Author: Marc Boucher
Status: Included in kernel 2.4.4

This patch adds the CONFIG_IP_NF_TARGET_TCPMSS and
CONFIG_IP_NF_MATCH_TCPMSS options, which allow you to examine and
alter the MSS value of TCP SYN packets, to control the maximum size
for that connection.  THIS IS A HACK, used to overcome criminally
braindead ISPs or servers which block ICMP Fragmentation Needed
packets.

Typical usage:

iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu

