Can't communicate with servers on same subnet
 

The environment:

Two subnets: 192.168.0.x and 10.10.10.x. Servers are in 10.10.10.x.

Servers are Slackware of various releases.

Trying to add a new server. It is a replacement for an existing server so I have tried to set it up exactly like the existing server (except for the IP, of course.) All the servers have fixed IP's and are on the same hub. All the workstations have fixed IP's and are on the same hub.

These are the settings for the new server:

The gateway is 10.10.10.1.

The hosts file:

# For loopbacking.
127.0.0.1 localhost
10.10.10.10 apache.etrak-plus.com apache
10.10.10.11 mail.etrak-plus.com mail
10.10.10.15 etrak_directory
# End of hosts.

The host.conf file:

order hosts, bind
multi on

The resolv.conf file:

search etrak-plus.com
nameserver 66.0.214.14

One of the machines in 10.10.10.x is set up as a firewall and for port forwarding. The 10.10.10.1 is on that machine.

Route appears to give the correct information:

Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.10.10.0 * 255.255.255.0 U 0 0 0 eth0
loopback * 255.0.0.0 U 0 0 0 lo
default 10.10.10.1 0.0.0.0 UG 1 0 0 eth0

although there is a significant delay (20-30 seconds) before 'default' is displayed.

I can:

- ping 10.10.10.1 (the gateway) from the new server.
- ping all machines on the 192.168.0.x network from the new server.

I cannot:

- ping any machine (except the gateway) on the 10.10.10.x subnet from the new server but all the other servers can ping each other.
- ping the new server from any workstation (although this has worked from time to time and then just disappeared.)

arping quickly returns with 'Unicast...' and the correct hardware address but nothing else.

I have tested that it is a firewall issue by stopping the firewall... no difference.

Any ideas or pointers are appreciated.

TIA,

Carl

On the machine setup as the firewall do you have both 192.168 and 10.10 on the interface that connects to the lan? When you say port forwarding I'd think you mean between the WAN and LAN network cards and really mean packet forwarding.

You could add a route to each machine to see the 192.168 network is local.

route add -net 192.168.0.0 netmask 255.255.0.0 eth0

Ken,

Thanks for the reply.

Yes, the firewall machine has three NIC's: 192.168.0.1, 10.10.10.1 and 214.... (the Internet interface.)

I am less concerned about having the workstations be able to ping this server than I am about having this server be able to ping all the other servers (this one will be Tomcat and will need to communicate with the MySQL server on a separate box.) The puzzle for me is that all the servers (including this new one) are on the same subnet (10.10.10.x) yet this little bugger can't seem to ping the other servers.

Sometimes, I get the 'unreachable host' message but most of the time, ping just dies with no response (Example: ping 10.10.10.10 from new machine usually just dies.)

Any other ideas?

TIA,

Carl

Please paste the output of route -n and ifconfig