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<p style="text-align: center; background: #ccc; border: 1px solid #2d5588;"><a 
   style="text-decoration: none;" 
   href="http://www.la-samhna.de/samhain/">samhain file integrity 
   scanner</a>&nbsp;|&nbsp;<a style="text-decoration: none;" 
   href="http://www.la-samhna.de/samhain/s_documentation.html">online 
   documentation</a></p>
<br><center><h1><a name="FAQ-top">Frequently Asked Questions for Samhain</a></h1></center>
<br><center><h2>Rainer Wichmann</h2></center>
<hr>
<div class="warnblock">
<ul>
  <li>If you encounter problems after installing samhain, disable daemon
      mode and run it in the foreground with 
      <tt>samhain --foreground [more options]</tt> for debugging.</li>
  <li>If you have problems getting client/server mode to work, please check
      the <a href="http://www.la-samhna.de/samhain/HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a> document.</li>
</ul>
</div>
<p><i>FAQ Revised: Saturday 14 April 2007 17:05:58</i></p>
<hr><h2>Table of Contents</h2>
<dl>
<dt><b>1. Most frequently</b></dt>
<dd><ul>
<li><a href="#Most frequently0">1.1. Owner not trustworthy / Group writeable and member not trustworthy</a></li>
<li><a href="#Most frequently1">1.2. samhain exits with the message &quot;Untrusted path&quot; for config/log/pid/database files</a></li>
<li><a href="#Most frequently2">1.3. It does not log anything / Can't stop logging to console</a></li>
<li><a href="#Most frequently3">1.4. Client cannot self-resolve, but nslookup works fine</a></li>
</ul></dd>
<dt><b>2. Build and install</b></dt>
<dd><ul>
<li><a href="#Build and install0">2.1. [Fedora Core] Cannot compile with --enable-khide</a></li>
<li><a href="#Build and install1">2.2. [Fedora Core] Cannot compile with --with-kcheck</a></li>
<li><a href="#Build and install2">2.3. &quot;make&quot; loops infinitely !</a></li>
<li><a href="#Build and install3">2.4. Why does static compiling (<code>--enable-static</code>) on Solaris fail ?</a></li>
<li><a href="#Build and install4">2.5. Compilation fails with '/usr/bin/ld: cannot find -lnss_files'</a></li>
<li><a href="#Build and install5">2.6. The executable is corrupted after installation</a></li>
<li><a href="#Build and install6">2.7. --enable-xml-log has no effect</a></li>
<li><a href="#Build and install7">2.8. ./install-sh: strip: not found (Solaris)</a></li>
<li><a href="#Build and install8">2.9. What is sh_tiger1.s?</a></li>
<li><a href="#Build and install9">2.10. Why does static compiling (<code>--enable-static</code>) on MaxOS X fail ?</a></li>
<li><a href="#Build and install10">2.11. Why does compiling with MySQL fail on Solaris ?</a></li>
</ul></dd>
<dt><b>3. File checking</b></dt>
<dd><ul>
<li><a href="#File checking0">3.1. How can I exclude a (sub-)directory ?</a></li>
<li><a href="#File checking1">3.2. In messages about policy violations, what does the code after POLICY [XYZ] 
mean ?</a></li>
<li><a href="#File checking2">3.3. Does samhain support prelink ?</a></li>
<li><a href="#File checking3">3.4. I get error messages about 'subdirectory count != hardlinks'</a></li>
</ul></dd>
<dt><b>4. Client/Server</b></dt>
<dd><ul>
<li><a href="#Client/Server0">4.1. I don't want to poke a hole into my firewall to let the client connect to the server !</a></li>
<li><a href="#Client/Server1">4.2. The client sends 127.0.0.1 (or some other numerical address) as its name to the log server</a></li>
<li><a href="#Client/Server2">4.3. The server wants to send rc.ip-adress rather than rc.fqdn to the client</a></li>
<li><a href="#Client/Server3">4.4. Cannot resolve client name host=XXX</a></li>
<li><a href="#Client/Server4">4.5. Cannot resolve socket peer IP for client host=XXX peer=YYY</a></li>
<li><a href="#Client/Server5">4.6. Reverse lookup of socket peer failed host=XXX peer=YYY obj=ZZZ</a></li>
<li><a href="#Client/Server6">4.7. No socket peer alias matches client name host=XXX peer=YYY</a></li>
<li><a href="#Client/Server7">4.8. Session key negotiation failed</a></li>
<li><a href="#Client/Server8">4.9. Invalid connection attempt: Not in client list</a></li>
<li><a href="#Client/Server9">4.10. Invalid connection attempt: Session key mismatch</a></li>
<li><a href="#Client/Server10">4.11. How do I update the file signature database ?</a></li>
<li><a href="#Client/Server11">4.12. Time limit exceeded</a></li>
<li><a href="#Client/Server12">4.13. Invalid connection attempt:  Signature mismatch</a></li>
<li><a href="#Client/Server13">4.14. [Server] PANIC .. Address already in use&nbsp; &nbsp;subroutine=bind</a></li>
</ul></dd>
<dt><b>5. Email</b></dt>
<dd><ul>
<li><a href="#Email0">5.1. Reverse lookup failed</a></li>
<li><a href="#Email1">5.2. From daemon@example.com</a></li>
<li><a href="#Email2">5.3. How do I define more than one email addresses ?</a></li>
</ul></dd>
<dt><b>6. Misc</b></dt>
<dd><ul>
<li><a href="#Misc0">6.1. Error message: &quot;Invalid line XYZ in configuration file&quot;</a></li>
<li><a href="#Misc1">6.2. Why do I get a local logfile if I log to the server ?</a></li>
<li><a href="#Misc2">6.3. Why is there no NIS support with a static samhain executable on Linux ?</a></li>
<li><a href="#Misc3">6.4. Why do I get hundreds of messages about modified CTIME ?</a></li>
<li><a href="#Misc4">6.5. PANIC &mdash; File not accessible</a></li>
<li><a href="#Misc5">6.6. How can I avoid error messages for invalid UIDs (no such user) ?</a></li>
<li><a href="#Misc6">6.7. [Redhat] The /etc/init.d/(samhain|yule) init script hangs</a></li>
<li><a href="#Misc7">6.8. The /etc/init.d/(samhain|yule) init script exits with: execvp: No such file or directory</a></li>
<li><a href="#Misc8">6.9. Why am I not receiving the &quot;BEGIN LOGKEY&quot; message by email ?</a></li>
<li><a href="#Misc9">6.10. Why does console logging fail if I compile with 
   <code>--enable-(micro-)stealth</code> ?</a></li>
<li><a href="#Misc10">6.11. I need a list for my schedule !</a></li>
<li><a href="#Misc11">6.12. The hiding kernel module has no effect !</a></li>
<li><a href="#Misc12">6.13. What does the message &quot;Large lstat/open overhead&quot; mean ?</a></li>
<li><a href="#Misc13">6.14. What does the message &quot;Device not available path=/dev/random&quot; mean ? I have /dev/random !</a></li>
<li><a href="#Misc14">6.15. Logging to an external program fails; the program receives no data 
   on stdin !</a></li>
<li><a href="#Misc15">6.16. SIGILL on AIX</a></li>
</ul></dd>
<dt><b>7. Database</b></dt>
<dd><ul>
<li><a href="#Database0">7.1. Why are client messages corrupted / incompletely stored in the DB ?</a></li>
<li><a href="#Database1">7.2. I want / don't want the server timestamps (for client messages) in the SQL database</a></li>
<li><a href="#Database2">7.3. I don't want the client TIMESTAMP messages in the SQL database</a></li>
<li><a href="#Database3">7.4. What does the log_ref field mean ?</a></li>
<li><a href="#Database4">7.5. How can I check what is in the database ?</a></li>
</ul></dd>
</dl>
<hr><h2>1. Most frequently</h2>
<dl>
<dt><b><a name="Most frequently0">1.1. Owner not trustworthy / Group writeable and member not trustworthy</a></b></dt>
<dd>An untrusted user (might be an untrusted group member
        for group writeable files/directories) owns or can write to an
        element in the path listed in the error message. This concerns
        the configuration file, the log file, and the database file.
        The offending element in the path is identified as obj=/xxx in the
        error message.
	To fix the problem, see next entry.<br><br></dd>
<dt><b><a name="Most frequently1">1.2. samhain exits with the message &quot;Untrusted path&quot; for config/log/pid/database files</a></b></dt>
<dd>Paths to critical
   files (e.g. the configuration file) must be writeable by trusted users
   only.   
   If a path element is group writeable, all group members must be trusted.
   By default, only <i>root</i> and the (effective) <i>user</i> of
   the program are trusted. To add trusted users, use the compile time
   option
<div class="block"><pre>
$ ./configure --with-trusted=0,...
</pre></div>
   or the configure file option:
<div class="block"><pre>
[Misc]
TrustedUser=username
</pre></div>
If the path to the configuration file itself is writeable 
  by other users than <i>root</i> and the 
  <i>effective user</i>
  these must be defined as trusted already
  at compile time.<br><br></dd>
<dt><b><a name="Most frequently2">1.3. It does not log anything / Can't stop logging to console</a></b></dt>
<dd>(1) There is a section in the manual dealing with
logging and filtering.<br />

(2) To log to the console:
<div class="block"><pre>
$ samhain -p info ...
</pre></div>
or in the configuration file:
<div class="block"><pre>
[Log]
PrintSeverity=info
</pre></div>

To <i>stop</i> logging to the console:
<div class="block"><pre>
$ samhain -p none ...
</pre></div>
or in the configuration file:
<div class="block"><pre>
[Log]
PrintSeverity=none
</pre></div>
Defining <tt>/dev/null</tt> as console device works as well, but 
is a bad idea, because samhain will open the device and write (i.e. it is
a very inefficient method).<br><br></dd>
<dt><b><a name="Most frequently3">1.4. Client cannot self-resolve, but nslookup works fine</a></b></dt>
<dd><ul>
<li>Nslookup is  a program to query Internet domain name servers.
</li>
<li>Applications (like samhain) are not supposed to query DNS servers
 directly. Rather, they are supposed to query the resolver library that:
  <ul>
   <li>is provided by the operating system,</li>
   <li>configured by the system administrator,</li>
   <li>may use several different method to determine host names, as
       configured in <tt>/etc/nsswitch.conf</tt>, and</li>
   <li>usually is configured to give precedence to 
       the <tt>/etc/hosts</tt> file.</li>
  </ul>
</li>
<li>Therefore, whether nslookup gives correct answers may be completely 
    irrelevant. For self-resolving the own hostname, the resolver
    library probably will use <tt>/etc/hosts</tt>, rather than 
    querying a DNS server.
</li>
</ul>
<p>
Below you can find some examples of good and bad <tt>/etc/hosts</tt> files:
</p>
<div class="block"><pre>
        # CORRECT
	#
        127.0.0.1  localhost
        xxx.xxx.xxx.xxx myhost.mydomain.tld  myhost
</pre></div>

<div class="block"><pre>
        # CORRECT
	#
        127.0.0.1  localhost.localdomain localhost
        xxx.xxx.xxx.xxx myhost.mydomain.tld  myhost
</pre></div>

<div class="block"><pre>
        # BAD
	#
        127.0.0.1  myhost.mydomain.tld  localhost
        xxx.xxx.xxx.xxx myhost.mydomain.tld  myhost
</pre></div>

<div class="block"><pre>
        # BAD
	#
        127.0.0.1  localhost myhost
        xxx.xxx.xxx.xxx myhost.mydomain.tld  myhost
</pre></div><br><br></dd>
</dl>
<hr><h2>2. Build and install</h2>
<dl>
<dt><b><a name="Build and install0">2.1. [Fedora Core] Cannot compile with --enable-khide</a></b></dt>
<dd>The Fedora Core kernel is patched to unconditionally deny reading
from /dev/kmem. Compiling the stealth kernel modules is not possible
under these circumstances.<br><br></dd>
<dt><b><a name="Build and install1">2.2. [Fedora Core] Cannot compile with --with-kcheck</a></b></dt>
<dd>The Fedora Core kernel is patched to unconditionally deny reading
from /dev/kmem. Checking the kernel for the presence of rootkits is
not possible under these circumstances.<br><br></dd>
<dt><b><a name="Build and install2">2.3. &quot;make&quot; loops infinitely !</a></b></dt>
<dd>This may happen (e.g. when building via NFS for multiple architectures) 
   if the relative timestamps in the source directory are
   wrong (time not in sync on different machines) or some intermediate
   target is unusable (up-to-date, but built for a different OS). Use
   &quot;touch * &amp;&amp; make distclean&quot; in the source directory
   to recover.<br><br></dd>
<dt><b><a name="Build and install3">2.4. Why does static compiling (<code>--enable-static</code>) on Solaris fail ?</a></b></dt>
<dd>Ingo Rogalsky has provided the following information: It isn't possible 
   to link Samhain statically with Solaris. This
   is a Solaris issue (see Sun Infodoc ID12624) and not a samhain problem.<br><br></dd>
<dt><b><a name="Build and install4">2.5. Compilation fails with '/usr/bin/ld: cannot find -lnss_files'</a></b></dt>
<dd>For Linux, this is a known problem with --enable-static if you compile
     in MySQL support. The problem is that the 
     <tt>mysql_config</tt> that comes as part of the MySQL
     distribution script incorrectly lists dependencies on 
     the libnss_files and libnss_dns libraries which are only available as
     shared libraries, so the linker cannot find the static libraries.

     You can check this by inspecting the output of 
     <code>mysql_config --libs</code>. The version of 
     <tt>mysql_config</tt> that comes with the RedHat mysql
     RPM (RedHat 9) does not have this bug; the one distributed by the MySQL
     people has. You can fix the problem by editing 
     <tt>mysql_config</tt>: search for the 
     <i>client_libs</i> variable, and remove all instances 
     of <i>-lnss_files</i> and <i>-lnss_dns</i>.<br><br></dd>
<dt><b><a name="Build and install5">2.6. The executable is corrupted after installation</a></b></dt>
<dd>The executable will get stripped during the installation. On
        suitable systems (i386 Linux/FreeBSD currently), additionally 
        the &quot;sstrip&quot;
        utility (copyright 1999 by Brian Raiter, under the GNU GPL) 
        will be used to strip the executable even more, to prevent 
        debugging with the GNU &quot;gdb&quot; debugger.
        The &quot;strip&quot; utility cannot handle the resulting
        executable, therefore trying to strip manually after installation
        will corrupt the executable.<br><br></dd>
<dt><b><a name="Build and install6">2.7. --enable-xml-log has no effect</a></b></dt>
<dd>If you have compiled for stealth, you won't see much, because if
        obfuscated, then both a 'normal' and an XML logfile look,
        well ... obfuscated. Use <code>samhain -jL /path/to/logfile</code>
        to view the logfile.<br><br></dd>
<dt><b><a name="Build and install7">2.8. ./install-sh: strip: not found (Solaris)</a></b></dt>
<dd>Install the SUNWbtool package.<br><br></dd>
<dt><b><a name="Build and install8">2.9. What is sh_tiger1.s?</a></b></dt>
<dd>This is a precompiled assembly file for the i386 architecture 
generated from sh_tiger1.c using gcc 3.4.0 with the following options,
that were found to generate the fastest code:
<pre>
 -O1 -fno-delayed-branch -fexpensive-optimizations -fstrength-reduce 
     -fpeephole2 -fschedule-insns2 -fregmove -frename-registers -fweb 
     -momit-leaf-frame-pointer -funroll-loops
</pre>
These options were determined using 
<a href="http://www.coyotegulch.com/products/acovea/">acovea</a> 5.1.1 
by  Scott Robert Ladd. The file is provided as precompiled assembly 
because different versions of gcc can have very different performance, 
require different options to compile optimal code, and
it would be impossible to maintain a library of optimal compile options
for every version of gcc.<br><br></dd>
<dt><b><a name="Build and install9">2.10. Why does static compiling (<code>--enable-static</code>) on MaxOS X fail ?</a></b></dt>
<dd>Static linking is not supported on MacOS X, see 
<a href="http://developer.apple.com/qa/qa2001/qa1118.html">Technical Q&A QA1118</a>. 
This is a MacOS X issue and not a bug in samhain.<br><br></dd>
<dt><b><a name="Build and install10">2.11. Why does compiling with MySQL fail on Solaris ?</a></b></dt>
<dd>The reason is often the shell script 'mysql_config' that comes as part
of MySQL. This script is intended to print appropriate compiler flags for
compiling applications that use MySQL. Unfortunately, since Sun compiles
MySQL with the Solaris compiler, this script outputs options for the Solaris 
compiler (i.e. unsuitable for gcc). To solve this problem, you need to move
this script (i.e. 'mysql_config') out of your PATH before running 
<tt>./configure</tt> (unless of course you are using the Solaris compiler
rather than gcc).<br><br></dd>
</dl>
<hr><h2>3. File checking</h2>
<dl>
<dt><b><a name="File checking0">3.1. How can I exclude a (sub-)directory ?</a></b></dt>
<dd><div class="block"><pre>
[IgnoreAll]
dir=-1/ignore/this/subdirectory
</pre></div><br><br></dd>
<dt><b><a name="File checking1">3.2. In messages about policy violations, what does the code after POLICY [XYZ] 
mean ?</a></b></dt>
<dd>This code indicates which items are modified (e.g. C = checksum). You can 
find a description in section 5.4.9 in the user manual. It is there because 
then you can see in the message list of the Beltane web console what has been 
modified, without the need to look at the message in detail.<br><br></dd>
<dt><b><a name="File checking2">3.3. Does samhain support prelink ?</a></b></dt>
<dd>Yes. There is a special checking policy [Prelink]. Directories with
prelinked executables / shared libraries (see /etc/prelink.conf) should be
placed under this policy, rather than under the [ReadOnly] policy.<br><br></dd>
<dt><b><a name="File checking3">3.4. I get error messages about 'subdirectory count != hardlinks'</a></b></dt>
<dd>Some filesystems do not always follow the rule that the number
of directory
hardlinks equals the number of subdirectories. E.g. the root directory of
reiserfs partitions generally seems to have two additional hardlinks.
To account for such exceptions, you can either switch off the
hardlink check globally, or specify exceptions:
<div class="block"><pre>
[Misc]
# Switch off hardlink check
#
UseHardlinkCheck=no
</pre></div>
<div class="block"><pre>
[Misc]
# Specify exceptions for the hardlink check
#
HardlinkOffset=N:/path
</pre></div>
Here, N is the numerical offset (actual - expected hardlinks) for 
'/path'. For multiple exceptions, use
this options multiple times (note that '/path N:/path2' would itself be a valid
path, so using the option only once with multiple exceptions on the same line 
would be ambiguous).<br><br></dd>
</dl>
<hr><h2>4. Client/Server</h2>
<dl>
<dt><b><a name="Client/Server0">4.1. I don't want to poke a hole into my firewall to let the client connect to the server !</a></b></dt>
<dd>Pat Smith has posted the following solution. On the client, create
an iptable rule as follows (<i>note: you probably don't need this if you
configure / compile in 127.0.0.1 as the server address</i>):
<div class="block"><pre>
iptables -t nat -A OUTPUT -p tcp -m tcp --dport 49777 -d <i>server-ip</i> -j REDIRECT
</pre></div>

On the server, create an ssh tunnel for each client outside the firewall:

<div class="block"><pre>
ssh -f -C -R 49777:localhost:49777 -N <i>client-ip</i>
</pre></div>

It is necessary that each client has a distinct name, and that the server
knows the name of the client. With the setup above, each client will appear
as &quot;localhost&quot; to the server, thus the server 
needs to trust the client name
as reported by the client itself, and suppress all errors on resolving
this name to the apparent address. In the server configuration:

<div class="block"><pre>
[Misc]
SetClientFromAccept = false
SeverityLookup = debug
</pre></div>

Obviously, self-resolving must work on the client machine, otherwise
you are in trouble (see next issue).<br><br></dd>
<dt><b><a name="Client/Server1">4.2. The client sends 127.0.0.1 (or some other numerical address) as its name to the log server</a></b></dt>
<dd>See 'Client cannot self-resolve' in the 'Most frequently' section<br><br></dd>
<dt><b><a name="Client/Server2">4.3. The server wants to send rc.ip-adress rather than rc.fqdn to the client</a></b></dt>
<dd>The client self-resolves to its ip address. 
See 'Client cannot self-resolve' in the 'Most frequently' section<br><br></dd>
<dt><b><a name="Client/Server3">4.4. Cannot resolve client name host=XXX</a></b></dt>
<dd><div class="block"><pre>
The server must be able to determine the client name.
This is because only authenticated connections from registered 
clients are allowed, and
the server must be able to check the client hostname against the list of
allowed hosts, and look up the password verifier for that
host.
</pre></div>
There are two different ways to accomplish this. Unfortunately, judging 
from customer feedback as well from common sense, both do not work very well
with a messed up local DNS (including /etc/hosts files) and/or
&uuml;berparanoid or misconfigured firewalls (in case of connections 
across one).
<ul>
  <li>
     <p>
     <i>First method: Determine client name on client, and 
     try to cross-check on server</i>
     <p>
     <p>
     This does not work for a number of people because (1) the
     <tt>/etc/hosts</tt> file on the client machine has errors 
     (yes, there are plenty machines with a completely 
     messed up <tt>/etc/hosts</tt> file), (2) the
     server cannot resolve the client address because the local DNS is
     f***ed up, or (3) the client machine has multiple network interfaces, and
     the interface used is not the one the client name resolves to.
     </p>
       <p>
       If the client uses the wrong interface on a multi-interface machine, 
       there is a config file option 
       <tt>SetBindAddress=</tt><i>IP address</i>
       that allows to choose the interface the client will use for
       outgoing connections.
       </p>
       <p>
       If you want to download the config file from the server, you
       should instead use the corresponding command line
       <tt>--bind-address=</tt><i>IP address</i>
       to select the interface.
       </p>

     <p>
     If you encounter problems, you may (1) fix your 
     <tt>/etc/hosts</tt> file(s), (2) fix your local DNS, or
     (3) switch to the second method.
     </p>
     <p>
     Errors in name resolving/cross-checking can be avoided by setting a 
     very low severity (lower than the logging threshold), e.g.
     </p>
     <p>
     <tt>SeverityLookup=</tt><i>debug</i>
     </p>
     <p>
     in the <i>Misc</i> section of the server configuration,
     if you prefer running <i>unsafe</i> at any speed 
     instead of fixing the problem (you have been warned). Doing so will
     allow an attacker to pose as the client.
     </p>
  </li>
  <li>
     <p><i>Second method: Use address of connecting entity as 
     known to the communication layer</i></p>
     <p>
     This has been dropped as default 
     long ago because it may not always be the 
     address of the client machine. 
     To enable this method, use
     </p>
     <p>
     <tt>SetClientFromAccept=</tt><i>true</i>
     </p>
     <p>
     in the <i>Misc</i> section of the server configuration
     file. If the address cannot be resolved, or reverse lookup of the
     resolved name fails, <i>no</i> error message will be issued,
     but the numerical address will be used.
     </p>
  </li>
</ul><br><br></dd>
<dt><b><a name="Client/Server4">4.5. Cannot resolve socket peer IP for client host=XXX peer=YYY</a></b></dt>
<dd>See above<br><br></dd>
<dt><b><a name="Client/Server5">4.6. Reverse lookup of socket peer failed host=XXX peer=YYY obj=ZZZ</a></b></dt>
<dd>See above<br><br></dd>
<dt><b><a name="Client/Server6">4.7. No socket peer alias matches client name host=XXX peer=YYY</a></b></dt>
<dd>See above<br><br></dd>
<dt><b><a name="Client/Server7">4.8. Session key negotiation failed</a></b></dt>
<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
<dt><b><a name="Client/Server8">4.9. Invalid connection attempt: Not in client list</a></b></dt>
<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
<dt><b><a name="Client/Server9">4.10. Invalid connection attempt: Session key mismatch</a></b></dt>
<dd>See the document <a href="HOWTO-client+server-troubleshooting.html">HOWTO client+server troubleshooting</a><br><br></dd>
<dt><b><a name="Client/Server10">4.11. How do I update the file signature database ?</a></b></dt>
<dd>If you keep the file signature database on the server,
     the database is supposed to be updated on the server, using the
     <a href="http://www.la-samhna.de/beltane/">beltane</a> 
     web-based console (currently in beta) and the
     log messages from the client.
     <p>
     Alternatively, you can <code>scp</code> the database
     to the client, run <code>samhain -t update -l none --foreground</code> 
     (you
     need to avoid logging because otherwise you will get in conflict with
     the running samhain daemon), and then <code>scp</code> the 
     database back to the server. Actually, with a properly set up 
     &quot;ssh&quot;, using RSA/DSA authentication 
     and ssh-agent you could write a script to automate this.<br><br></dd>
<dt><b><a name="Client/Server11">4.12. Time limit exceeded</a></b></dt>
<dd>The respective client for that this message is generated has not
        sent anything for some interval of time (default 84600 sec = 1 day).
        The interval can be set as follows:
<div class="block"><pre>
        [Misc]
	# unit is seconds
        SetClientTimeLimit=NNN
</pre></div>

        This feature has the purpose to detect if a client is dead. You
        might want to ensure that timestamps are sent to the server:
<div class="block"><pre>
        [Log]
	ExportSeverity=mark
</pre></div>
        If you don't want to use this feature, set the time limit to some
        very large value.<br><br></dd>
<dt><b><a name="Client/Server12">4.13. Invalid connection attempt:  Signature mismatch</a></b></dt>
<dd>Clients sign their messages using a session key negotiated
        with the server. The message indicates that the server could
        not verify the signature. This may be caused by a running two
        instances of samhain on the same client machine, both of them
        accessing the server (and negotiating different session keys
        ...). The system will recover automatically from the problem
        by forcing the failed client to negotiate a fresh session key.<br><br></dd>
<dt><b><a name="Client/Server13">4.14. [Server] PANIC .. Address already in use&nbsp; &nbsp;subroutine=bind</a></b></dt>
<dd>The server cannot bind to its port because the port is already used.
        Maybe you have accidentially already an instance of the
        server running.<br><br></dd>
</dl>
<hr><h2>5. Email</h2>
<dl>
<dt><b><a name="Email0">5.1. Reverse lookup failed</a></b></dt>
<dd>Fix your DNS (reverse lookup: numerical IP address to FQDN, to verify 
   FQDN to numerical IP address).
<div class="block"><pre>
Whether &quot;nslookup&quot; works is not very informative, because 
&quot;nslookup&quot; does not use the resolver library of the operating
system. Therefore,
it is not exactly the
best tool for debugging name resolving problems (see the book
&quot;DNS and bind&quot;).
</pre></div><br><br></dd>
<dt><b><a name="Email1">5.2. From daemon@example.com</a></b></dt>
<dd>samhain fails to resolve the
        self-address of the host. 
See 'Client cannot self-resolve' in the 'Most frequently' section.<br><br></dd>
<dt><b><a name="Email2">5.3. How do I define more than one email addresses ?</a></b></dt>
<dd>Use <tt>SetMailAddress=...</tt> multiple times (upt to eight addresses
are possible, with at most 63 characters per address):
<div class="block"><pre>
[Misc]
SetMailAddress=aaa@foo.com
SetMailAddress=bbb@foo.com
</pre></div><br><br></dd>
</dl>
<hr><h2>6. Misc</h2>
<dl>
<dt><b><a name="Misc0">6.1. Error message: &quot;Invalid line XYZ in configuration file&quot;</a></b></dt>
<dd>This message indicates that line XYZ in the configuration file contains
an unrecognized directive. The primary reasons are:<br />

(a) The directive should be placed into a particular section of the
configuration file, but the section header is not present (or you forgot
to uncomment it).<br />

(b) Samhain is compiled without support for this directive.<br />

(c) You have a typo in the directive.<br /><br><br></dd>
<dt><b><a name="Misc1">6.2. Why do I get a local logfile if I log to the server ?</a></b></dt>
<dd>Because you can use all log facilities in parallel. You should
        switch off in the config file what you don't want/need:
<div class="block"><pre>
        [Log]
        # local log file
        LogSeverity=none
</pre></div><br><br></dd>
<dt><b><a name="Misc2">6.3. Why is there no NIS support with a static samhain executable on Linux ?</a></b></dt>
<dd>Some functions (including NIS) require 
   libraries that are only available as shared libraries
   with modern GLIBC versions. While you can always compile a static
   executable, normally it would still open the shared library at runtime.
   As of version 1.8.11, samhain avoids this by providing replacement
   functions from uClibc. However, these do not include NIS support.<br><br></dd>
<dt><b><a name="Misc3">6.4. Why do I get hundreds of messages about modified CTIME ?</a></b></dt>
<dd>This happens because some
        backup applications reset the atime/mtime timestamps, which causes
        the ctime timestamp to be modified (rootkits avoid this by
        temporarily resetting the system clock to the original ctime ...).
	<p>
        To fix this problem, read the manual of your backup application, or 
        redefine the ReadOnly policy to <i>not</i> check
        the ctime timestamp:
<div class="block"><pre>
        [Misc]
        RedefReadOnly=-CTM
</pre></div>
<div class="warnblock"><pre>
        Order matters - you must <i>first</i> redefine 
        ReadOnly <i>before</i> you use it
</pre></div><br><br></dd>
<dt><b><a name="Misc4">6.5. PANIC &mdash; File not accessible</a></b></dt>
<dd>Most likely permission denied because of unsufficient privileges.<br><br></dd>
<dt><b><a name="Misc5">6.6. How can I avoid error messages for invalid UIDs (no such user) ?</a></b></dt>
<dd>Set SeverityNames to a low value
<div class="block"><pre>
[EventSeverity]
SeverityNames=debug
</pre></div><br><br></dd>
<dt><b><a name="Misc6">6.7. [Redhat] The /etc/init.d/(samhain|yule) init script hangs</a></b></dt>
<dd>Redhat uses &quot;initlog&quot; (see 
     <code>man initlog</code>) in initscripts. If it hangs, most probably
     samhain/yule runs in the foreground rather than as daemon. Set
     daemon mode in the configuration file:
<div class="block"><pre>
[Misc]
Daemon=yes
</pre></div><br><br></dd>
<dt><b><a name="Misc7">6.8. The /etc/init.d/(samhain|yule) init script exits with: execvp: No such file or directory</a></b></dt>
<dd>Either the program is not installed, or it is not in the PATH (the one
     used by the init script, which may be different from your PATH).<br><br></dd>
<dt><b><a name="Misc8">6.9. Why am I not receiving the &quot;BEGIN LOGKEY&quot; message by email ?</a></b></dt>
<dd>This message (which contains the key to verify the log file) is generated
   when logging to the log file starts. It has the severity &quot;ALRT&quot;,
   thus you should make sure that you have set the logging threshold for
   email correctly to receive it.<br><br></dd>
<dt><b><a name="Misc9">6.10. Why does console logging fail if I compile with 
   <code>--enable-(micro-)stealth</code> ?</a></b></dt>
<dd>The default logging options are more &quot;stealthy&quot;. Set the
   threshold explicitely rather than relying on the default.<br><br></dd>
<dt><b><a name="Misc10">6.11. I need a list for my schedule !</a></b></dt>
<dd>You can have the same effect with a list of schedules. See the section
&quot;Timing file checks&quot; in the manual.<br><br></dd>
<dt><b><a name="Misc11">6.12. The hiding kernel module has no effect !</a></b></dt>
<dd>Most probably you compiled using the wrong &quot;System.map&quot; file.<br><br></dd>
<dt><b><a name="Misc12">6.13. What does the message &quot;Large lstat/open overhead&quot; mean ?</a></b></dt>
<dd>Your system needs several seconds to proceed from an lstat() system call
   to an open() system call. This is a tremenduous overhead, and 
   indicates that either your system has a really severe performance problem,
   or someone tries to slow down samhain.<br><br></dd>
<dt><b><a name="Misc13">6.14. What does the message &quot;Device not available path=/dev/random&quot; mean ? I have /dev/random !</a></b></dt>
<dd>/dev/random blocks unless there is some entropy it can deliver. Samhain 
   will time out and fall back on /dev/urandom after some seconds to avoid 
   hanging for a potentially long time. It will try /dev/random again next 
   time it needs entropy.<br><br></dd>
<dt><b><a name="Misc14">6.15. Logging to an external program fails; the program receives no data 
   on stdin !</a></b></dt>
<dd>Probably your program is not designed to <i>wait for input</i>, but exits
   if reading fails (because there is no data <i>yet</i>). You may want to 
   let your program wait for the terminating &quot;[EOF]&quot; line.<br><br></dd>
<dt><b><a name="Misc15">6.16. SIGILL on AIX</a></b></dt>
<dd>For each scanned file, samhain needs to 
     store some information in memory (e.g. to recognize changes that have
     already been reported, and avoid duplicate reports). On AIX, if you are
     checking a <i>really huge</i> number of files, 
     memory usage may exceed the default limit of 256 MB, and the process may 
     terminate with SIGILL.
     <p>
     The problem can be solved by linking with the flag 
     <code>-bmaxdata:0x80000000</code>. This allows the application to
     access up to 8 segments (where each segment is 256MB).
     <p>
     If you are using gcc, you need to use instead
     the flag <code>-Wl,bmaxdata:0x80000000</code>, which tells 
     gcc to pass on the 
     <i>bmaxdata</i>
     flag to the AIX linker. You can use the LDFLAGS environment variable to
     pass linker flags to the configure script:
<div class="block"><pre>
     export LDFLAGS="-Wl,bmaxdata:0x80000000"
</pre></div><br><br></dd>
</dl>
<hr><h2>7. Database</h2>
<dl>
<dt><b><a name="Database0">7.1. Why are client messages corrupted / incompletely stored in the DB ?</a></b></dt>
<dd>Because the messages are not in XML format, and therefore incorrectly
        parsed. The most frequent reasons are:
<div class="block"><pre>
        1.) Your server is compiled with --enable-xml-log, but your client(s)
        is/are not.

        2.) In your client or server configuration file, you are using
        the option for a custom message header, but without paying attention
        to preserving the XML format.
</pre></div><br><br></dd>
<dt><b><a name="Database1">7.2. I want / don't want the server timestamps (for client messages) in the SQL database</a></b></dt>
<dd><div class="block"><pre>
[Database]
SetDBServerTstamp = true/false
</pre></div>

     This will enable/disable logging of the server timestamp for client
     messages. The server timestamp will be written to a seperate record,
     with <i>log_ref</i> set to the value of 
     <i>log_index</i> of the corresponding client message.<br><br></dd>
<dt><b><a name="Database2">7.3. I don't want the client TIMESTAMP messages in the SQL database</a></b></dt>
<dd><div class="block"><pre>
     Sending timestamps from the client allows the server to detect if
     a client is not running anymore (use SetClientTimeLimit=NNN in the
     [Misc] section of the server config file to set the number of seconds
     after which the server will issue an error message if no timestamp has
     been received).
</pre></div>

     However, you might not want to log these timestamps to the database
     (or other log facilities). To filter them, you can use two methods
     (examples are for the SQL database). 
     The first
     one has the disadvantage that only messages of 
     severity <i>err</i> or higher will be logged:
<div class="block"><pre>
     [Misc]
     UseClientSeverity=yes

     [Log]
     DatabaseSeverity=err
</pre></div>

     The second method is more specific &mdash; log everything not
     belonging to the STAMP class of messages:
<div class="block"><pre>
     [Misc]
     UseClientClass=yes

     [Log]
     DatabaseClass=PANIC RUN FIL TCP ERR ENET EINPUT
</pre></div><br><br></dd>
<dt><b><a name="Database3">7.4. What does the log_ref field mean ?</a></b></dt>
<dd>NULL are client messages. Nonzero integer is a server timestamp
        for a client message (where log_ref indicates the log_index entry 
        number of the corresponding client message). Zero indicates a message
        by the server itself (e.g. the server's start message).<br><br></dd>
<dt><b><a name="Database4">7.5. How can I check what is in the database ?</a></b></dt>
<dd>Use a command line client to login to the database and query it:
<div class="block"><pre>
     sh$ mysql -u &lt;user_name&gt; -p &lt;database_name&gt;
     Enter password: ****
     mysql&gt; SELECT log_index,log_ref,log_host,log_sev,log_msg,path FROM &lt;table_name&gt; WHERE entry_status = 'NEW' ORDER BY log_index;
     ....
     mysql&gt; \q 
</pre></div><br><br></dd>
</dl>
<hr>

<p>Copyright (c) 2004 Rainer Wichmann</p>

<p><i>This list of questions  and answers was generated by 
<a href="http://www.makefaq.org/">makefaq</a>.</i>

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samhain 3.1.0-5ubuntu1 / usr / share / doc / samhain / FAQ.html
