Re: Routers and resolv.conf: [was: extremely slow to ssh out from my machine]
From: Mitchell Laks (mlaks_at_verizon.net)
Date: 02/28/05
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Date: Mon, 28 Feb 2005 08:42:02 -0500 To: debian-user@lists.debian.org
Dear Michael,
Previous respondents said:
> > I agree with Lee about how your resolv.conf gets constructed. However the
> > problem still is that the router (who apparently behaves as if it were a
> > query-forwarding DNS server) doesn't respond to DNS queries... is there a
> > config option in your router to disable the router-internal DNS server
> > (and to forward the ISP nameservers directly)?
> > If not, you can only hardwire your resolv.conf to the two other
> > nameservers above, and prevent it from being rebuilt. (IIRC, there is a
> > package "resolvconf" that rebuilds this file on every reboot from various
> > sources, among them information received via DHCP - deinstalling it or at
> > least removing it from /etc/rc*.d/ should fix that)
> >
> > HTH,
> >
> > Jan (now replying from a different address)
>
> I'm at work now but will look into these when I get home this evening;
> thanks, Michael
I have had similar issues, and discovered that the 5 second (or perhaps in my
opinion two 10 second) pauses is in fact a reverse dns failure. You do ssh
192.168.1.25 and then (apparently) the tcpwrappers program asks "who is
192.168.1.25" to reverse dns.
Now you really dont care what the hostname is of 192.168.1.25 is, but the
tcpd tcp/ip daemon wrapper program by Professor Wietse Venema
is doing this checking
( look at
man 8 tcpd ,
man hosts.allow or
man hosts.deny).
So you can either set up a dnsserver on your router to answer questions like
this or alteranatively, just add a line to your /etc/hosts file of the
following sort
192.168.1.25 fred
where fred is the hostname of the box that is trying to ssh in. This will
immediately short circuit the whole reverse dns nonsense.
If you have a properly configured dns server all will work, but laptops tend
to have this problem when they point to dns servers on the internet when your
lan is disconnected from the internet.
I dont know why i didnt have this problem using fedora core or redhat 7.3. I
never configured a dns server before on my old machines which ran fedora and
they seem to have the same wrappers programs. So if i didnt want to set up a
dns server i just added stuff to /etc/hosts.
If you find out more let me know.
Mitchell Laks
>
>
> --
> Michael Bane
> Atmospheric Physics Group
> University of Manchester
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- Previous message: Patrick DUBAU: "Re: dell 2850 kernel 2.6.10 very slow (update)"
- In reply to: michael: "Re: Routers and resolv.conf: [was: extremely slow to ssh out from my machine]"
- Next in thread: Jan C. Nordholz: "Re: Routers and resolv.conf: [was: extremely slow to ssh out from my machine]"
- Reply: Jan C. Nordholz: "Re: Routers and resolv.conf: [was: extremely slow to ssh out from my machine]"
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