:FORWARD,OUTPUT,POSTROUTING *mangle -j TCPMSS;;FAIL -p tcp -j TCPMSS --set-mss 42;;FAIL -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -j TCPMSS --set-mss 42;=;OK -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -j TCPMSS --clamp-mss-to-pmtu;=;OK