Bug#503699: tcp mtu negotiation issue in 2.6.18-6-amd64
When configuring the network interface as mtu 9000, tcp mtu negotiation
is not working correctly. When the debian server initiates a tcp
connection and the other side tells it can only use mtu 1500, it is
ignored and still uses its own mtu 9000 when sending packets. If the
other side (which is using mtu 1500) initiates the connection, then the
debian server drops down to 1500 and things are fine.
I updated to testing's kernel linux-image-2.6.26-1-amd64 which has
resolved this issue and is working correctly.