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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I have been searching all over the internet for a solution
to the common “kernel: dst cache overflow” problem people have been
having… Here’s my synopsis, I am running 14 Linux firewalls, 9 on
Fedora core 2, 1 on Fedora core 1 and 3 on Red Hat 9. All of the firewalls have
about 3-4 Copper Gig NICs, on Dell PowerEdge 700 with 512mb memory and a P4
2.8Ghz CPU. The firewalls have just above bare minimal pkgs installs, all
installed from a kickstart file and all services (if any un-used) have been
turn off and disable in the runlevels. These are only firewalls for internet
and private traffic across T1’s and higher. All fedora core 2 firewalls
have and running the latest kernel 2.6.9-1.6_FC2smp, but each kernel before
that also had the errors, so there are no fixes in the kernel. All Red Hat
firewalls are running 2.4.25 kernel and the 1 fedora core 1 is running 2.4.26,
but none of them are experiencing this issue.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>On the Fedora Core 2 firewalls, I get the below kernel
messages after a certain amount of traffic, what that amount is, I do not know.
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>kernel: dst cache overflow<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>kernel: printk: 52 messages suppressed.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>kernel: dst cache overflow<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>kernel: printk: 36 messages suppressed.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>kernel: dst cache overflow <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>After so much traffic or time, the firewall becomes
unresponsive on the network and I may or may not get this new message, and the
system needs a hard reboot.<br>
<br>
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>syslogd: sendto: No buffer space available<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>kernel: dst cache overflow<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>last message repeated 5 times<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>last message repeated 9 times<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>last message repeated 3 times<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>syslogd: sendto: No buffer space available<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>kernel: dst cache overflow<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>last message repeated 3 times<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>last message repeated 3 times<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I have tried just resetting the network ( service network
restart), I also tried just to stop the network for a few hours, I tried the
recommendation of setting the route max_size in
/proc/sys/net/ipv4/route/max_size (<a
href="http://seclists.org/lists/vulnwatch/2003/Apr-Jun/0076.html">http://seclists.org/lists/vulnwatch/2003/Apr-Jun/0076.html</a>),
none seemed to help. I am now trying a custom 2.4.28 kernel on one of the
firewalls to see if that may help. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Has anyone run into this and fixed it? It seems to be only
with Fedora Core 2, I am curious if Fedora 3 would make a difference, but I am
not ready to leap into that bird nest just yet.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Thanks,</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Michael Brown</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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