Re: [PATCH v2 net] tcp: randomize timestamps on syncookies

2017-05-05 Thread Eric Dumazet
On Fri, 2017-05-05 at 11:36 +0200, Florian Westphal wrote: > Eric Dumazet wrote: > > From: Eric Dumazet > > > > Whole point of randomization was to hide server uptime, but an attacker > > can simply start a syn flood and TCP generates 'old style' timestamps, > > directly revealing server jiffies

Re: [PATCH v2 net] tcp: randomize timestamps on syncookies

2017-05-05 Thread Florian Westphal
Eric Dumazet wrote: > From: Eric Dumazet > > Whole point of randomization was to hide server uptime, but an attacker > can simply start a syn flood and TCP generates 'old style' timestamps, > directly revealing server jiffies value. > > Also, TSval sent by the server to a particular remote addr

[PATCH v2 net] tcp: randomize timestamps on syncookies

2017-05-04 Thread Eric Dumazet
From: Eric Dumazet Whole point of randomization was to hide server uptime, but an attacker can simply start a syn flood and TCP generates 'old style' timestamps, directly revealing server jiffies value. Also, TSval sent by the server to a particular remote address vary depending on syncookies be