]> git.karo-electronics.de Git - linux-beck.git/commit
tcp: allow timestamps even if SYN packet has tsval=0
authorEric Dumazet <dada1@cosmosbay.com>
Wed, 11 Mar 2009 16:23:57 +0000 (09:23 -0700)
committerDavid S. Miller <davem@davemloft.net>
Wed, 11 Mar 2009 16:23:57 +0000 (09:23 -0700)
commitfc1ad92dfc4e363a055053746552cdb445ba5c57
tree6f6f8ef6cd887530f5eb4d083cbaceaa8f0512c8
parent3e1a3ce2f19a8a74fe6771f6dcd642d61ae050dc
tcp: allow timestamps even if SYN packet has tsval=0

Some systems send SYN packets with apparently wrong RFC1323 timestamp
option values [timestamp tsval=0 tsecr=0].
It might be for security reasons (http://www.secuobs.com/plugs/25220.shtml )

Linux TCP stack ignores this option and sends back a SYN+ACK packet
without timestamp option, thus many TCP flows cannot use timestamps
and lose some benefit of RFC1323.

Other operating systems seem to not care about initial tsval value, and let
tcp flows to negotiate timestamp option.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv4/tcp_ipv4.c