Interfaces configuration issues

hermeszdata · April 2010

on Ubanu 9.1

I am having issues with the configuration in my interfaces file. I have a block of 5 ip addresses (6 with the gateway) on network 173.*.*.200. I am using 173.*.*.201 as the ip address for my router connected to my cable modem. I have a Ubantu 9.1 server connected to one of the other 3 availble switchports of the cable modem with an ip address of 173.*.*.206 and apache2 webserver running.

I am able to ping the static ip address of the webserver, access the webserver via DNS and connect to the ftp server (all the same ip address) from any PC connected to my LAN, even with eth0 disconnected, without issues. With eth0 connected, I can ping WAN address, i.e. 4.2.2.2, without problems. However, no EXTERNAL users can connect to my webserver or even get a ping response. If I disconnect eth0 (the LAN interface) and try to ping 4.2.2.2 from the server, I get no response! I have even tried changing the configuration so eth0 is configured as the WAN interface with the same results.

The server is a Supermicro Dual Xeon 2.2G w/1GB memory, dual 10/100 NICs.

Here is the interfaces config.

auto eth0
iface eth0 inet static
        address 10.10.11.4
        netmask 255.255.255.224
        network 10.10.11.0
        broadcast 10.10.11.31
        gateway 10.10.11.1
        dns-nameservers 4.2.2.2
 
auto eth1
iface eth1 inet static
        address 173.*.*.205
        netmask 255.255.255.248
        network 173.*.*.200
        broadcast 173.*.*.207
        gateway 173.*.*.206
        dns-nameservers 68.87.85.98

What am I missing?

John

varelg · April 2010

From what you have given so far hermeszdata, which users do you refer to as "external"? It seems that the problem is outside of your LAN and is a routing problem of outside hosts and their routing to your server...

hermeszdata · May 2010

varelg wrote: »

From what you have given so far hermeszdata, which users do you refer to as "external"? It seems that the problem is outside of your LAN and is a routing problem of outside hosts and their routing to your server...

I guess the attachment is a bit confusing, but PacketTracer has its limits. I should have put in an additional cloud stub to represent "external" users and an additional link from the server to the LAN Switch (not possible in PT.)

My initial thought was there was an issue with the cable modem setup and I spent ~ 1 hour of wasted time talking to the ISP where they insisted the issue was with my server setup. The Cable Modem is set up as a pass "through device" so it is effectively transparent.

After my initial post, I tried several things. What I found was that if I disabled eth0, remote visitors could access the web/ftp server. This brings me back to the problems being how the server is configured.

John

georgemc · May 2010

Break open the help files and how-to docs and figure out how to update your routing table in the ubuntu server. In particular you need an all zeros route pointing to the outside world.

net 0.0.0.0 mask 0.0.0.0 gateway 173.*.*.<your router>

You may need to add similar outs to your router/switch also if you have a separate subnet behind the server.

George

hermeszdata wrote: »

I guess the attachment is a bit confusing, but PacketTracer has its limits. I should have put in an additional cloud stub to represent "external" users and an additional link from the server to the LAN Switch (not possible in PT.)

My initial thought was there was an issue with the cable modem setup and I spent ~ 1 hour of wasted time talking to the ISP where they insisted the issue was with my server setup. The Cable Modem is set up as a pass "through device" so it is effectively transparent.

After my initial post, I tried several things. What I found was that if I disabled eth0, remote visitors could access the web/ftp server. This brings me back to the problems being how the server is configured.

John

Interfaces configuration issues

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