Lan card not reaching Gateway

Linux and Unix-Like Linux
1

Hi,

I  have  this  problem on RHEL box. I am using  two NIC's of  same  model and make \(Intel 82557\) in the adjacent  PCI  slots . I  am using each one  for  different  subnet and have  assigned them ipaddresses and gateways  of  respective  subnets . While  one  is O.K. connecting  to its  gateway other  don't. I have  checked this  card in Winows  and  its  working fine. Card is not faulty. Problem   only starts in RHEL.

ip1 192.168.14.2 -----> gateway 192.168.14.1
ip2 172.16.18.3 --X--> gateway 172.16.18.1

Any help is aprreciated.

Thanks,

Dexter

2

What is the output of

 netstat -nr

?

3

Hi,

I have two subnets (172.16.18.0, 192.168.10.0) and a RH linux box. I know linux can act as router, but specifically want to ask if this acts as a router without any route addition on all nodes of two subnets. I mean , I need Not to add anything at each of the subnet nodes (obviously gateway is there) but only add routes in the linux box. I have checked enabling ip forwarding in files /etc/syscntl.conf and /proc/sys/net/ipv4/ip_forward. But that donot make any difference . I am unable to ping the node of 2nd subnet with the node of 1st subnet. My linux box has two nic's with 172.16.18.2 and 192.168.10.2

172.16.18.3 (node s1) ----> 172.16.18.2, 192.168.10.2 <---- 192.168.10.3 (node s2)

Firstly, is it achievable that by only adding routes on linux box I can make two subnets communicate. If yes then what route I need to put on this. (I donot want to add any route on the subnet nodes except the subnet gateway - 172.16.18.2 and 192.168.10.2)

Thanks in advance ,

Dexter

4

Try turning off the firewall on the RH box.

service iptables stop

And check that /proc/sys/net/ipv4/ip_forward has a value of 1.

5

I have merged these two threads as they relate to the same problem.

6

Hi
fpmurphy,

Firstly they do not point to same problem . First problem was that my node on one subnet was unable to connect to its gateway. BTW it is resolved now . May be some stucking at the network switch point was there. As I rebooted, it got OK.

My second post was one subnet not connecting to other with all ip forwarding done at the linux box connecting these.As you gave reply to stop firewall, I did that. But same status.

I am only able to reach the first subnet's gateway from the node in second subnet but this also bu putting route at node itself which I did not want. I am not getting what is going wrong. All posts I read on internet say these simple steps to make subnets communicate and I am doing them all, but still both subnets are unable to communicate .

/etc/sysctl.conf , ip-forwading = 1
sysctl -p
/sys/proc/net/ipv4/ip-forward, = 1
Firewall disabled

(From linux box , I am able to connect to nodes of both subnets.)

172.16.18.3 (node s1) ----> 172.16.18.2,
192.168.10.2 <---- 192.168.10.3 (node s2)

node 192.168.10.3 donot communicate with 172.16.18.2 (and so 172.16.18.3)

Any more suggestions ?

Thanks in advance

Dexter

---------- Post updated at 03:52 PM ---------- Previous update was at 03:50 PM ----------

Hi,

It is :

172.16.18.3 (node s1) ----> 172.16.18.2, ----------------------------
-------------------------- 192.168.10.2 <---- 192.168.10.3 (node s2)

subnet node 1 linux box subnet node 2

Dexter