.. cfgcmd:: set interfaces {{ var0 }} <interface> {{ var2 }} {{ var3 }}
  {{ var5 }} {{ var6 }} adjust-mss <mss>

  As Internet wide PMTU discovery rarely works, we sometimes need to clamp our
  TCP MSS value to a specific value. This is a field in the TCP options part of
  a SYN packet. By setting the MSS value, you are telling the remote side
  unequivocally 'do not try to send me packets bigger than this value'.

  .. note:: This command was introduced in VyOS 1.4 - it was previously called:
    ``set firewall options interface <name> adjust-mss <value>``

  .. hint:: MSS value = MTU - 20 (IP header) - 20 (TCP header), resulting in
    1452 bytes on a 1492 byte MTU.