This iptables module changes TCP window header field. The purpose is only testing and debugging because of changing TCP window usualy is very bad idea. Repository contains both iptables module for kernel and iptables plug-in for userspace. It is based on TTL module written by Harald Welte <laforge@netfilter.org> Usage example: - make modules and put them to proper places - modprobe xt_TCPBODY - iptables -t mangle -I OUTPUT -p tcp --sport 80 --tcp-flags SYN,ACK SYN,ACK -j TCPBODY --tcpwin-set 0