diff options
| author | Henrik Nordstrom <hno@marasystems.com> | 2004-01-22 15:04:24 +0000 |
|---|---|---|
| committer | Harald Welte <laforge@gnumonks.org> | 2004-01-22 15:04:24 +0000 |
| commit | c2794131b445ebccba184066af6d3fb2f38d1f38 (patch) | |
| tree | a24f57a9be5a8364b53dfa102705d270f36b440a /extensions/libipt_TCPMSS.man | |
| parent | 0113fe75ff05e09e6f3d251534d9ae32e9aa717c (diff) | |
split manpages into per-extension manpage snippet (Henrik Nordstrom)
add lots of missing manpage snippets (Harald Welte)
Diffstat (limited to 'extensions/libipt_TCPMSS.man')
| -rw-r--r-- | extensions/libipt_TCPMSS.man | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/extensions/libipt_TCPMSS.man b/extensions/libipt_TCPMSS.man new file mode 100644 index 00000000..da1bce2d --- /dev/null +++ b/extensions/libipt_TCPMSS.man @@ -0,0 +1,38 @@ +This target allows to alter the MSS value of TCP SYN packets, to control +the maximum size for that connection (usually limiting it to your +outgoing interface's MTU minus 40). Of course, it can only be used +in conjunction with +.BR "-p tcp" . +.br +This target is used to overcome criminally braindead ISPs or servers +which block ICMP Fragmentation Needed packets. The symptoms of this +problem are that everything works fine from your Linux +firewall/router, but machines behind it can never exchange large +packets: +.PD 0 +.RS 0.1i +.TP 0.3i +1) +Web browsers connect, then hang with no data received. +.TP +2) +Small mail works fine, but large emails hang. +.TP +3) +ssh works fine, but scp hangs after initial handshaking. +.RE +.PD +Workaround: activate this option and add a rule to your firewall +configuration like: +.nf + iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN \\ + -j TCPMSS --clamp-mss-to-pmtu +.fi +.TP +.BI "--set-mss " "value" +Explicitly set MSS option to specified value. +.TP +.B "--clamp-mss-to-pmtu" +Automatically clamp MSS value to (path_MTU - 40). +.TP +These options are mutually exclusive. |