[strongSwan] ifconfig eth0 mtu 1400 < 1500

Markus Wildi wildi.markus at bluewin.ch
Tue Jul 24 17:07:33 CEST 2012

Hello all

at first I'd like to thank the developers of StrongSWAN
not only for the comprehensible configuration!

I observed in case eth0 ( on system vermes 
has a MTU of 1500 that the traffic sent by StrongSWAN 
gets stuck with no traces in the log file. This happens
only if I copy a file or issue a ls -lR / .

The ordinary traffic over eth0 is not affected. The actual, 
e.g. ssh connection, does not recover. After opening a new 
one over StrongSWAN I can type on the cmd line or edit a file. 

If I change the MTU to e.g. 1400 then traffic flows freely.

I observed that on an recent OpenSuSE and on a Debian 
squeeze both being i586 alix systems (PCengine).

Any idea?

bye, wildi

Network setup ("double road warrior"):

Internet:   obsbasel.dyndns.org       obsvermes.org
                   |                  |  
home--------fritzbox --- Internet --- SwisscomGrande ---vermes
   |        |                                      |    |
   |            |
eth0:                                       eth0:

Linux obsvermes 3.1.10-1.16-default #1 SMP Wed Jun 27 05:21:40 UTC 2012 
(d016078) i586 i586 i386 GNU/Linux

Repository: @System
Name: strongswan
Version: 4.5.3-5.4.1
Arch: i586
Vendor: openSUSE

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