DNS problem?

[John Brooks]

> I am running a FreeBSD server behind a Linksys Wireless Access
> Point / Router (BEFW11S4). Its local address is 192.168.1.1. The
> Linksys is attached to a DSL modem.  In my /etc/rc.conf file I have
> defaultrouter=192.168.1.1
> which works most of the time. However occasionally, all network
> traffic freezes, I cannot login to the server using ssh and my
> mailing lists and websites do not function. If, at my server, I type
> "host someip.com" it reports 'no server can be found' or some similar
> message (I sorry, I didn't note down the exact message) - a reboot
> has fixed the problem.
>
> I assume that the problem is that the server is unable to find a DNS
> server. Is that right?

Probably...

> Do I have it right that I should point defaultrouter at the firewall?

Assuming that the firewall is your gateway to the outside world, then
yes.

> How do I tell FreeBSD about other DNS servers to use if the firewall
> route fails?

If your resolving dns servers as listed in /etc/resolv.conf are outside
the firewall, then they cannot be reached if the default route is down.
Likewise if your resolving dns servers are inside or on the firewall, then
their queries will never be answered. The effect is the same, you don't get
an answer. Unless they have some cached results that have not yet timed out,
but even with the cached answer you still cannot reach the destination,
so the end effect is the same - you know where to go but cannot get there.

> Why does pointing defaultrouter at the filewall fail?

Cable unplugged, switch down, nic dead, firewall down, upstream isp out,
isp router down, electricity out, hard drive on firewall crashed, dsl/cable
modem out, telco burped, and so forth for another hundred possible
reasons...

You could start troubleshooting by these steps:

1) ping 127.0.0.1
2) ping ip of local machine
3) ping localhost
4) ping hostname of local machine
5) ping another host on same lan by ip address
6) ping another host on same lan by hostname (if any exist in /etc/hosts)
7) ping interior ip of firewall (192.168.1.1)
8) ping exterior ip of firewall
9) ping default gateway of firewall
10) ping ip address of some internet host (yahoo.com = 66.94.234.13)

As you proceed down this list it will give you clues as to what is wrong,
and tell you where to look. Good luck...

>
> Thanks
>
> Alan
>
>