Re: nexthost: failed to determine route to xxx.xxx.xxx.xxx

[Damian Gerow <dgerow () afflictions org>]

Thus spake kx (kxmail () gmail com) [12/04/06 10:54]:
: I don't have a BSD box around to try this out, but it would be
: interesting if you or someone else who could recreate the issue could
: run "nmap --iflist" (which calls getsysroutes), and trace the code and
: see which method is being used to fill in the route table and what is
: going on, and why nmap is only getting the routes for you loopback
: device (lo0).  If it is using the /proc/net/route method, you might
: try forcing that to fail in code, and then see what happens when it
: uses dnet.  If it is using dnet already, then dnet might need an
: upgrade.

No go.  I just upgraded dnet to 1.11, and it's still doing the same thing.
The scan here targets a host that is on the other side of pppoe0:


    # nmap -sT -v -v -d -P0 -O -p 80,81 192.168.0.1

    Starting Nmap 4.01 ( http://www.insecure.org/nmap/ ) at 2006-04-16 12:25 EDT
    WARNING: Unable to find appropriate interface for system route to 0.0.0.1

    WARNING: Unable to find appropriate interface for system route to 0.0.0.0

    nexthost: failed to determine route to 192.168.0.1
    QUITTING!
    # nmap --iflist

    Starting Nmap 4.01 ( http://www.insecure.org/nmap/ ) at 2006-04-16 12:28 EDT
    ************************INTERFACES************************
    DEV    (SHORT)  IP/MASK          TYPE        UP MAC
    lo0    (lo0)    127.0.0.1/8      loopback    up
    vr0    (vr0)    10.0.0.1/30      ethernet    up 00:50:BA:E8:08:B5
    fxp0   (fxp0)   172.19.206.8/24  ethernet    up 00:80:5F:F7:45:53
    ral0   (ral0)   192.168.132.8/24 ethernet    up 00:12:17:85:9A:3B
    fxp1   (fxp1)   10.9.22.8/24     ethernet    up 00:D0:B7:23:65:34
    pppoe0 (pppoe0) 64.7.134.90/32   point2point up

    WARNING: Unable to find appropriate interface for system route to 0.0.0.1

    WARNING: Unable to find appropriate interface for system route to 0.0.0.0

    **************************ROUTES**************************
    DST/MASK     DEV GATEWAY
    127.0.0.1/32 lo0 127.0.0.1
    127.0.0.0/0  lo0 127.0.0.1
    224.0.0.0/0  lo0 127.0.0.1

    #

Unfortunately, chasing this down within libdnet is a bit beyond me.  I'm
willing to work on it, but I need a few pointers (i.e. whereabouts to set
breakpoints, etc.).  I spent some time chasing it through, and the problem
is definitely within libdnet, but I don't know where.

  - Damian


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