"Cameron Kerr" <cameron.kerr@paradise.net.nz> wrote in message
news:slrnbvpbko.dsv.cameron.kerr@orloc.localdomain ...
> On 2004-01-07, Geoff <geoff_r@canada.com> wrote:
>
> > Setup:
> > WAN
> > |
> > 3Com <--> Router <--> Other PC
>
> This is unclear. Is the 3Com connected to the Router, or to the WAN, or
> is the WAN, Router, and 3Com connected to the same switch/hub? Is 3Com
> supposed to be another router?
Sorry the picture didn't work... the WAN is connected to the router (it's
WAN port) while the PC and 3COM (in the redhat machine) are on the LAN side
of the router.
> Please supply more topology information (IP addresses, connection info,
> routes, subnet information.)
I'm not sure what other info you want that isn't below ...
subnet is 172.16.37
masks for both PC and Linux are 255.255.255.0
> > Output of "ping 172.16.37.15" (PC connected to router)
> > ---------------------------------------------------------------
> > PING 172.16.37.15 (172.16.37.15) 56(84) bytes of data
> > From 172.16.37.20 icmp_seq=1 Destination Host Unreachable
> > From 172.16.37.20 icmp_seq=2 Destination Host Unreachable
> > From 172.16.37.20 icmp_seq=3 Destination Host Unreachable
> > From 172.16.37.20 icmp_seq=4 Destination Host Unreachable
> > From 172.16.37.20 icmp_seq=5 Destination Host Unreachable
> > From 172.16.37.20 icmp_seq=6 Destination Host Unreachable
> > From 172.16.37.20 icmp_seq=7 Destination Host Unreachable
> > From 172.16.37.20 icmp_seq=8 Destination Host Unreachable
> > From 172.16.37.20 icmp_seq=9 Destination Host Unreachable
> > CNTRL-C
> > ---- 172.16.37.15 ping statistics ---
> > 12 packets transmitted , 0 received, +9 errorrs, 100% packet loss,
> > time 11077ms, pipe 3
> > ---------------------------------------------------------------
>
> From this I can tell two things. First, packet's are going out, but
> something (most likely the Router) is saying that the host is
> unreachable. (Although the output of 'ifconfig -a eth0' would seem to
> indicate that there is nothing coming in, so the sending host must be
> realising that itself (such as a routing problem). The total time would
> indicate that its not being delayed significantly.
I have checked with a packet sniffer on the PC and the packet does arrive at
the PC (and is replied to).
> > Output of ifconfig -a eth0 has the following :
>
> > RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> > TX packets:16 errors:0 dropped:0 overruns:0 frame:0
>
> > Contents of /proc/interrupts: (just line 5 and last 2)
> > ---------------------------------------------------------------
> > 5: 0 XT-PIC eth0
> > NNT: 0
> > ERR: 0
>
> Further indication that its not receiving anything off the wire.
I'm wondering if the NIC's (3Com) interrupt is not be noticed/processed..
(I'm sure there are interrupts as there is traffic in the form of pings
to/from the PC)
> > netstat -r gives the following :
> > ---------------------------------------------------------------
> [reformatted]
> > Destination Gateway Genmask Iface
> > 172.16.37.0 * 255.255.255.0 eth0
> > 169.254.0.0 * 255.255.0.0 eth0
> > 127.0.0.0 * 255.0.0.0 lo
> > default 172.16.37.254 0.0.0.0 eth0
> > ---------------------------------------------------------------
>
> Hmm, one wishes that you would list the IP addresses and routing tables
> of all the machines involved. One possible reason for not receiving
> anything back is that the route-back is not set, or is set incorrectly.
>
> BTW, '/sbin/route -n | cut -b-48,72-' gives something easier to look at
> in a post.
>
> > I have no clue why 169 is there... I did remove it after a previous
> > install with no differences
>
> I think I may be able to explain the 169. Microsoft gives its
> unconfigured devices numbers in that range, so that unconfigured devices
> can be found (and configured, one would assume).
>
> You should also make sure that the Router is set to forward IP.
> 'cat /proc/sys/net/ipv4/ip_forward' should output 1.
When I run look at /proc/sys/net/ipv4/ip_forward it is 0 - what does this
mean ?
>
> You might also try employing tcpdump on the router if you can to make
> sure that its receiving anything. This should tell you plenty about
> what's going on.
>
> --
> Cameron Kerr
> cameron.kerr@paradise.net.nz : http://nzgeeks.org/cameron/
> Empowered by Perl!