Re: DNS and router

Following on from my adventures last year ...

Moe Trin wrote:
On Mon, 18 Dec 2006, in the Usenet newsgroup comp.os.linux.networking, in
article <em5mj9$66f$1@xxxxxxxxxxxxxxxxxxxxxx>, AAW wrote:



Then the nameserver setup ON THE LAPTOP is incorrect. Either, it is
trying to ask the "wrong" nameserver, or it does not know about
name servers.


If I connect the laptop directly to my router/modem it works fine. If, however, I connect it to my server and then the server tot he router/modem it doesn't work. Would that not suggest that the problem is on the sever even if it it manifested on the laptop?

This is what I get on the server (using tcpdump) when I do a dig on the laptop:


11:39:15.177856 IP 192.168.1.254.filenet-rpc > server.localdomain1.domain: 43550+ A? pat.uio.no. (28)
11:39:15.177955 IP server.localdomain1 > 192.168.1.254: ICMP host server.localdomain1 unreachable - admin prohibited, length 64
11:39:20.095915 IP server.localdomain1.netbios-dgm > 192.168.1.255.netbios-dgm: NBT UDP PACKET(138)
11:39:20.095972 IP server.localdomain1.netbios-dgm > 192.168.1.255.netbios-dgm: NBT UDP PACKET(138)
11:39:20.175576 arp who-has 192.168.1.254 tell server.localdomain1
11:39:20.175682 arp reply 192.168.1.254 is-at 00:0f:b0:49:e4:90 (oui Unknown)
11:39:20.179163 IP 192.168.1.254.filenet-rpc > server.localdomain1.domain: 43550+ A? pat.uio.no. (28)
11:39:20.179242 IP server.localdomain1 > 192.168.1.254: ICMP host server.localdomain1 unreachable - admin prohibited, length 64
11:39:25.178669 arp who-has server.localdomain1 tell 192.168.1.254
11:39:25.178704 arp reply server.localdomain1 is-at 00:50:fc:08:bc:49 (oui Unknown)

I can ping the server (192.168.1.1) from the laptop (192.168.1.254).


So, your next task is to look on the laptop in the
files /etc/resolv.conf and /etc/nsswitch.conf and /etc/host.conf
and compare these to the files on your router.


on the laptop:

resolv.conf

; generated by /sbin/dhclient-script
nameserver 192.168.1.1

nsswitch.conf

#
# /etc/nsswitch.conf
#
# An example Name Service Switch config file. This file should be
# sorted with the most-used services at the beginning.
#
# The entry '[NOTFOUND=return]' means that the search for an
# entry should stop if the search in the previous entry turned
# up nothing. Note that if the search failed due to some other reason
# (like no NIS server responding) then the search continues with the
# next entry.
#
# Legal entries are:
#
# nisplus or nis+ Use NIS+ (NIS version 3)
# nis or yp Use NIS (NIS version 2), also called YP
# dns Use DNS (Domain Name Service)
# files Use the local files
# db Use the local database (.db) files
# compat Use NIS on compat mode
# hesiod Use Hesiod for user lookups
# [NOTFOUND=return] Stop searching if not found so far
#

# To use db, put the "db" in front of "files" for entries you want to be
# looked up first in the databases
#
# Example:
#passwd: db files nisplus nis
#shadow: db files nisplus nis
#group: db files nisplus nis

passwd: files
shadow: files
group: files

#hosts: db files nisplus nis dns
hosts: files dns

# Example - obey only what nisplus tells us...
#services: nisplus [NOTFOUND=return] files
#networks: nisplus [NOTFOUND=return] files
#protocols: nisplus [NOTFOUND=return] files
#rpc: nisplus [NOTFOUND=return] files
#ethers: nisplus [NOTFOUND=return] files
#netmasks: nisplus [NOTFOUND=return] files

bootparams: nisplus [NOTFOUND=return] files

ethers: files
netmasks: files
networks: files
protocols: files
rpc: files
services: files

netgroup: files

publickey: nisplus

automount: files
aliases: files nisplus


host.conf

order hosts,nis,bind


On the server:

resolv.conf

# generated by NetworkManager, do not edit!

nameserver 195.67.199.42
nameserver 195.67.199.43

nsswitch.conf

same as for the laptop

host.conf

order hosts,bind


They all look ok to me? Do they to you?


All of this shows normal operation. The only problem was the query to the
nameserver for '2.0.168.192.in-addr.arpa'. This is a RFC1918 address
(192.168.0.2) and a public name server won't know the answer. As this
seems to be your address, this should normally be solved by have this
data in the '/etc/hosts' files in the form

192.168.0.2 full.name.of.this.host shortname


This is what I have in hosts on the server:

# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
192.168.0.2 server2.localdomain2 server2
192.168.1.1 server.localdomain1 server



Did any of that help? Any ideas why DNS doesn't work from the laptop?


Thanks again for your time.

.

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