FreeBSD 6.0: Problem with network, doesn't use default gateway

[Greg Barniskis]

Christer Folkesson wrote:
> Hi, this is my first message to the mailing-list. I hope that I have 
> included
> enough information about the problem.
> 
> The problem is that my FreeBSD 6.0 (release) won't use the default route
> (gateway). So I can't access anything on the internet.
[snip]

I may have snipped some clue to what's actually wrong, but don't let 
that discourage you from trying to file complete problem reports. 
I'm a snipper. What I found to be most relevant follows.

> Internet:
> Destination        Gateway            Flags    Refs      Use  Netif Expire
> default            192.168.0.199      UGS         0       52   bge0
[snip]

This shows generally that the router IP is being properly used by 
FreeBSD as a gateway (Use = 52). Suggests that your assumption that 
FreeBSD isn't using the gateway properly is not correct.


> alcoy# traceroute ping.sunet.se
> traceroute to ping.sunet.se (130.242.80.31), 64 hops max, 40 byte packets
> 1  sentinel (192.168.0.199)  0.524 ms  0.518 ms  0.515 ms

[snip]

This shows the gateway IP is being properly used by FreeBSD as the 
appropriate route to ping.sunet.se. Indicates that the problem 
really is not FreeBSD's default route configuration or 
functionality. The route is clearly being used.


> alcoy# ping sentinel
> PING router.aqualize.tk (192.168.0.199): 56 data bytes
> 64 bytes from 192.168.0.199: icmp_seq=0 ttl=250 time=0.669 ms
[snip]

This shows you communicating with the gateway directly (confirms the 
assertion that local LAN operations are doing just fine).


Since your packets are being routed and NATed by the gateway 
correctly when the box is in Windows mode, packets should be getting 
routed and NATed correctly for FreeBSD as well. That is, if the box 
in Windows mode is using the same IP number and mask as the FreeBSD 
settings (you should double check that it is).

If the gateway is running fine (seems to be) and FreeBSD is properly 
using the gateway (seems to be), then the most likely suspect seems 
to be firewall configuration -- after your connection is properly 
routed, reply packets from the Internet could be getting dropped on 
the floor by your gateway or by FreeBSD.

Have you configured any kind of packet filter (ipf, ipfw, other) for 
FreeBSD? Try disabling that and see if your results change. If so, 
tune your filtering rules accordingly.

Use of tcpdump -i bge0 may also be informative (see man tcpdump).


-- 
Greg Barniskis, Computer Systems Integrator
South Central Library System (SCLS)
Library Interchange Network (LINK)
<gregb at scls.lib.wi.us>, (608) 266-6348