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Diffstat (limited to 'docs/firewall.rst')
| -rw-r--r-- | docs/firewall.rst | 37 |
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diff --git a/docs/firewall.rst b/docs/firewall.rst index 8ab4dacf..e14cb19b 100644 --- a/docs/firewall.rst +++ b/docs/firewall.rst @@ -174,5 +174,42 @@ Example Partial Config } } +MSS Clamping +------------ + +As Internet wide PMTU discovery rarely works we sometimes need to clamp our TCP +MSS value to a specific value. Starting with VyOS 1.2 there is a firewall option +to clamp your TCP MSS value for IPv4 and IPv6. + +Clamping can be disabled per interface using the `disable` keywork: + +.. code-block:: sh + + set firewall options interface pppoe0 disable + +IPv4 +---- + +Clamp outgoing MSS value in a TCP SYN packet to `1452` for `pppoe0` and `1372` +for your WireGuard `wg02` tunnel. + +.. code-block:: sh + + set firewall options interface pppoe0 adjust-mss '1452' + set firewall options interface wg02 adjust-mss '1372' + +IPv6 +---- + +Clamp outgoing MSS value in a TCP SYN packet to `1280` for both `pppoe0` and +`wg02` interface. + +To achieve the same for IPv6 please use: + +.. code-block:: sh + + set firewall options interface pppoe0 adjust-mss6 '1280' + set firewall options interface wg02 adjust-mss6 '1280' + [https://www.xfinity.com/support/internet/list-of-blocked-ports/ XFinity Blocked Port List] |