denozord/strongswan-ext
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
ff8a0c2107d52db93d9145229e8142220675a882
strongswan-ext/doc/trouble.html
T
Martin Willi 997358a6c4 - import of strongswan-2.7.0 
- applied patch for charon
2006-04-28 07:14:48 +00:00

707 lines
36 KiB
HTML
Raw Blame History

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<HTML>
<HEAD>
<TITLE>Introduction to FreeS/WAN</TITLE>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; CHARSET=iso-8859-1">
<STYLE TYPE="text/css"><!--
BODY { font-family: serif }
H1 { font-family: sans-serif }
H2 { font-family: sans-serif }
H3 { font-family: sans-serif }
H4 { font-family: sans-serif }
H5 { font-family: sans-serif }
H6 { font-family: sans-serif }
SUB { font-size: smaller }
SUP { font-size: smaller }
PRE { font-family: monospace }
--></STYLE>
</HEAD>
<BODY>
<A HREF="toc.html">Contents</A>
<A HREF="firewall.html">Previous</A>
<A HREF="compat.html">Next</A>
<HR>
<H1><A NAME="trouble"></A>Linux FreeS/WAN Troubleshooting Guide</H1>
<H2><A NAME="overview"></A>Overview</H2>
<P> This document covers several general places where you might have a
problem:</P>
<OL>
<LI><A HREF="#install">During install</A>.</LI>
<LI><A HREF="#negotiation">During the negotiation process</A>.</LI>
<LI><A HREF="#use">Using an established connection</A>.</LI>
</OL>
<P>This document also contains<A HREF="#notes"> notes</A> which expand
on points made in these sections, and tips for<A HREF="#prob.report">
problem reporting</A>. If the other end of your connection is not
FreeS/WAN, you'll also want to read our<A HREF="interop.html#interop.problem">
interoperation</A> document.</P>
<H2><A NAME="install"></A>1. During Install</H2>
<H3><A NAME="8_2_1">1.1 RPM install gotchas</A></H3>
<P>With the RPM method:</P>
<UL>
<LI>Be sure you have installed both the userland tools and the kernel
components. One will not work without the other. For example, when
using FreeS/WAN-produced RPMs for our 2.04 release, you need both:
<PRE> freeswan-userland-2.04_2.4.20_20.9-0.i386.rpm
freeswan-module-2.04_2.4.20_20.9-0.i386.rpm
</PRE>
</LI>
</UL>
<H3><A NAME="8_2_2">1.2 Problems installing from source</A></H3>
<P>When installing from source, you may find these problems:</P>
<UL>
<LI>Missing library. See<A HREF="faq.html#gmp.h_missing"> this</A> FAQ.</LI>
<LI>Missing utilities required for compile. See this<A HREF="install.html#tool.lib">
checklist</A>.</LI>
<LI>Kernel version incompatibility. See<A HREF="faq.html#k.versions">
this</A> FAQ.</LI>
<LI>Another compile problem. Find information in the out.* files, ie.
out.kpatch, out.kbuild, created at compile time in the top-level Linux
FreeS/WAN directory. Error messages generated by KLIPS during the boot
sequence are accessible with the<VAR> dmesg</VAR> command.
<BR> Check the list archives and the List in Brief to see if this is a
known issue. If it is not, report it to the bugs list as described in
our<A HREF="#prob.report"> problem reporting</A> section. In some
cases, you may be asked to provide debugging information using gdb;
details<A HREF="#gdb"> below</A>.</LI>
<LI>If your kernel compiles but you fail to install your new
FreeS/WAN-enabled kernel, review the sections on<A HREF="install.html#newk">
installing the patched kernel</A>, and<A HREF="install.html#testinstall">
testing</A> to see if install succeeded.</LI>
</UL>
<H3><A NAME="install.check"></A>1.3 Install checks</H3>
<P><VAR>ipsec verify</VAR> checks a number of FreeS/WAN essentials. Here
are some hints on what do to when your system doesn't check out:</P>
<P></P>
<TABLE border="1">
<TR><TD><STRONG>Problem</STRONG></TD><TD><STRONG>Status</STRONG></TD><TD>
<STRONG>Action</STRONG></TD></TR>
<TR><TD><VAR>ipsec</VAR> not on-path</TD><TD>&nbsp;</TD><TD>
<P>Add<VAR> /usr/local/sbin</VAR> to your PATH.</P>
</TD></TR>
<TR><TD>Missing KLIPS support</TD><TD><FONT COLOR="#FF0000">critical</FONT>
</TD><TD>See<A HREF="faq.html#noKLIPS"> this FAQ.</A></TD></TR>
<TR><TD>No RSA private key</TD><TD>&nbsp;</TD><TD>
<P>Follow<A HREF="install.html#genrsakey"> these instructions</A> to
create an RSA key pair for your host. RSA keys are:</P>
<UL>
<LI>required for opportunistic encryption, and</LI>
<LI>our preferred method to authenticate pre-configured connections.</LI>
</UL>
</TD></TR>
<TR><TD><VAR>pluto</VAR> not running</TD><TD><FONT COLOR="#FF0000">
critical</FONT></TD><TD>
<PRE>service ipsec start</PRE>
</TD></TR>
<TR><TD>No port 500 hole</TD><TD><FONT COLOR="#FF0000">critical</FONT></TD><TD>
Open port 500 for IKE negotiation.</TD></TR>
<TR><TD>Port 500 check N/A</TD><TD>&nbsp;</TD><TD>Check that port 500 is open
for IKE negotiation.</TD></TR>
<TR><TD>Failed DNS checks</TD><TD>&nbsp;</TD><TD>Opportunistic encryption
requires information from DNS. To set this up, see<A HREF="quickstart.html#opp.setup">
our instructions</A>.</TD></TR>
<TR><TD>No public IP address</TD><TD>&nbsp;</TD><TD>Check that the interface
which you want to protect with IPSec is up and running.</TD></TR>
</TABLE>
<H3><A NAME="oe.trouble"></A>1.3 Troubleshooting OE</H3>
<P>OE should work with no local configuration, if you have posted DNS
TXT records according to the instructions in our<A HREF="quickstart.html">
quickstart guide</A>. If you encounter trouble, try these hints. We
welcome additional hints via the<A HREF="mail.html"> users' mailing
list</A>.</P>
<TABLE border="1">
<TR><TD><STRONG>Symptom</STRONG></TD><TD><STRONG>Problem</STRONG></TD><TD>
<STRONG>Action</STRONG></TD></TR>
<TR><TD> You're running FreeS/WAN 2.01 (or later), and initiating a
connection to FreeS/WAN 2.00 (or earlier). In your logs, you see a
message like:
<PRE>no RSA public key known for '192.0.2.13';
DNS search for KEY failed (no KEY record
for 13.2.0.192.in-addr.arpa.)</PRE>
The older FreeS/WAN logs no error.</TD><TD><A NAME="oe.trouble.flagday">
</A> A protocol level incompatibility between 2.01 (or later) and 2.00
(or earlier) causes this error. It occurs when a FreeS/WAN 2.01 (or
later) box for which no KEY record is posted attempts to initiate an OE
connection to older FreeS/WAN versions (2.00 and earlier). Note that
older versions can initiate to newer versions without this error.</TD><TD>
If you control the peer host, upgrade its FreeS/WAN to 2.01 (or later),
and post new style TXT records for it. If not, but if you know its
sysadmin, perhaps a quick note is in order. If neither option is
possible, you can ease the transition by posting an old style KEY
record (created with a command like &quot;ipsec&nbsp;showhostkey&nbsp;--key&quot;) to the
reverse map for the FreeS/WAN 2.01 (or later) box.</TD></TR>
<TR><TD>OE host is very slow to contact other hosts.</TD><TD>Slow DNS
service while running OE.</TD><TD>It's a good idea to run a caching DNS
server on your OE host, as outlined in<A HREF="http://lists.freeswan.org/pipermail/design/2003-January/004205.html">
this mailing list message</A>. If your DNS servers are elsewhere, put
their IPs in the<VAR> clear</VAR> policy group, and re-read groups with
<PRE>ipsec auto --rereadgroups</PRE>
</TD></TR>
<TR><TD>
<PRE>Can't Opportunistically initiate for
192.0.2.2 to 192.0.2.3: no TXT record
for 13.2.0.192.in-addr.arpa.</PRE>
</TD><TD>Peer is not set up for OE.</TD><TD>
<P>None. Plenty of hosts on the Internet do not run OE. If, however, you
have set OE up on that peer, this may indicate that you need to wait up
to 48 hours for its DNS records to propagate.</P>
</TD></TR>
<TR><TD><VAR>ipsec verify</VAR> does not find DNS records:
<PRE>...
Looking for TXT in forward map:
xy.example.com...[FAILED]
Looking for TXT in reverse map...[FAILED]
...</PRE>
You also experience authentication failure:
<BR>
<PRE>Possible authentication failure:
no acceptable response to our
first encrypted message</PRE>
</TD><TD>DNS records are not posted or have not propagated.</TD><TD>Did
you post the DNS records necessary for OE? If not, do so using the
instructions in our<A HREF="quickstart.html#quickstart"> quickstart
guide</A>. If so, wait up to 48 hours for the DNS records to propagate.</TD>
</TR>
<TR><TD><VAR>ipsec verify</VAR> does not find DNS records, and you
experience authentication failure.</TD><TD>For iOE, your ID does not
match location of forward DNS record.</TD><TD>In<VAR> config setup</VAR>
, change<VAR> myid=</VAR> to match the forward DNS where you posted the
record. Restart FreeS/WAN. For reference, see our<A HREF="quickstart.html#opp.client">
iOE instructions</A>.</TD></TR>
<TR><TD><VAR>ipsec verify</VAR> finds DNS records, yet there is still
authentication failure. ( ? )</TD><TD>DNS records are malformed.</TD><TD>
Re-create the records and send new copies to your DNS administrator.</TD>
</TR>
<TR><TD><VAR>ipsec verify</VAR> finds DNS records, yet there is still
authentication failure. ( ? )</TD><TD>DNS records show different keys
for a gateway vs. its subnet hosts.</TD><TD>All TXT records for boxes
protected by an OE gateway must contain the gateway's public key.
Re-create and re-post any incorrect records using<A HREF="quickstart.html#opp.incoming">
these instructions</A>.</TD></TR>
<TR><TD>OE gateway loses connectivity to its subnet. The gateway's
routing table shows routes to the subnet through IPsec interfaces.</TD><TD>
The subnet is part of the<VAR> private</VAR> or<VAR> block</VAR> policy
group on the gateway.</TD><TD>Remove the subnet from the group, and
reread groups with
<PRE>ipsec auto --rereadgroups</PRE>
</TD></TR>
<TR><TD>OE does not work to hosts on the local LAN.</TD><TD>This is a
known issue.</TD><TD>See<A HREF="opportunism.known-issues"> this list</A>
of known issues with OE.</TD></TR>
<TR><TD>FreeS/WAN does not seem to be executing your default policy. In
your logs, you see a message like:
<PRE>/etc/ipsec.d/policies/iprivate-or-clear&quot;
line 14: subnet &quot;0.0.0.0/0&quot;,
source 192.0.2.13/32,
already &quot;private-or-clear&quot;</PRE>
</TD><TD><A HREF="glossary.html#fullnet">Fullnet</A> in a policy group
file defines your default policy. Fullnet should normally be present in
only one policy group file. The fine print: you can have two default
policies defined so long as they protect different local endpoints
(e.g. the FreeS/WAN gateway and a subnet).</TD><TD> Find all policies
which contain fullnet with:
<BR>
<PRE>grep -F 0.0.0.0/0 /etc/ipsec.d/policies/*</PRE>
then remove the unwanted occurrence(s).</TD></TR>
</TABLE>
<H2><A NAME="negotiation"></A>2. During Negotiation</H2>
<P>When you fail to bring up a tunnel, you'll need to find out:</P>
<UL>
<LI><A HREF="#state">what your connection state is,</A> and often</LI>
<LI><A HREF="#find.pluto.error">an error message</A>.</LI>
</UL>
<P>before you can<A HREF="#interpret.pluto.error"> diagnose your problem</A>
.</P>
<H3><A NAME="state"></A>2.1 Determine Connection State</H3>
<H4>Finding current state</H4>
<P>You can see connection states (STATE_MAIN_I1 and so on) when you
bring up a connection on the command line. If you have missed this, or
brought up your connection automatically, use:</P>
<PRE>ipsec auto --status</PRE>
<P>The most relevant state is the last one reached.</P>
<H4><VAR>What's this supposed to look like?</VAR></H4>
<P>Negotiations should proceed though various states, in the processes
of:</P>
<OL>
<LI>IKE negotiations (aka Phase 1, Main Mode, STATE_MAIN_*)</LI>
<LI>IPSEC negotiations (aka Phase 2, Quick Mode, STATE_QUICK_*)</LI>
</OL>
<P>These are done and a connection is established when you see messages
like:</P>
<PRE> 000 #21: &quot;myconn&quot; STATE_MAIN_I4 (ISAKMP SA established)...
000 #2: &quot;myconn&quot; STATE_QUICK_I2 (sent QI2, IPsec SA established)...</PRE>
<P> Look for the key phrases are &quot;ISAKMP SA established&quot; and &quot;IPSec SA
established&quot;, with the relevant connection name. Often, this happens at
STATE_MAIN_I4 and STATE_QUICK_I2, respectively.</P>
<P><VAR>ipsec auto --status</VAR> will tell you what states<STRONG> have
been achieved</STRONG>, rather than the current state. Since
determining the current state is rather more difficult to do, current
state information is not available from Linux FreeS/WAN. If you are
actively bringing a connection up, the status report's last states for
that connection likely reflect its current state. Beware, though, of
the case where a connection was correctly brought up but is now downed:
Linux FreeS/WAN will not notice this until it attempts to rekey.
Meanwhile, the last known state indicates that the connection has been
established.</P>
<P>If your connection is stuck at STATE_MAIN_I1, skip straight to<A HREF="#ikepath">
here</A>.</P>
<H3><A NAME="find.pluto.error"></A>2.2 Finding error text</H3>
<P>Solving most errors will require you to find verbose error text,
either on the command line or in the logs.</P>
<H4>Verbose start for more information</H4>
<P> Note that you can get more detail from<VAR> ipsec auto</VAR> using
the --verbose flag:</P>
<PRE STYLE="margin-bottom: 0.2in"> ipsec auto --verbose --up west-east</PRE>
<P> More complete information can be gleaned from the<A HREF="#logusage">
log files</A>.</P>
<H4>Debug levels count</H4>
<P>The amount of description you'll get here depends on ipsec.conf debug
settings,<VAR> klipsdebug</VAR>= and<VAR> plutodebug</VAR>=. When
troubleshooting, set at least one of these to<VAR> all</VAR>, and when
done, reset it to<VAR> none</VAR> so your logs don't fill up. Note that
you must have enabled the<VAR> klipsdebug</VAR><A HREF="install.html#allbut">
compile-time option</A> for the<VAR> klipsdebug</VAR> configuration
switch to work.</P>
<P>For negotiation problems<VAR> plutodebug</VAR> is most relevant.<VAR>
klipsdebug</VAR> applies mainly to attempts to use an
already-established connection. See also<A HREF="ipsec.html#parts">
this</A> description of the division of duties within Linux FreeS/WAN.</P>
<P>After raising your debug levels, restart Linux FreeS/WAN to ensure
that ipsec.conf is reread, then recreate the error to generate verbose
logs.</P>
<H4><VAR>ipsec barf</VAR> for lots of debugging information</H4>
<P><A HREF="manpage.d/ipsec_barf.8.html"><VAR> ipsec barf (8)</VAR></A>
collects a bunch of useful debugging information, including these logs
Use the command</P>
<PRE>
ipsec barf &gt; barf.west
</PRE>
<P>to generate one.</P>
<H4>Find the error</H4>
<P>Search out the failure point in your logs. Are there a handful of
lines which succinctly describe how things are going wrong or contrary
to your expectation? Sometimes the failure point is not immediately
obvious: Linux FreeS/WAN's errors are usually not marked &quot;Error&quot;. Have
a look in the<A HREF="faq.html"> FAQ</A> for what some common failures
look like.</P>
<P>Tip: problems snowball. Focus your efforts on the first problem,
which is likely to be the cause of later errors.</P>
<H4>Play both sides</H4>
<P>Also find error text on the peer IPSec box. This gives you two
perspectives on the same failure.</P>
<P>At times you will require information which only one side has. The
peer can merely indicate the presence of an error, and its approximate
point in the negotiations. If one side keeps retrying, it may be
because there is a show stopper on the other side. Have a look at the
other side and figure out what it doesn't like.</P>
<P>If the other end is not Linux FreeS/WAN, the principle is the same:
replicate the error with its most verbose logging on, and capture the
output to a file.</P>
<H3><A NAME="interpret.pluto.error"></A>2.3 Interpreting a Negotiation
Error</H3>
<H4><A NAME="ikepath"></A>Connection stuck at STATE_MAIN_I1</H4>
<P>This error commonly happens because IKE (port 500) packets, needed to
negotiate an IPSec connection, cannot travel freely between your IPSec
gateways. See<A HREF="firewall.html#packets"> our firewall document</A>
for details.</P>
<H4>Other errors</H4>
<P>Other errors require a bit more digging. Use the following resources:</P>
<UL>
<LI><A HREF="faq.html">the FAQ</A> . Since this document is constantly
updated, the snapshot's FAQ may have a new entry relevant to your
problem.</LI>
<LI>our<A HREF="background.html"> background document</A> . Special
considerations which, while not central to Linux FreeS/WAN, are often
tripped over. Includes problems with<A href="background.html#MTU.trouble">
packet fragmentation</A>, and considerations for testing opportunism.</LI>
<LI>the<A HREF="mail.html#lists"> list archives</A>. Each of the
searchable archives works differently, so it's worth checking each. Use
a search term which is generic, but identifies your error, for example
&quot;No connection is known for&quot;.
<BR> Often, you will find that your question has been answered in the
past. Finding an archived answer is quicker than asking the list. You
may, however, find similar questions without answers. If you do, send
their URLs to the list with your trouble report. The additional
examples may help the list tech support person find your answer.</LI>
<LI>Look into the code where the error is being generated. The pluto
code is nicely documented with comments and meaningful variable names.</LI>
</UL>
<P>If you have failed to solve your problem with the help of these
resources, send a detailed problem report to the users list, following
these<A HREF="#prob.report"> guidelines</A>.</P>
<H2><A NAME="use"></A>3. Using a Connection</H2>
<H3><A NAME="8_4_1">3.1 Orienting yourself</A></H3>
<H4><VAR>How do I know if it works?</VAR></H4>
<P>Test your connection by sending packets through it. The simplest way
to do this is with ping, but the ping needs to<STRONG> test the correct
tunnel.</STRONG> See<A HREF="#testgates"> this example scenario</A> if
you don't understand this.</P>
<P></P>
<P>If your ping returns, test any other connections you've brought u all
check out, great. You may wish to<A HREF="#bigpacket"> test with large
packets</A> for MTU problems.</P>
<H4><VAR>ipsec barf</VAR> is useful again</H4>
<P>If your ping fails to return, generate an ipsec barf debugging report
on each IPSec gateway. On a non-Linux FreeS/WAN implementation, gather
equivalent information. Use this, and the tips in the next sections, to
troubleshoot. Are you sure that both endpoints are capable of hearing
and responding to ping?</P>
<H3><A NAME="8_4_2">3.2 Those pesky configuration errors</A></H3>
<P>IPSec may be dropping your ping packets since they do not belong in
the tunnels you have constructed:</P>
<UL>
<LI>Your ping may not test the tunnel you intend to test. For details,
see our<A HREF="faq.html#cantping"> &quot;I can't ping&quot;</A> FAQ.</LI>
<LI> Alternately, you may have a configuration error. For example, you
may have configured one of the four possible tunnels between two
gateways, but not the one required to secure the important traffic
you're now testing. In this case, add and start the tunnel, and try
again.</LI>
</UL>
<P>In either case, you will often see a message like:</P>
<PRE>klipsdebug... no eroute</PRE>
<P>which we discuss in<A HREF="faq.html#no_eroute"> this FAQ</A>.</P>
<P>Note:</P>
<UL>
<LI><A HREF="glossary.html#NAT.gloss">Network Address Translation (NAT)</A>
and<A HREF="glossary.html#masq"> IP masquerade</A> may have an effect
on which tunnels you need to configure.</LI>
<LI>When testing a tunnel that protects a multi-node subnet, try several
subnet nodes as ping targets, in case one node is routing incorrectly.</LI>
</UL>
<H3><A NAME="route.firewall"></A>3.3 Check Routing and Firewalling</H3>
<P>If you've confirmed your configuration assumptions, the problem is
almost certainly with routing or firewalling. Isolate the problem using
interface statistics, firewall statistics, or a packet sniffer.</P>
<H4>Background:</H4>
<UL>
<LI>Linux FreeS/WAN supplies all the special routing it needs; you need
only route packets out through your IPSec gateway. Verify that on the<VAR>
subnetted</VAR> machines you are using for your ping-test, your routing
is as expected. I have seen a tunnel &quot;fail&quot; because the subnet machine
sending packets out an alternate gateway (not our IPSec gateway) on
their return path.</LI>
<LI>Linux FreeS/WAN requires particular<A HREF="firewall.html">
firewalling considerations</A>. Check the firewall rules on your IPSec
gateways and ensure that they allow IPSec traffic through. Be sure that
no other machine - for example a router between the gateways - is
blocking your IPSec packets.</LI>
</UL>
<H4><A NAME="ifconfig"></A>View Interface and Firewall Statistics</H4>
<P>Interface reports and firewall statistics can help you track down
lost packets at a glance. Check any firewall statistics you may be
keeping on your IPSec gateways, for dropped packets.</P>
<P><STRONG>Tip</STRONG>: You can take a snapshot of the packets
processed by your firewall with:</P>
<PRE> iptables -L -n -v</PRE>
<P>You can get creative with &quot;diff&quot; to find out what happens to a
particular packet during transmission.</P>
<P>Both<VAR> cat /proc/net/dev</VAR> and<VAR> ifconfig</VAR> display
interface statistics, and both are included in<VAR> ipsec barf</VAR>.
Use either to check if any interface has dropped packets. If you find
that one has, test whether this is related to your ping. While you ping
continuously, print that interface's statistics several times. Does its
drop count increase in proportion to the ping? If so, check why the
packets are dropped there.</P>
<P>To do this, look at the firewall rules that apply to that interface.
If the interface is an IPSec interface, more information may be
available in the log. Grep for the word &quot;drop&quot; in a log which was
created with<VAR> klipsdebug=all</VAR> as the error happened.</P>
<P>See also this<A HREF="#ifconfig1"> discussion</A> on interpreting<VAR>
ifconfig</VAR> statistics.</P>
<H3><A NAME="sniff"></A>3.4 When in doubt, sniff it out</H3>
<P>If you have checked configuration assumptions, routing, and firewall
rules, and your interface statistics yield no clue, it remains for you
to investigate the mystery of the lost packet by the most thorough
method: with a packet sniffer (providing, of course, that this is legal
where you are working).</P>
<P>In order to detect packets on the ipsec virtual interfaces, you will
need an up-to-date sniffer (tcpdump, ethereal, ksnuffle) on your IPSec
gateway machines. You may also find it useful to sniff the ping
endpoints.</P>
<H4>Anticipate your packets' path</H4>
<P>Ping, and examine each interface along the projected path, checking
for your ping's arrival. If it doesn't get to the the next stop, you
have narrowed down where to look for it. In this way, you can isolate a
problem area, and narrow your troubleshooting focus.</P>
<P>Within a machine running Linux FreeS/WAN, this<A HREF="firewall.html#packets">
packet flow diagram</A> will help you anticipate a packet's path.</P>
<P>Note that:</P>
<UL>
<LI> from the perspective of the tunneled packet, the entire tunnel is
one hop. That's explained in<A HREF="faq.html#no_trace"> this</A> FAQ.</LI>
<LI> an encapsulated IPSec packet will look different, when sniffed,
from the plaintext packet which generated it. You can see plaintext
packets entering an IPSec interface and the resulting cyphertext
packets as they emerge from the corresponding physical interface.</LI>
</UL>
<P>Once you isolate where the packet is lost, take a closer look at
firewall rules, routing and configuration assumptions as they affect
that specific area. If the packet is lost on an IPSec gateway, comb
through<VAR> klipsdebug</VAR> output for anomalies.</P>
<P>If the packet goes through both gateways successfully and reaches the
ping target, but does not return, suspect routing. Check that the ping
target routes packets back to the IPSec gateway.</P>
<H3><A NAME="find.use.error"></A>3.5 Check your logs</H3>
<P>Here, too, log information can be useful. Start with the<A HREF="#find.pluto.error">
guidelines above</A>.</P>
<P>For connection use problems, set<VAR> klipsdebug=all</VAR>. Note that
you must have enabled the<VAR> klipsdebug</VAR><A HREF="install.html#allbut">
compile-time option</A> to do this. Restart Linux FreeS/WAN so that it
rereads<VAR> ipsec.conf</VAR>, then recreate the error condition. When
searching through<VAR> klipsdebug</VAR> data, look especially for the
keywords &quot;drop&quot; (as in dropped packets) and &quot;error&quot;.</P>
<P>Often the problem with connection use is not software error, but
rather that the software is behaving contrary to expectation.</P>
<H4><A NAME="interpret.use.error"></A>Interpreting log text</H4>
<P>To interpret the Linux FreeS/WAN log text you've found, use the same
resources as indicated for troubleshooting connection negotiation:<A HREF="faq.html">
the FAQ</A> , our<A HREF="background.html"> background document</A>,
and the<A HREF="mail.html#lists"> list archives</A>. Looking in the
KLIPS code is only for the very brave.</P>
<P>If you are still stuck, send a<A HREF="#prob.report"> detailed
problem report</A> to the users' list.</P>
<H3><A NAME="bigpacket"></A>3.6 More testing for the truly thorough</H3>
<H4>Large Packets</H4>
<P>If each of your connections passed the ping test, you may wish to
test by pinging with large packets (2000 bytes or larger). If it does
not return, suspect MTU issues, and see this<A HREF="background.html#MTU.trouble">
discussion</A>.</P>
<H4>Stress Tests</H4>
<P>In most users' view, a simple ping test, and perhaps a large-packet
ping test suffice to indicate a working IPSec connection.</P>
<P>Some people might like to do additional stress tests prior to
production use. They may be interested in this<A HREF="http://www.sandelman.ottawa.on.ca/linux-ipsec/html/2000/12/msg00224.html">
testing protocol</A> we use at interoperation conferences, aka
&quot;bakeoffs&quot;. We also have a<VAR> testing</VAR> directory that ships with
the release.</P>
<H2><A NAME="prob.report"></A>4. Problem Reporting</H2>
<H3><A NAME="8_5_1">4.1 How to ask for help</A></H3>
<P>Ask for troubleshooting help on the users' mailing list,<A HREF="mailto:[email protected]">
[email protected]</A>. While sometimes an initial query with a
quick description of your intent and error will twig someone's memory
of a similar problem, it's often necessary to send a second mail with a
complete problem report.</P>
<P>When reporting problems to the mailing list(s), please include:</P>
<UL>
<LI>a brief description of the problem</LI>
<LI>if it's a compile problem, the actual output from make, showing the
problem. Try to edit it down to only the relevant part, but when in
doubt, be as complete as you can. If it's a kernel compile problem, any
relevant out.* files</LI>
<LI>if it's a run-time problem, pointers to where we can find the
complete output from &quot;ipsec barf&quot; from BOTH ENDS (not just one of
them). Remember that it's common outside the US and Canada to pay for
download volume, so if you can't post barfs on the web and send the URL
to the mailing list, at least compress them with tar or gzip.
<BR> If you can, try to simplify the case that is causing the problem.
In particular, if you clear your logs, start FreeS/WAN with no other
connections running, cause the problem to happen, and then do<VAR>
ipsec barf</VAR> on both ends immediately, that gives the smallest and
least cluttered output.</LI>
<LI>any other error messages, complaints, etc. that you saw. Please send
the complete text of the messages, not just a summary.</LI>
<LI>what your network setup is. Include subnets, gateway addresses, etc.
A schematic diagram is a good format for this information.</LI>
<LI>exactly what you were trying to do with Linux FreeS/WAN, and exactly
what went wrong</LI>
<LI>a fix, if you have one. But remember, you are sending mail to people
all over the world; US residents and US citizens in particular, please
read doc/exportlaws.html before sending code -- even small bug fixes --
to the list or to us.</LI>
<LI>When in doubt about whether to include some seemingly-trivial item
of information, include it. It is rare for problem reports to have too
much information, and common for them to have too little.</LI>
</UL>
<P>Here are some good general guidelines on bug reporting:<A href="http://tuxedo.org/~esr/faqs/smart-questions.html">
How To Ask Questions The Smart Way</A> and<A href="http://www.chiark.greenend.org.uk/~sgtatham/bugs.html">
How to Report Bugs Effectively</A>.</P>
<H3><A NAME="8_5_2">4.2 Where to ask</A></H3>
<P>To report a problem, send mail about it to the users' list. If you
are certain that you have found a bug, report it to the bugs list. If
you encounter a problem while doing your own coding on the Linux
FreeS/WAN codebase and think it is of interest to the design team,
notify the design list. When in doubt, default to the users' list. More
information about the mailing lists is found<A HREF="mail.html#lists">
here</A>.</P>
<P>For a number of reasons -- including export-control regulations
affecting almost any<STRONG> private</STRONG> discussion of encryption
software -- we prefer that problem reports and discussions go to the
lists, not directly to the team. Beware that the list goes worldwide;
US citizens, read this important information about your<A HREF="politics.html#exlaw">
export laws</A>. If you're using this software, you really should be on
the lists. To get onto them, visit<A HREF="http://lists.freeswan.org/">
lists.freeswan.org</A>.</P>
<P>If you do send private mail to our coders or want a private reply
from them, please make sure that the return address on your mail (From
or Reply-To header) is a valid one. They have more important things to
do than to unravel addresses that have been mangled in an attempt to
confuse spammers.</P>
<H2><A NAME="notes"></A>5. Additional Notes on Troubleshooting</H2>
<P>The following sections supplement the Guide:<A HREF="#system.info">
information available on your system</A>;<A HREF="#testgates"> testing
between security gateways</A>;<A HREF="#ifconfig1"> ifconfig reports
for KLIPS debugging</A>;<A HREF="#gdb"> using GDB on Pluto</A>.</P>
<H3><A NAME="system.info"></A>5.1 Information available on your system</H3>
<H4><A NAME="logusage"></A>Logs used</H4>
<P>Linux FreeS/WAN logs to:</P>
<UL>
<LI>/var/log/secure (or, on Debian, /var/log/auth.log)</LI>
<LI>/var/log/messages</LI>
</UL>
<P>Check both places to get full information. If you find nothing, check
your<VAR> syslogd.conf(5)</VAR> to see where your /etc/syslog.conf or
equivalent is directing<VAR> authpriv</VAR> messages.</P>
<H4><A NAME="pages"></A>man pages provided</H4>
<DL>
<DT><A HREF="manpage.d/ipsec.conf.5.html">ipsec.conf(5)</A></DT>
<DD> Manual page for IPSEC configuration file.</DD>
<DT><A HREF="manpage.d/ipsec.8.html"> ipsec(8)</A></DT>
<DD STYLE="margin-bottom: 0.2in"> Primary man page for ipsec utilities.</DD>
</DL>
<P> Other man pages are on<A HREF="manpages.html"> this list</A> and in</P>
<UL>
<LI>/usr/local/man/man3</LI>
<LI>/usr/local/man/man5</LI>
<LI>/usr/local/man/man8/ipsec_*</LI>
</UL>
<H4><A NAME="statusinfo"></A>Status information</H4>
<DL>
<DT>ipsec auto --status</DT>
<DD> Command to get status report from running system. Displays Pluto's
state. Includes the list of connections which are currently &quot;added&quot; to
Pluto's internal database; lists state objects reflecting ISAKMP and
IPsec SAs being negotiated or installed.</DD>
<DT> ipsec look</DT>
<DD> Brief status info.</DD>
<DT> ipsec barf</DT>
<DD STYLE="margin-bottom: 0.2in"> Copious debugging info.</DD>
</DL>
<H3><A NAME="testgates"></A> 5.2 Testing between security gateways</H3>
<P>Sometimes you need to test a subnet-subnet tunnel. This is a tunnel
between two security gateways, which protects traffic on behalf of the
subnets behind these gateways. On this network:</P>
<PRE> Sunset==========West------------------East=========Sunrise
IPSec gateway IPSec gateway
local net untrusted net local net</PRE>
<P> you might name this tunnel sunset-sunrise. You can test this tunnel
by having a machine behind one gateway ping a machine behind the other
gateway, but this is not always convenient or even possible.</P>
<P>Simply pinging one gateway from the other is not useful. Such a ping
does not normally go through the tunnel.<STRONG> The tunnel handles
traffic between the two protected subnets, not between the gateways</STRONG>
. Depending on the routing in place, a ping might</P>
<UL>
<LI>either succeed by finding an unencrypted route</LI>
<LI>or fail by finding no route. Packets without an IPSEC eroute are
discarded.</LI>
</UL>
<P><STRONG>Neither event tells you anything about the tunnel</STRONG>.
You can explicitly create an eroute to force such packets through the
tunnel, or you can create additional tunnels as described in our<A HREF="config.html#multitunnel">
configuration document</A>, but those may be unnecessary complications
in your situation.</P>
<P>The trick is to explicitly test between<STRONG> both gateways'
private-side IP addresses</STRONG>. Since the private-side interfaces
are on the protected subnets, the resulting packets do go via the
tunnel. Use either ping -I or traceroute -i, both of which allow you to
specify a source interface. (Note: unsupported on older Linuxes). The
same principles apply for a road warrior (or other) case where only one
end of your tunnel is a subnet.</P>
<H3><A NAME="ifconfig1"></A>5.3 ifconfig reports for KLIPS debugging</H3>
<P>When diagnosing problems using ifconfig statistics, you may wonder
what type of activity increments a particular counter for an ipsecN
device. Here's an index, posted by KLIPS developer Richard Guy Briggs:</P>
<PRE>Here is a catalogue of the types of errors that can occur for which
statistics are kept when transmitting and receiving packets via klips.
I notice that they are not necessarily logged in the right counter.
. . .
Sources of ifconfig statistics for ipsec devices
rx-errors:
- packet handed to ipsec_rcv that is not an ipsec packet.
- ipsec packet with payload length not modulo 4.
- ipsec packet with bad authenticator length.
- incoming packet with no SA.
- replayed packet.
- incoming authentication failed.
- got esp packet with length not modulo 8.
tx_dropped:
- cannot process ip_options.
- packet ttl expired.
- packet with no eroute.
- eroute with no SA.
- cannot allocate sk_buff.
- cannot allocate kernel memory.
- sk_buff internal error.
The standard counters are:
struct enet_statistics
{
int rx_packets; /* total packets received */
int tx_packets; /* total packets transmitted */
int rx_errors; /* bad packets received */
int tx_errors; /* packet transmit problems */
int rx_dropped; /* no space in linux buffers */
int tx_dropped; /* no space available in linux */
int multicast; /* multicast packets received */
int collisions;
/* detailed rx_errors: */
int rx_length_errors;
int rx_over_errors; /* receiver ring buff overflow */
int rx_crc_errors; /* recved pkt with crc error */
int rx_frame_errors; /* recv'd frame alignment error */
int rx_fifo_errors; /* recv'r fifo overrun */
int rx_missed_errors; /* receiver missed packet */
/* detailed tx_errors */
int tx_aborted_errors;
int tx_carrier_errors;
int tx_fifo_errors;
int tx_heartbeat_errors;
int tx_window_errors;
};
of which I think only the first 6 are useful.</PRE>
<H3><A NAME="gdb"></A> 5.4 Using GDB on Pluto</H3>
<P>You may need to use the GNU debugger, gdb(1), on Pluto. This should
be necessary only in unusual cases, for example if you encounter a
problem which the Pluto developer cannot readily reproduce or if you
are modifying Pluto.</P>
<P>Here are the Pluto developer's suggestions for doing this:</P>
<PRE>Can you get a core dump and use gdb to find out what Pluto was doing
when it died?
To get a core dump, you will have to set dumpdir to point to a
suitable directory (see <A HREF="manpage.d/ipsec.conf.5.html">ipsec.conf(5)</A>).
To get gdb to tell you interesting stuff:
$ script
$ cd dump-directory-you-chose
$ gdb /usr/local/lib/ipsec/pluto core
(gdb) where
(gdb) quit
$ exit
The resulting output will have been captured by the script command in
a file called &quot;typescript&quot;. Send it to the list.
Do not delete the core file. I may need to ask you to print out some
more relevant stuff.</PRE>
<P> Note that the<VAR> dumpdir</VAR> parameter takes effect only when
the IPsec subsystem is restarted -- reboot or ipsec setup restart.</P>
<P>
<BR>
<BR></P>
<HR>
<A HREF="toc.html">Contents</A>
<A HREF="firewall.html">Previous</A>
<A HREF="compat.html">Next</A>
</BODY>
</HTML>
Reference in New Issue View Git Blame Copy Permalink