Nmap Development: UDP scan bug in 3.81?

[Marcus <mcwimp () gmail com>]

I seem to have run into a bug in the nmap UDP scan code.
Are there any known problems/bugs in the UDP scan code of 
3.81? I checked the archives but didn't find anything.


Here are some details on the problem:

Ethereal shows me that my UDP scan loops constantly 
between port 43590 and 43591. 

This occurs for the two unfinished scan targets (244 & 245) 
in my x.x.x.241-245,255 scan. Both hosts reply with ICMP
port unreachables for the two ports.

The full command line is:

  nmap -sU -n -P0 -p- -r -vv -oA results -iL hosts-access

running on a

  Linux 2.6.11-1.35_FC3smp / Dual Intel Xeon 3.2

The nmap binary was compiled from the source rpm.

Are there any known problems with dual processor systems?

Here is a packet capture of the problem:

# tethereal -i eth2 udp or icmp
Capturing on eth2
  0.000000 y.y.y.5 -> x.x.x.245 UDP Source port: 43590  Destination port: 18437
  0.000255 x.x.x.245 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  0.110982 y.y.y.5 -> x.x.x.244 UDP Source port: 43591  Destination port: 18436
  0.111192 x.x.x.244 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  0.800954 y.y.y.5 -> x.x.x.245 UDP Source port: 43590  Destination port: 18438
  0.801155 x.x.x.245 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  0.911938 y.y.y.5 -> x.x.x.244 UDP Source port: 43590  Destination port: 18437
  0.912087 x.x.x.244 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  1.602902 y.y.y.5 -> x.x.x.245 UDP Source port: 43590  Destination port: 18439
  1.603056 x.x.x.245 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  1.713891 y.y.y.5 -> x.x.x.244 UDP Source port: 43590  Destination port: 18438
  1.714102 x.x.x.244 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  2.404854 y.y.y.5 -> x.x.x.245 UDP Source port: 43590  Destination port: 18440
  2.515840 y.y.y.5 -> x.x.x.244 UDP Source port: 43590  Destination port: 18439
  2.515999 x.x.x.244 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  3.205799 y.y.y.5 -> x.x.x.245 UDP Source port: 43591  Destination port: 18440
  3.205968 x.x.x.245 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  3.317795 y.y.y.5 -> x.x.x.244 UDP Source port: 43590  Destination port: 18440
  4.007759 y.y.y.5 -> x.x.x.245 UDP Source port: 43590  Destination port: 18441
  4.007975 x.x.x.245 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  4.119742 y.y.y.5 -> x.x.x.244 UDP Source port: 43591  Destination port: 18440
  4.119912 x.x.x.244 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  4.808709 y.y.y.5 -> x.x.x.245 UDP Source port: 43590  Destination port: 18442
  4.808875 x.x.x.245 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  4.920695 y.y.y.5 -> x.x.x.244 UDP Source port: 43590  Destination port: 18441
  4.920928 x.x.x.244 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  5.610657 y.y.y.5 -> x.x.x.245 UDP Source port: 43590  Destination port: 18443
  5.610890 x.x.x.245 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  5.722645 y.y.y.5 -> x.x.x.244 UDP Source port: 43590  Destination port: 18442
  5.722825 x.x.x.244 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  6.412607 y.y.y.5 -> x.x.x.245 UDP Source port: 43590  Destination port: 18444
  6.524604 y.y.y.5 -> x.x.x.244 UDP Source port: 43590  Destination port: 18443
  6.524841 x.x.x.244 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  7.214558 y.y.y.5 -> x.x.x.245 UDP Source port: 43591  Destination port: 18444
  7.214802 x.x.x.245 -> y.y.y.5 ICMP Destination unreachable (Port unreachable)
  7.326579 y.y.y.5 -> x.x.x.244 UDP Source port: 43590  Destination port: 18444
  [repeats from here]


TIA,

Marcus


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