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<LI><A NAME="tex2html196"
  HREF="node5.html#SECTION00051000000000000000"><SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">1</SPAN> Can't open eth0: libnet_select_device(): Can't find interface eth0</A>
<LI><A NAME="tex2html197"
  HREF="node5.html#SECTION00052000000000000000"><SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">2</SPAN> Can't open lo: libnet_select_device(): Can't find interface lo</A>
<LI><A NAME="tex2html198"
  HREF="node5.html#SECTION00053000000000000000"><SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">3</SPAN> Can't open eth0: UID != 0</A>
<LI><A NAME="tex2html199"
  HREF="node5.html#SECTION00054000000000000000"><SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">4</SPAN> 100000 write attempts failed from full buffers and were repeated</A>
<LI><A NAME="tex2html200"
  HREF="node5.html#SECTION00055000000000000000"><SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">5</SPAN> Unable to process test.cache: cache file version missmatch</A>
<LI><A NAME="tex2html201"
  HREF="node5.html#SECTION00056000000000000000"><SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">6</SPAN> Skipping SLL loopback packet.</A>
<LI><A NAME="tex2html202"
  HREF="node5.html#SECTION00057000000000000000"><SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">7</SPAN> Packet length (8892) is greater then MTU; skipping packet.</A>
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<H1><A NAME="SECTION00050000000000000000">
<SPAN CLASS="arabic">4</SPAN> Common Error and Warning Messages</A>
</H1>

<P>

<H2><A NAME="SECTION00051000000000000000">
<SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">1</SPAN> Can't open eth0: libnet_select_device(): Can't find interface eth0</A>
</H2>

<P>
Generally this occurs when the interface (eth0 in this example) is
not up or doesn't have an IP address assigned to it. 

<P>

<H2><A NAME="SECTION00052000000000000000">
<SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">2</SPAN> Can't open lo: libnet_select_device(): Can't find interface lo</A>
</H2>

<P>
Version 1.1.0 of Libnet is unable to send traffic on the loopback
device. Upgrade to a later release of the Libnet library to solve
this problem.

<P>

<H2><A NAME="SECTION00053000000000000000">
<SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">3</SPAN> Can't open eth0: UID != 0</A>
</H2>

<P>
Tcpreplay requires that you run it as root.

<P>

<H2><A NAME="SECTION00054000000000000000">
<SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">4</SPAN> 100000 write attempts failed from full buffers and were repeated</A>
</H2>

<P>
When tcpreplay displays a message like &#34;100000 write attempts
failed from full buffers and were repeated&#34;, this usually
means the kernel buffers were full and it had to wait until memory
was available. This is quite common when replaying files as fast as
possible with the &#34;-R&#34; option. See the tuning OS
section in this document for suggestions on solving this problem.

<P>

<H2><A NAME="SECTION00055000000000000000">
<SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">5</SPAN> Unable to process test.cache: cache file version missmatch</A>
</H2>

<P>
Cache files generated by tcpprep and read by tcpreplay are versioned
to allow enhancements to the cache file format. Anytime the cache
file format changes, the version is incremented. Since this occurs
on a very rare basis, this is generally not an issue; however anytime
there is a change, it breaks compatibility with previously created
cache files. The solution for this problem is to use the same version
of tcpreplay and tcpprep to read/write the cache files. Cache file
versions match the following versions of tcpprep/tcpreplay:

<P>

<UL>
<LI>Version 1:
<BR>
Prior to 1.3.beta1
</LI>
<LI>Version 2:
<BR>
1.3.beta2 to 1.3.1/1.4.beta1
</LI>
<LI>Version 3:
<BR>
1.3.2/1.4.beta2 to 2.0.3
</LI>
<LI>Version 4:
<BR>
2.1.0 and above. Note that prior to version 2.3.0, tcpprep had a bug
which broke cache file compatibility between big and little endian
systems.
</LI>
</UL>

<P>

<H2><A NAME="SECTION00056000000000000000">
<SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">6</SPAN> Skipping SLL loopback packet.</A>
</H2>

<P>
Your capture file was created on Linux with the 'any' parameter which
then captured a packet on the loopback interface. However, tcpreplay
doesn't have enough information to actual send the packet, so it skips
it. Specifying a destination and source MAC address (-D and -S) will
allow tcpreplay to send these packets.

<P>

<H2><A NAME="SECTION00057000000000000000">
<SPAN CLASS="arabic">4</SPAN>.<SPAN CLASS="arabic">7</SPAN> Packet length (8892) is greater then MTU; skipping packet.</A>
</H2>

<P>
The packet length (in this case 8892 bytes) is greater then the maximum
transmition unit (MTU) on the outgoing interface. Tcpreplay must skip
the packet. Alternatively, you can specify the -T option and tcpreplay
will truncate the packet to the MTU size, fix the checksums and send
it. This often occurs with pcaps captured over loopback interfaces
which have much larger MTU's then ethernet.

<P>

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<ADDRESS>
Aaron Turner
2006-07-17
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