On Tue, Jun 18, 2019 at 1:40 PM Florian Westphal <fw@xxxxxxxxx> wrote: > > Problem is that we do not keep any state. Syncookes are restricted to 4 > mss value: > static __u16 const msstab[] = { > 536, > 1300, > 1440, /* 1440, 1452: PPPoE */ > 1460, > }; > > So, 1260 forces lowest value supported. > > The table was based off a research paper that had mss distribution > tables. Maybe more recent data is available and if things have changed > we could update the table accordingly. I am confused. So this statement from manual page is just a illusion? --mss maximum segment size Maximum segment size announced to clients. This must match the backend. I don't understand why these restriction exist. Why can't we set mss value same as what client send to us?