On 2010/12/17 23:18, Karl O. Pinc wrote: > Hi, > > I'm wondering why pf.conf(5) has an example > scrub setting where the mtu is 1440 when > 1460 would be the usual mtu for a 1500 > byte IP datagram. > > From OpenBSD 4.8: > -----------<snip>---------- > For example: > > match in all scrub (no-df max-mss 1440) > -----------<snip>---------- > > Is my brain just not clicking?
The normal use case for max-mss is when packets are forwarded via a tunnel of some sort (pppoe, gif, gre, ipsec etc) where full-sized packets can't be passed through. So you would usually want to set it to a lower value than is already in the packet.
