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Posted

Hi Guys,

 

I've had a quick read around and cant see anything that would help, so I figured id ask :D

 

I have a redhat linux box with 2 network cards:

 

External [eth0]

IPaddress: 192.168.115.10

mask: 255.255.255.0

Gateway: 192.168.115.1

 

Internal [eth1]

IPaddres: 192.168.0.1

mask: 255.255.0.0

Gateway: 192.168.0.254

 

I can ping and access the machine from internal, but not externally.

 

Initially I thought routing table problems: was it sending the request to the external card and trying to reply with the internal??

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.115.0   192.168.115.1   255.255.255.0   UG    0      0        0 eth0
192.168.115.0   *               255.255.255.0   U     0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth1
192.168.0.0     192.168.0.254   255.255.0.0     UG    0      0        0 eth1
192.168.0.0     *               255.255.0.0     U     0      0        0 eth1
default         192.168.115.1   0.0.0.0         UG    0      0        0 eth0

 

It doesnt appear so.

 

I figured id try and trace route to its external address.

 

traceroute to 212.248.*.* (212.248.*.*), 30 hops max, 38 byte packets
1  192.168.115.10 (192.168.115.10)  3000.754 ms !H  3000.518 ms !H  3000.391 ms !H

 

Ok - so can it ping itself externally?

PING 212.248.*.* (212.248.*.*) 56(84) bytes of data.
From 192.168.115.10 icmp_seq=1 Destination Host Unreachable

 

Doesnt appear so.

 

I get the feeling I've been working on this for that long that its a case of cant see the wood for the trees, and im missing somthing really obvious.

 

If anyone has any suggestions or need me to provide more details in order to help then please just ask away.

 

Any help is greatly appreciated.

 

Cheers.

Posted
Some routers will not, or are not configured, to connect machines from internal to external and back again. I was tearing my hair out one day trying to do something similar to what you are only to discover that all was setup correctly but I could not connect to my webserver's external ip address from the internal network. This might not be the case, but it would be easy for you to check.
Posted

External [eth0]
IPaddress: 192.168.115.10
mask: 255.255.255.0


Internal [eth1]
IPaddres: 192.168.0.1
mask: 255.255.0.0

 

would it cause a problem that eth0 is within the same subnet as eth1? it looks odd to me.

  • 2 weeks later...
Posted
would it cause a problem that eth0 is within the same subnet as eth1? it looks odd to me.

 

Network masks are conflicting. The host is going to get confused as to which interface to use to get to 192.168.115.1. If you want to test this take down the internal interface (e.g. ifconfig eth1 down), or unplug it and it will work fine and dandy.

 

I'd suggest using a different internal IP range/netmask if at all possible?

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