From aa0f5b38aec14428b4b80e06f90ff781f8bca5f1 Mon Sep 17 00:00:00 2001 From: Rene Mayrhofer Date: Mon, 22 May 2006 05:12:18 +0000 Subject: Import initial strongswan 2.7.0 version into SVN. --- doc/testing.html | 332 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 332 insertions(+) create mode 100644 doc/testing.html (limited to 'doc/testing.html') diff --git a/doc/testing.html b/doc/testing.html new file mode 100644 index 000000000..77626ba5d --- /dev/null +++ b/doc/testing.html @@ -0,0 +1,332 @@ + + + +Introduction to FreeS/WAN + + + + +Contents +Previous +Next +

Testing FreeS/WAN

+ This document discusses testing FreeS/WAN. +

Not all types of testing are described here. Other parts of the + documentation describe some tests:

installation document: testing for a successful install
configuration document: basic tests for a working configuration
web links document: General information on tests for interoperability between various + IPsec implementations. This includes links to several test sites.
interoperation document.: More specific information on FreeS/WAN interoperation with other + implementations.
performance document: performance measurements

The test setups and procedures described here can also be used in + other testing, but this document focuses on testing the IPsec + functionality of FreeS/WAN.

Testing opportunistic connections

This section teaches you how to test your opportunistically encrypted + (OE) connections. To set up OE, please see the easy instructions in our quickstart guide.

Basic OE Test

This test is for basic OE functionality. + + For additional tests, keep + reading.

Be sure IPsec is running. You can see whether it is with:

    ipsec setup status

If need be, you can restart it with:

    service ipsec restart

Load a FreeS/WAN test website from the host on which you're running + FreeS/WAN. Note: the feds may be watching these sites. Type one of:

   links oetest.freeswan.org

   links oetest.freeswan.nl

+ + +

A positive result looks like this:

+   You  seem  to  be  connecting  from:  192.0.2.11 which DNS says is:
+   gateway.example.com
+     _________________________________________________________________
+                                                                                
+   Status E-route
+   OE    enabled    16    192.139.46.73/32    ->    192.0.2.11/32   =>
+   tun0x2097@192.0.2.11
+   OE    enabled    176    192.139.46.77/32    ->   192.0.2.11/32   =>
+   tun0x208a@192.0.2.11
+

If you see this, congratulations! Your OE box will now encrypt its + own traffic whenever it can. If you have difficulty, see our + OE troubleshooting tips.

OE Gateway Test

If you've set up FreeS/WAN to protect a subnet behind your gateway, + you'll need to run another simple test, which can be done from a + machine running any OS. That's right, your Windows box can be protected + by opportunistic encryption without any FreeS/WAN install or + configuration on that box. From each protected subnet node +, load the FreeS/WAN website with:

   links oetest.freeswan.org

   links oetest.freeswan.nl

A positive result looks like this:

+   You  seem  to  be  connecting  from:  192.0.2.98 which DNS says is:
+   box98.example.com
+     _________________________________________________________________
+                                                                                
+   Status E-route
+   OE    enabled    16    192.139.46.73/32    ->    192.0.2.98/32   =>
+   tun0x134ed@192.0.2.11
+   OE    enabled    176    192.139.46.77/32    ->   192.0.2.11/32   =>
+   tun0x134d2@192.0.2.11
+

If you see this, congratulations! Your OE gateway will now encrypt + traffic for this subnet node whenever it can. If you have difficulty, + see our OE troubleshooting tips +.

Additional OE tests

When testing OE, you will often find it useful to execute this + command on the FreeS/WAN host:

   ipsec eroute

If you have established a connection (either for or for a subnet + node) you will see a result like:

    192.0.2.11/32   -> 192.139.46.73/32  => tun0x149f@192.139.46.38
+

Key:

+ + + + + +

1.	192.0.2.11/32	Local start point of the + protected traffic.
2.	192.0.2.194/32	Remote end point of the + protected traffic.
3.	192.0.48.38	Remote FreeS/WAN node (gateway or + host). May be the same as (2).
4.	[not shown]	Local FreeS/WAN node (gateway or + host), where you've produced the output. May be the same as (1).

For extra assurance, you may wish to use a packet sniffer such as + tcpdump to verify that packets are being encrypted. You should see + output that indicates ESP encrypted data, for example:

    02:17:47.353750 PPPoE  [ses 0x1e12] IP 154: xy.example.com > oetest.freeswan.org: ESP(spi=0x87150d16,seq=0x55)

Testing with User Mode Linux

User Mode Linux + allows you to run Linux as a user process on another Linux machine.

As of 1.92, the distribution has a new directory named testing. It + contains a collection of test scripts and sample configurations. Using + these, you can bring up several copies of Linux in user mode and have + them build tunnels to each other. This lets you do some testing of a + FreeS/WAN configuration on a single machine.

You need a moderately well-endowed machine for this to work well. + Each UML wants about 16 megs of memory by default, which is plenty for + FreeS/WAN usage. Typical regression testing only occasionally uses as + many as 4 UMLs. If one is doing nothing else with the machine (in + particular, not running X on it), then 128 megs and a 500MHz CPU are + fine.

+ Documentation on these scripts is here. + There is also documentation on automated testing + here. +

Configuration for a testbed network

A common test setup is to put a machine with dual Ethernet cards in + between two gateways under test. You need at least five machines; two + gateways, two clients and a testing machine in the middle.

The central machine both routes packets and provides a place to run + diagnostic software for checking IPsec packets. See next section for + discussion of using tcpdump(8) for + this.

This makes things more complicated than if you just connected the two + gateway machines directly to each other, but it also makes your test + setup much more like the environment you actually use IPsec in. Those + environments nearly always involve routing, and quite a few apparent + IPsec failures turn out to be problems with routing or with firewalls + dropping packets. This approach lets you deal with those problems on + your test setup.

What you end up with looks like:

Testbed network

      subnet a.b.c.0/24
+             |
+      eth1 = a.b.c.1
+         gate1
+      eth0 = 192.168.p.1
+             |
+             |
+      eth0 = 192.168.p.2
+         route/monitor box
+      eth1 = 192.168.q.2
+             |
+             |
+      eth0 = 192.168.q.1
+         gate2
+      eth1 = x.y.z.1
+              |
+       subnet x.y.z.0/24

Where p and q are any convenient values that do not interfere with other
+routes you may have. The ipsec.conf(5) file then has, among other things:

conn abc-xyz
+      left=192.168.p.1
+      leftnexthop=192.168.p.2
+      right=192.168.q.1
+      rightnexthop=192.168.q.2

Once that works, you can remove the "route/monitor box", and connect + the two gateways to the Internet. The only parameters in ipsec.conf(5) + that need to change are the four shown above. You replace them with + values appropriate for your Internet connection, and change the eth0 IP + addresses and the default routes on both gateways.

Note that nothing on either subnet needs to change. This lets you + test most of your IPsec setup before connecting to the insecure + Internet.

Using packet sniffers in testing

A number of tools are available for looking at packets. We will + discuss using tcpdump(8), a + common Linux tool included in most distributions. Alternatives + offerring more-or-less the same functionality include:

Ethereal: Several people on our mailing list report a preference for this over + tcpdump.
windump: a Windows version of tcpdump(8), possibly handy if you have Windows + boxes in your network
+Sniffit: A linux sniffer that we don't know much about. If you use it, please + comment on our mailing list.

See also this + index of packet sniffers.

tcpdump(8) may misbehave if run on the gateways themselves. It is + designed to look into a normal IP stack and may become confused if you + ask it to display data from a stack which has IPsec in play.

At one point, the problem was quite severe. Recent versions of + tcpdump, however, understand IPsec well enough to be usable on a + gateway. You can get the latest version from + tcpdump.org.

Even with a recent tcpdump, some care is required. Here is part of a + post from Henry on the topic:

> a) data from sunset to sunrise or the other way is not being
+> encrypted (I am using tcpdump (ver. 3.4) -x/ping -p to check
+> packages) 
+
+What *interface* is tcpdump being applied to?  Use the -i option to
+control this.  It matters!  If tcpdump is looking at the ipsecN
+interfaces, e.g. ipsec0, then it is seeing the packets before they are
+encrypted or after they are decrypted, so of course they don't look
+encrypted.  You want to have tcpdump looking at the actual hardware
+interfaces, e.g. eth0. 
+
+Actually, the only way to be *sure* what you are sending on the wire is to
+have a separate machine eavesdropping on the traffic.  Nothing you can do
+on the machines actually running IPsec is 100% guaranteed reliable in this
+area (although tcpdump is a lot better now than it used to be).

The most certain way to examine IPsec packets is to look at them on + the wire. For security, you need to be certain, so we recommend doing + that. To do so, you need a separate sniffer machine located + between the two gateways. This machine can be routing IPsec + packets, but it must not be an IPsec gateway. Network configuration for + such testing is discussed above.

Here's another mailing list message with advice on using tcpdump(8):

Subject: RE: [Users] Encrypted???
+   Date: Thu, 29 Nov 2001
+   From: "Joe Patterson" <jpatterson@asgardgroup.com>
+
+tcpdump -nl -i $EXT-IF proto 50
+
+-nl tells it not to buffer output or resolve names (if you don't do that it
+may confuse you by not outputing anything for a while), -i $EXT-IF (replace
+with your external interface) tells it what interface to listen on, and
+proto 50 is ESP.  Use "proto 51" if for some odd reason you're using AH, and
+"udp port 500" if you want to see the isakmp key exchange/tunnel setup
+packets.
+
+You can also run `tcpdump -nl -i ipsec0` to see what traffic is on that
+virtual interface.  Anything you see there *should* be either encrypted or
+dropped (unless you've turned on some strange options in your ipsec.conf
+file)
+
+Another very handy thing is ethereal (http://www.ethereal.com/) which runs
+on just about anything, has a nice gui interface (or a nice text-based
+interface), and does a great job of protocol  breakdown.  For ESP and AH
+it'll basically just tell you that there's a packet of that protocol, and
+what the spi is, but for isakmp it'll actually show you a lot of the tunnel
+setup information (until it gets to the point in the protocol where isakmp
+is encrypted....)

Verifying encryption

The question of how to verify that messages are actually encrypted + has been extensively discussed on the mailing list. See this + thread.

If you just want to verify that packets are encrypted, look at them + with a packet sniffer (see previous section +) located between the gateways. The packets should, except for some of + the header information, be utterly unintelligible. The output + of good encryption looks exactly like random noise.

A packet sniffer can only tell you that the data you looked at was + encrypted. If you have stronger requirements -- for example if your + security policy requires verification that plaintext is not leaked + during startup or under various anomolous conditions -- then you will + need to devise much more thorough tests. If you do that, please post + any results or methodological details which your security policy allows + you to make public.

You can put recognizable data into ping packets with something like:

        ping -p feedfacedeadbeef 11.0.1.1

"feedfacedeadbeef" is a legal hexadecimal pattern that is easy to + pick out of hex dumps.

For other protocols, you may need to check if you have encrypted data + or ASCII text. Encrypted data has approximately equal frequencies for + all 256 possible characters. ASCII text has most characters in the + printable range 0x20-0x7f, a few control characters less than 0x20, and + none at all in the range 0x80-0xff. 0x20, space, is a good character to + look for. In normal English text space occurs about once in seven + characters, versus about once in 256 for random or encrypted data.

One thing to watch for: the output of good compression, like that of + good encryption, looks just like random noise. You cannot tell just by + looking at a data stream whether it has been compressed, encrypted, or + both. You need a little care not to mistake compressed data for + encrypted data in your testing.

Note also that weak encryption also produces random-looking output. + You cannot tell whether the encryption is strong by looking at the + output. To be sure of that, you would need to have both the algorithms + and the implementation examined by experts.

For IPsec, you can get partial assurance from interoperability tests. + See our interop document. When twenty + products all claim to implement 3DES, + and they all talk to each other, you can be fairly sure they have it + right. Of course, you might wonder whether all the implementers are + consipring to trick you or, more plausibly, whether some + implementations might have "back doors" so they can get also it wrong + when required.. If you're seriously worried about things like that, you + need to get the code you use audited (good luck if it is not Open + Source), or perhaps to talk to a psychiatrist about treatments for + paranoia.

Mailing list pointers

Additional information on testing can be found in these + mailing list messages:

a user's detailed + setup diary for his testbed network
a FreeS/WAN team member's + notes from testing at an IPsec interop "bakeoff"

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