File: trouble.html

package info (click to toggle)
openswan 1%3A2.6.37-3%2Bdeb7u1
links: PTS, VCS
area: main
in suites: wheezy
size: 67,676 kB
sloc: ansic: 188,979; sh: 44,975; xml: 17,253; perl: 4,787; asm: 4,422; makefile: 3,287; tcl: 1,515; objc: 1,080; yacc: 771; exp: 643; lex: 580; pascal: 469; python: 356; sed: 251; lisp: 3
file content (706 lines) | stat: -rw-r--r-- 37,010 bytes
<!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 2.03 release, you need both:
<PRE>    freeswan-userland-2.03_2.4.20_20.9-0.i386.rpm
    freeswan-module-2.03_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:users@lists.freeswan.org">
 users@lists.freeswan.org</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/share/man/man3/ipsec_*</LI>
<LI>/usr/share/man/man5/ipsec_*</LI>
<LI>/usr/share/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/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>