Re: networking crash suddenly in my home LAN
The Thursday 24 July 2008 09:52:22 Csanyi Pal, you wrote :
> Alex Samad <alex@samad.com.au> writes:
> > On Wed, Jul 23, 2008 at 08:02:58PM +0200, Csanyi Pal wrote:
> >> Andrew Sackville-West <andrew@farwestbilliards.com> writes:
> >> > On Wed, Jul 23, 2008 at 02:35:31PM +0200, Csanyi Pal wrote:
> >> >> Andrei Popescu <andreimpopescu@gmail.com> writes:
> >> >> > On Wed,23.Jul.08, 13:31:13, Csányi Pál wrote:
> >> >> >> I have at home a small LAN with Debian GNU/Linux Etch boxes.
> >
> > [snip]
> >
> >> > /sbin/route
> >> >
> >> > when executed on the gateway machine.
> >>
> >> Kernel IP routing table
> >> Destination Gateway Genmask Flags Metric Ref Use
> >> Iface 91.102.231.32 * 255.255.255.240 U 0 0 0
> >> eth2 192.168.2.0 * 255.255.255.0 U 0 0
> >> 0 eth1 192.168.1.0 * 255.255.255.0 U 0 0
> >> 0 eth0 default 46-231-102-91.r 0.0.0.0 UG 0 0
> >> 0 eth2
> >
> > [snip]
> >
> > looking at your route table I would suggest something like
> >
> > tcpduump -pni eth2 port 53 or host <insert the isps dns ip address here,
> > the first one in the resolv.conf file>
> >
> > this will show you all the packets leaving via eth2 that are on port 53
> > (dns) or are destined or have come from you isp's dns server.
> >
> > if this is working from the gateway, try it from one of the remote
> > machines, the tcpdump should be still run on the gateway machine
>
> This is working from gateway. I'm trying it from LAN behind the
> gateway/firewall, from desktop machine.
>
> tcpdump now shows traffic, when I ping www.google.com from desktop
> machine.
>
> I run on gateway command:
> sudo tcpdump -pni eth2 port 53 or host 62.108.117.6
>
> listening on eth2, link-type EN10MB (Ethernet), capture size 96 bytes
> 09:42:10.158205 IP 91.102.227.98.46197 > 62.108.117.6.53: 1661+ A?
> www.google.com. (32)
> 09:42:15.153786 IP 91.102.227.98.50360 > 213.244.255.2.53: 1661+ A?
> www.google.com. (32)
> 09:42:20.153200 IP 91.102.227.98.46197 > 62.108.117.6.53: 1661+ A?
> www.google.com. (32)
> 09:42:25.152719 IP 91.102.227.98.50360 > 213.244.255.2.53: 1661+ A?
> www.google.com. (32)
>
> 4 packets captured
> 4 packets received by filter
> 0 packets dropped by kernel
>
> but I get error message on the command line on desktop (LAN):
> $ ping www.google.com
> ping: unknown host www.google.com
>
> tcpdump now shows traffic, when I 'ping 62.108.117.6' from desktop
> machine.
>
> I run the command on gateway:
> sudo tcpdump -pni eth2
>
> 09:46:56.951551 IP 91.102.227.98 > 62.108.117.6: ICMP echo request, id
> 63003, seq 10, length 64
> 09:46:57.083584 IP 91.102.227.98.50927 > 213.244.255.2.53:
> 58759+[|domain]
> 09:46:57.951463 IP 91.102.227.98 > 62.108.117.6: ICMP echo request, id
> 63003, seq 11, length 64
> 09:46:58.951366 IP 91.102.227.98 > 62.108.117.6: ICMP echo request, id
> 63003, seq 12, length 64
>
> but at the command line on desktop machine I get nothing:
>
> $ ping 62.108.117.6
> PING 62.108.117.6 (62.108.117.6) 56(84) bytes of data.
>
> Then I cancel it with Ctrl-C:
>
> --- 62.108.117.6 ping statistics ---
> 13 packets transmitted, 0 received, 100% packet loss, time 12008ms
>
> Well, I think that that something is wrong in my network setup, but
> what?
>
> --
> Regards, Paul Csanyi
> http://www.freewebs.com/csanyi-pal/index.htm
When you do a dhclient you get the IP address of the DHCP server which offer
you your IP. Could you try a ping on this address and if it works on the DNS
address you get in /etc/resolv.conf ?
--
Thomas Preud'homme
Why debian : http://www.debian.org/intro/why_debian
Reply to: