Re: [PATCH] make nmap work in certain network setups

[David Fifield <david () bamsoftware com>]

On Thu, Jul 23, 2009 at 10:04:25PM +0400, Dmitry V. Levin wrote:
> Looks like nmap fails to run from root user in certain network setups, e.g.
> inside OVZ container where main network interface (venet0) has no IP
> address and IP addresses are assigned to its aliases (venet0:1, etc.).
> In such setup, nmap aborts with the following diagnostics:
>
> Failed to find device venet0 which was referenced in /proc/net/route
> Failed to find device venet0 which was referenced in /proc/net/route
> nexthost: failed to determine route to [real IP address]
> QUITTING!
>
> Proposed patch workarounds this problem by considering interface aliases
> when main interface mentioned in the route file has no IP address.
>
> Better fix for this and other routing issues would be to use RTM_GETROUTE
> netlink API instead of manual route determination, but such change to the
> code is going to be more intrusive.
>
> Another problem with nmap in the aforementioned network setup is that it
> fails later with the following diagnostics:
>
> Failed to lookup subnet/netmask for device (venet0): venet0: no IPv4 address assigned
> QUITTING!
>
> This happens because pcap_lookupnet() is being called with normalized
> device name instead of full device name.  It looks like a bug, and
> proposed patch fixes this issue, too.

I was able to reproduce the second error message but not the first with
        ifconfig eth0 0.0.0.0
        ifconfig eth0:1 192.168.0.21
        route add default gw 192.168.0.1

The patch fixes the second error message for me and the first part of it
looks corerct as well. I applied it in r14615.

David Fifield

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