Negative latency numbers shown for LAN ping scans

[Mantas Mikulėnas <grawity () gmail com>]

Writing here as suggested by
<https://twitter.com/bonsaiviking/status/497756679464042496>.

Using Debian jessie's current nmap (6.46), a local network ping scan
(-sn) reliably returns latency numbers smaller than expected:

| Nmap scan report for x.x.181.203
| Host is up (0.000082s latency).
| Nmap scan report for x.x.181.208
| Host is up (-0.10s latency).
| Nmap scan report for x.x.181.209
| Host is up (-0.10s latency).
| Nmap scan report for x.x.181.212
| Host is up (-0.099s latency).
| Nmap scan report for x.x.181.217
| Host is up (0.000060s latency).

Some numbers make sense, but I'm a bit concerned about the time-travel
in the middle; I'd have expected around 0.000212s if comparing to the
`ping` output.

(.203) rtt min/avg/max/mdev = 0.201/0.294/0.461/0.067 ms
(.208) rtt min/avg/max/mdev = 0.261/0.291/0.490/0.048 ms
(.209) rtt min/avg/max/mdev = 0.212/0.241/0.262/0.013 ms
(.212) rtt min/avg/max/mdev = 1.077/1.308/3.145/0.433 ms

Version information:

| Nmap version 6.46 ( http://nmap.org )
| Platform: i486-pc-linux-gnu
| Compiled with: liblua-5.2.3 openssl-1.0.1h-dev libpcre-8.35
libpcap-1.6.1 nmap-libdnet-1.12 ipv6
| Compiled without:
| Available nsock engines: epoll poll select

It's running Linux 3.14 (i686) on bare hardware.

-- 
Mantas Mikulėnas <grawity () gmail com>
_______________________________________________
Sent through the dev mailing list
http://nmap.org/mailman/listinfo/dev
Archived at http://seclists.org/nmap-dev/