kern/102344: Some packets do not pass through network interface

Alexander Shkurko read at
Mon Aug 21 12:50:16 UTC 2006

>Number:         102344
>Category:       kern
>Synopsis:       Some packets do not pass through network interface
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Aug 21 12:50:14 GMT 2006
>Originator:     Alexander Shkurko
>Release:        FreeBSD 6.1
testfree# uname -a
testfree# uname -a
FreeBSD 6.1-RELEASE FreeBSD 6.1-RELEASE #0: Mon Aug 21 15:11:29 EEST 2006     andrew at  i386
Packets of some size do not pass through network interface.

After some experiment's i found size of ICMP packet's that do not pass.
  Size of payload, range 
  1473 bytes - 1479 bytes
  2953 bytes - 2959 bytes
  4433 bytes - 4439 bytes
  5913 bytes - 5919 bytes

So, we have formula of size of problem payloads:
1473+x*1480  - 1479+x*1480, where x=1,2,3,4,5,6...

I have kernel:

testfree# diff -u /usr/src/sys/i386/conf/GENERIC /usr/src/sys/i386/conf/black
--- /usr/src/sys/i386/conf/GENERIC      Mon May  1 03:15:12 2006
+++ /usr/src/sys/i386/conf/black        Mon Aug 21 14:52:37 2006
@@ -279,3 +279,6 @@
 device         firewire        # FireWire bus code
 device         sbp             # SCSI over FireWire (Requires scbus and da)
 device         fwe             # Ethernet over FireWire (non-standard!)
+options         IPFILTER

Add to "generic" kernel support of IPFILTER,install this kernel,reboot, and ping any IP address with payload of 1475 bytes:
ping -s 1475 any_ip_address

Disable support of IPFILTER and problem disappear.

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