1 This target allows to alter the MSS value of TCP SYN packets, to control
2 the maximum size for that connection (usually limiting it to your
3 outgoing interface's MTU minus 60). Of course, it can only be used
6 It is only valid in the
10 This target is used to overcome criminally braindead ISPs or servers
11 which block ICMPv6 Packet Too Big packets or are unable to send them.
12 The symptoms of this problem are that everything works fine from your
13 Linux firewall/router, but machines behind it can never exchange large
19 Web browsers connect, then hang with no data received.
22 Small mail works fine, but large emails hang.
25 ssh works fine, but scp hangs after initial handshaking.
28 Workaround: activate this option and add a rule to your firewall
31 ip6tables -t mangle -A FORWARD -p tcp --tcp-flags SYN,RST SYN \\
32 -j TCPMSS --clamp-mss-to-pmtu
35 .BI "--set-mss " "value"
36 Explicitly set MSS option to specified value.
38 .B "--clamp-mss-to-pmtu"
39 Automatically clamp MSS value to (path_MTU - 60).
41 These options are mutually exclusive.