Timing related problem with nmap > 3.20?

[Richard Moore <rich () westpoint ltd uk>]

Hi all,

I recently upgraded to nmap 3.27 and I seem to be hitting a problem - I 
get the message:

Serious time computation problem in adjust_timeout ... received = 
(1054717924, 348069) sent=(1054717924,350690) delta = 0 srtt = -2621 
rttvar = 5000 to = 300000
QUITTING!

when I run nmap as root (it is fine when run as a non-root user). If I 
try using nmap 3.20 the same scan works fine. I'm using RH 7.2, and 
given that things are ok as non-root I suspect the problem is related to 
the following change:

o Packet receive times are now obtained from libpcap rather than
  simply using the time the packets are passed to Nmap.  This should
  improve performance slightly.  I was not able to get this to work
  properly on Windows (either pcap or raw) -- join the nmap-dev list
  if you have ideas.

The time difference between the machine running the scan and the target 
is very small as the hosts both sync to the same NTP server every half 
an hour (even syncing the clock immediately before the scan doesn't seem 
to help).

I've checked Redhat's site and I don't see any updates available, so I 
was wondering if anyone else is seeing the problem?

Cheers

Rich.


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