Why do we advertise 512 as the default MSS if the peer has no MSS  
instead of 536 ?
The code has a comment:

  /*
   * Default maximum segment size for TCP.
   * With an IP MSS of 576, this is 536,
   * but 512 is probably more convenient.
   */

Besides the fact that 512 is a power of 2, why do we use it?
This code seems to go back to 4.4-Lite so I'm not sure how to get the  
rcs/sccs log from that.

FYI, this related to http://www.netbsd.org/cgi-bin/query-pr-single.pl? 
number=14806

--
Rui Paulo