Changing TCP MSS for IPv6

Changing TCP MSS for IPv6

[Dimitrios Pezaros]

Dear all,

I am experimenting with altering the TCP MSS using iptables/ip6tables
v1.2.5 under Linux 2.4.18

I am able to do that for IPv4 traffic using the options e.g.
iptables -A OUTPUT -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss
1000
iptables -A OUTPUT -p tcp --tcp-flags SYN,RST SYN -j TCPMSS
--clamp-mss-to-pmtu

This is, as expected, applied to IPv4 traffic. I need to do something
equivalent (being able to manually alter MSS) for IPv6, but the TCPMSS
option does not seem to work for ip6tables.

------------------------------------------------------------------------
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# ip6tables -A OUTPUT -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss
1400
ip6tables v1.2.5: Unknown arg `--set-mss'
Try `ip6tables -h' or 'ip6tables --help' for more information.
------------------------------------------------------------------------
-----

Am I doing something obviously wrong, or such functionality is not (yet)
implemented for ip6tables?
Or even, is there a specific patch that I need to apply?

Many thanks for any help,
Dimitris.