Date: Thu, 9 Jun 2005 10:15:44 -0400 From: Alan Curtis <alan.curtis@gmail.com> To: john@day-light.com Cc: freebsd-questions@freebsd.org Subject: Re: DNS problem? Message-ID: <19a27465050609071518e1e5cc@mail.gmail.com> In-Reply-To: <NHBBKEEMKJDINKDJBJHGMECOJCAD.john@day-light.com> References: <B869307A-128B-4770-A02D-A3B29C1198E6@gmail.com> <NHBBKEEMKJDINKDJBJHGMECOJCAD.john@day-light.com>
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On 6/8/05, John Brooks <john@day-light.com> wrote: > > 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=3D192.168.1.1 > > 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? >=20 > Probably... >=20 > > Do I have it right that I should point defaultrouter at the firewall? >=20 > Assuming that the firewall is your gateway to the outside world, then > yes. >=20 > > How do I tell FreeBSD about other DNS servers to use if the firewall > > route fails? >=20 > 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, the= n > their queries will never be answered. The effect is the same, you don't g= et > an answer. Unless they have some cached results that have not yet timed o= ut, > 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= . >=20 > > Why does pointing defaultrouter at the filewall fail? >=20 > Cable unplugged, switch down, nic dead, firewall down, upstream isp out, > isp router down, electricity out, hard drive on firewall crashed, dsl/cab= le > modem out, telco burped, and so forth for another hundred possible > reasons... >=20 > You could start troubleshooting by these steps: >=20 > 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 =3D 66.94.234.13) >=20 > As you proceed down this list it will give you clues as to what is wrong, > and tell you where to look. Good luck... >=20 > > Thank you John. I will try this series of pings the next time my server freezes. I did try something similiar, if not so methodical last time it froze and could ping most things on the interior. The firewall was still working as I could still access the outside using other computers on the network, so I think the problem was with the server somehow. Alan
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