Networking problem: can't connect to gateway

Tridus · n00b Joined: 04 Oct 2003 Posts: 12 Location: Canada

I've got a machine running Gentoo 1.4. It worked great when it was getting an address via DHCP.

I moved the machine and gave it a static IP. Now for some bizzare reason it can see ever machine on its local subnet, *except* its gateway. I can't ping the gateway but can ping everything else on the subnet.

The machine I can't ping is 216.194.67.1 in the setup. Since its also the gateway, the machine can't see the Internet. Anybody have any ideas?

(I'm not using ipv6 and have never done anything to set it up, I'm not sure why its even there.)

This is the output from ifconfig:
eth0 Link encap:Ethernet HWaddr 00:40:05:87:1D:1F
inet addr:216.194.67.76 Bcast:216.194.67.255 Mask:255.255.255.0
inet6 addr: fe80::240:5ff:fe87:1d1f/10 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:666 errors:0 dropped:0 overruns:0 frame:0
TX packets:59 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:44023 (42.9 Kb) TX bytes:7021 (6.8 Kb)
Interrupt:10 Base address:0x3000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

And this from route:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
216.194.67.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
127.0.0.0 127.0.0.1 255.0.0.0 UG 0 0 0 lo
0.0.0.0 216.194.67.1 0.0.0.0 UG 1 0 0 eth0

NeddySeagoon · Posted: Tue Dec 30, 2003 7:32 pm Post subject:

Tridus,

That all looks good. Are those routable IP addresses yours to allocate?
A whois shows they belong (are allocated) to a hosting company.

Maybe the gateway will only play with PCs in its DHCP address table. (That is it will not talk to PCs that it has not allocated an IP address to)

I can ping a lot of systems in that subnet too, but not your problem one. (I tried 1,2,3,75,76 and 77 in case its in your logs)
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Sareena · n00b Joined: 31 Dec 2003 Posts: 1

You are correct, we have two boxes that are being co-located with someone else.

They tell me that the gateway server is configured correctly for the new box.

They say the problem is with my IPv6 configuration.

Is there an easy way to disable IPv6?

Sareena

NeddySeagoon · Posted: Wed Dec 31, 2003 9:07 pm Post subject:

Sareena,

I have never used IP v6, sorry.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

compuboy86 · Tux's lil' helper Joined: 03 Apr 2003 Posts: 79

Maybe I missed this but it seems that you aren't setting the gateway in /etc/conf.d/net Mine, for example, is gateway="eth0/192.168.1.1"

NeddySeagoon · Posted: Wed Dec 31, 2003 11:38 pm Post subject:

compuboy86,

The route to the gateway is OK in the routing table though. However it got there.

Is /etc/resolv.conf OK? It shouls point to the nameserver, which may well be the gateway machine.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

compuboy86 · Tux's lil' helper Joined: 03 Apr 2003 Posts: 79

Post yours up...mine is fairly simple and yes, I do lookup hostnames through my gateway first before going to my isp. Here is mine:

domain myname.mydomain.com
nameserver 192.168.1.1
search myname.mydomain.com

My resolv.conf on my router is:
search dc.dc.cox.net
nameserver 68.100.16.25
nameserver 68.100.16.30
nameserver 68.9.16.30

The one on your router should be set (if DHCP) automagically by your ISP though.

symbiote · Posted: Thu Jan 01, 2004 11:28 am Post subject:

It has nothing to do with /etc/resolv.conf

He can't ping the IP address itself, hence, name resolution has nothing to do with it.

I've got a good feeling that the IP address you were getting from the DHCP server is subnetted, since most Class C networks are already subnetted anyway.

You assigned the IP statically as 216.194.67.76 with a netmask of 255.255.255.0, which tells that your network address is 216.194.67.0

However, in reality, that network may have been subnetted, meaning the .1 gateway could be in a different subnet already with a netmask of 255.255.255.128. Which is why you can't ping the gateway, or any other machines on the subnet, since your original Class C has been subnetted into two subnets (hence .128)

Find out what your subnet really is, and assign the IP statically with the proper netmask address and broadcast address.

Since you're a .76, and the gateway is a .1, i'm guessing that your proper settings should be:

IP: 216.194.67.76
Netmask address: 255.255.255.128
Broadcast address: 216.194.67.127

But that's just off the top of my head, but you can give it a try.
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Tridus · n00b Joined: 04 Oct 2003 Posts: 12 Location: Canada

Thanks for the replies everybody.

I CAN ping other machines in the subnet. I can ping 216.194.67.2 successfully, which tells me that its not a subnetting problem.

I can SSH into the other box (216.194.67.41) and from that connection SSH into the offending machine. 41 has the same gateway, and it works fine. The only difference between the two machines that I can tell is that 41 is older and doesn't have ipv6 support at all. (well, that and its an old mandrake installation)

I just don't understand why that would matter.

NeddySeagoon · Posted: Thu Jan 01, 2004 2:52 pm Post subject:

Tridus,

You have two boxes in the colo. One has no IP v6 support and works fine. The other has IP v6 support buts its not configured (well not deliberately anyway).

Does the gateway see IP v6 and try to use it but fall back to IP v4 if its not present?

That whould tie in with what you were told by the colo. Its your IP v6 setup thats the problem.

Have a read of man ifconfig esp the bit about removing an IPv6 address from the interface. Maybe that would help?
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Tridus · n00b Joined: 04 Oct 2003 Posts: 12 Location: Canada

I don't know if the gateway does that or not. They seem to think its the problem.

I recompiled the kernel without ipv6, here is the output now:

eth0 Link encap:Ethernet HWaddr 00:40:05:87:1D:1F
inet addr:216.194.67.76 Bcast:216.194.67.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:116 errors:0 dropped:0 overruns:0 frame:0
TX packets:52 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:12382 (12.0 Kb) TX bytes:6635 (6.4 Kb)
Interrupt:10 Base address:0x3000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
216.194.67.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
127.0.0.0 127.0.0.1 255.0.0.0 UG 0 0 0 lo
0.0.0.0 216.194.67.1 0.0.0.0 UG 1 0 0 eth0

I still think its something on their end, but I have no idea what that might be. Even if the gateway wouldn't forward for me, I should at least be able to ping the interface on the local subnet.

Tridus · n00b Joined: 04 Oct 2003 Posts: 12 Location: Canada

Just to let you all know that it is fixed now, and it was on their end. Thanks for the help everybody.