
configure windows and linux boxes and maybe other platforms, but just try
to connect to, say a CISCO router....
CIPE is a hack that creates
more problems than it solves in the long run. PPP over ssh is worse, but
a dumb idea, set up tunnels for specific tcp services that you need, more
overhead, but security is better (not perfect, but better). For connecting
networks together, a good architect can piece together an IPSEC solution
that guarantees identity at other end of the pipe... CIPE offers the gaping
whole that IPSEC can while not offering enough identification. So ssh or
IPSEC remains the best solution, depending on the problem.
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[ Parent
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Answer? (Score:3, Funny)
by sharkey on 2002.02.27 10:29 (#3078412)
(User #16670 Info)
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Why does every book need to include the magic 'L' word in the title nowadays?
Because they have a better chance of getting posted to the Slashdot homepage? --
--
"Outlook not so good." That magic 8-ball knows everything! I'll ask about Exchange Server next.
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[ Parent
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Crossplatform aspect? (Score:2, Interesting)
by egghat on 2002.02.27 10:51 (#3078571)
(User #73643 Info)
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How is the crossplatform aspect covered? There are hundreds of possible
solutions for VPNs out there, but if you want something that works on *nix,
Windows and Mac (Classic and X) and is free and open, the range of products
to choose from gets small ...
For example, I couldn't find a free IPSEC client for Windows.
Any new hints from this book?
Thanks in advance.
egghat. -- --
"As a human being I claim the right to be widely incosistent", John Peel
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[ Parent
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Re:Crossplatform aspect? (Score:3, Informative)
by Junta on 2002.02.27 10:53 (#3078587)
(User #36770 Info)
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IPSEC "clients" for Windows: PGPnet- commercial and free versions. Free version doesn't do complicated routing stuff Windows 2000 and newer have built in IPSEC capabilities.
Both these methods can interact with CISCO, OpenBSD, and FreeS/WAN.
IPSEC is the best shot you have at a cross-platform standard.
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[ Parent
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Re:Crossplatform aspect? (Score:1)
by Bri Hatch on 2002.02.27 11:28 (#3078871)
(User #523490 Info | http://www.ifokr.org/bri/)
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Most of the VPN topics we cover translate easily and directly to other
Unix systems. Some small difference are OS specific. You don't enable ip
forwarding with /proc on solaris, for example, but the software configuration,
routing examples, etc, are the same.
We
discuss PPTP s.t. you can communicate with PPTP-only Windows clients. You
can run IPSec software on more recent versions of Windows, however describing
how to do so would probably increase the size of the book by several hundred
pages, not counting the fact that we'd have lost some serious sanity in the
process.
So when cross platform == unix-like systems, this book does it for you. When cross platform == non unix, you're on your own.
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Semi-OT: any ISPs that route a VPN connection? (Score:1)
by Sloppy on 2002.02.27 11:06 (#3078670)
(User #14984 Info | http://slashdot.org/ | Last Journal: 2002.07.17 10:59)
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Anyone
know of any ISPs (preferably outside USA) that will route stuff coming from
a VPN (or any other type of encrypted tunnel) to The Internet? (i.e. from
The Internet's point of view, it would be like I was a local user of that
ISP, even though I'm physically somewhere else.) Doesn't have to be free
beer. -- "Oh no, 3 horny women and only 2 condoms...Thank god I read slashdot" -- Anonymous Coward
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Re:Semi-OT: any ISPs that route a VPN connection? (Score:2)
by disappear (jon@lasser.org) on 2002.02.27 14:42 (#3080488)
(User #21915 Info | http://www.tux.org/~lasser/)
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Anyone
know of any ISPs (preferably outside USA) that will route stuff coming from
a VPN (or any other type of encrypted tunnel) to The Internet? (i.e. from
The Internet's point of view, it would be like I was a local user of that
ISP, even though I'm physically somewhere else.)
Why would you want to do that? Not only will it slow down your network
connection, but I suspect that it should be fairly easy to do traffic analysis
to determine which traffic was yours in the first place, even at a busy ISP...
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Has anybody used isakmpd on Linux (Score:2)
by Chang on 2002.02.27 11:06 (#3078673)
(User #2714 Info)
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Anybody out there have any success compiling and using OpenBSD's isakmpd on Linux?
I really need to use aggressive mode but the patches for freeswan are ancient/unmaintained.
A pointer would be greatly appreciated.
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ssh + ppp = vpn (Score:1)
by hopeless case (christopherlmarshall@nospam.yahoo.com) on 2002.02.27 11:11 (#3078722)
(User #49791 Info | http://www.hopelesscase.com)
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Here's this script I use to setup a quick and dirty VPN between my workstation
at work and my home PC. It has to originate from work to get through the
firewall but once setup, of course, packets can flow both ways. I call the
script ssh-vpn.
You
have to setup ssh correctly with rsa keys before it will work. You also
have to download pty-redir. See the VPN mini how-to for more details.
#!/bin/bash
REMOTE_HOST=$1 REMOTE_IP=$2 LOCAL_IP=$3
if [ -z "$1" ] || [ -z "$2" ] || [ -z "$3" ] ; then
echo "usage ssh-vpn "
exit 1 fi
# this file holds the slave pty that the local pppd needs tmpfile=/tmp/tmp$$
# start remote pppd /usr/local/bin/pty-redir
/usr/bin/ssh -1 -o 'Batchmode yes' -t -l root $REMOTE_HOST /usr/sbin/pppd
local ${REMOTE_IP}:${LOCAL_IP} 2> $tmpfile
# give the remote pppd process a little time to send its first connect request sleep 5
#start local pppd /usr/sbin/pppd $(cat $tmpfile) passive
# remove file that held the slave pty file name sleep 5 rm $tmpfile
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The pty-redir hack is dead. (Score:1)
by Bri Hatch on 2002.02.27 11:20 (#3078799)
(User #523490 Info | http://www.ifokr.org/bri/)
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No offense, but anyone still relying on pty-redir should really use a
more recent version of pppd which has the '-p' option to create a pty on
it's own.
The
ppp over (ssh/ssl) stuff in the book is much more complete, allowing you
to make more than one connection, doesn't rely on best-guess 'sleep X' timeouts,
and walks you through setting up ssh securely s.t. it can only be used to
create the VPN, and doesn't require logging in as root from either endpoint.
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Re:The pty-redir hack is dead. (Score:1)
by hopeless case (christopherlmarshall@nospam.yahoo.com) on 2002.02.27 13:08 (#3079628)
(User #49791 Info | http://www.hopelesscase.com)
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Thanks for the info on "-p". I didn't know about that.
You
are correct, of course, about the flaws of my scheme, but you'd be amazed
how well it works for my purposes. I work from home and need to get access
to my work machines through the firewall.
USing my 128k DSL connection to the net, I can do a lot this way, including using VNC acceptably.
I wouldn't recommend it for any production environment, but for simple things it more than fits the bill.
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Re:ssh + ppp = vpn (Score:4, Informative)
by Junta on 2002.02.27 12:14 (#3079217)
(User #36770 Info)
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Of course, ppp over ssh is a bad thing, ugly and bad. For most traffic, you have this topography: TCP over IP over ppp over ssh over TCP over IP, etc...
Note
the fact that we have TCP over TCP, which is bad, very very bad. If a packet
gets lost, we have two layers doing the same thing to restore a connection
and things can get stalled out quickly....
ssh's built in tcp tunneling
suffices for most remote access applications. For a true VPN, IPSEC is the
only good way to go. Other things like CIPE certainly work better than ppp
aver ssh, but still lack in certain features things that IPSEC does. Then
again, if you have to build a VPN where you need to modify packets in transit
(i.e. NAT), CIPE is a viable alternative if you don't mind that packets could
be mangled by more than just the NAT gateways and CIPE wouldn't care, but
I personally want to ensure the highest security with IPSEC...
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Re:ssh + ppp = vpn (Score:1)
by hopeless case (christopherlmarshall@nospam.yahoo.com) on 2002.02.27 13:10 (#3079657)
(User #49791 Info | http://www.hopelesscase.com)
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Yes, it leads to poor performance and an unstable link. Still, for my
purposes (connecting from home to my work machines through a firewall over
a DSL line at 128kbps), you'd be suprised how useful it is.
IPSec
would be better but I would have a lot to learn and experiment with before
I could use it. The ssh+ppp solution is much easier.
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Right in time. (Score:2)
by Bender Unit 22 (root@localhost) on 2002.02.27 12:06 (#3079151)
(User #216955 Info | http://www.johnschmidt.dk/ | Last Journal: 2002.01.11 11:07)
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I have just been playing with IPSec for the last couple of days and wanted
to buy a book on the subject. While I managed to sucessfully make a VPN connection
between 2 machine, I still need to read a great deal about what's under the
hood. So
I looked at amazon also thinking that I could not go wrong with a book from
O'Reilly, but after looking at the few stars it got I had been looking at
this book and the one from RSA. Well, that does it. I'm getting this one.
:)
-- --------
Trojans, not just for hiding soldiers anymore!
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Books cost $$$. (Score:1)
by Vindicated on 2002.02.27 12:25 (#3079274)
(User #562257 Info)
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Of which I have none.
Are there any good web/''net resources for setting up a VPN under Linux? How about VPNs from Linux to Windows and vice versa?
HOWTOs? Tutorials? Utilities like Apachetoolbox, but for VPNs?
Thanks.
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vtun (Score:1)
by joey2k ((moc.retnecwi) (ta) (leoj)) on 2002.02.27 15:13 (#3080725)
(User #472054 Info)
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I tried a few different methods of establishing a vpn between my apartment
and my parents house (also home office). i used cipe for a while but after
getting vtun working, it was a lot better.
i
especially like the compression! i could copy a zip file from my computer
to the server at the other end and the transfer rate was consistent with
the bandwidth cap of my cable modem. but transferring something like an
access database was a lot faster (access dbs can usually be compressed quite
a bit). basically no point to zipping before transfer as it happens automatically.
vtun has quite a few options and methods of transport and i'd highly recommend it!
-- Joel
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Why FATBRAIN? (Score:1)
by ghotiboy on 2002.02.28 9:03 (#3084488)
(User #7771 Info | http://127.0.0.1/)
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Why not use Bookpool? http://www.bookpool.com/.x/hhowgiv3a6/sm/157870266 6
They
are always cheaper for the techy books. I wish they would give me a cut
for all the times I have sent people there. Now they will get /.'ed too.
:-)
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beneath your current threshold. |
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Be careful! UGLY strikes 9 out of 10!
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