So maybe the following patch is necessary... I believe IPV6 & DCCP are immune to this problem. Thanks again Denys for spotting this. Eric [PATCH] TCP : secure_tcp_sequence_number() should not use a too fast clock TCP V4 sequence numbers are 32bits, and RFC 793 assumed a 250 KHz clock. In order to follow network speed increase, we can use a faster clock, but we should limit this clock so that the delay between two rollovers is greater than MSL (TCP Maximum Segment Lifetime : 2 minutes) Choosing a 64 nsec clock should be OK, since the rollovers occur every 274 seconds. Problem spotted by Denys Fedoryshchenko Signed-off-by: Eric Dumazet