Cfrtjryk

I have dual NIC machine running CentOS 6.7 and asterisk. First NIC is for LAN & Internet connectivity and second is for trunk provider's connectivity. Both of these have gateways configured. I don't seem to be able to access the Internet as the traffic is routed thru the Second NIC's gateway, also the second NIC is taken as default route by the kernel. I do not understand how default gateway is assigned in this case and what correction should I do.

Eth0 Config:

DEVICE=eth0

TYPE=Ethernet

ONBOOT=yes

NM_CONTROLLED=yes

BOOTPROTO=static

IPADDR=192.168.0.1

NETMASK=255.255.255.0

GATEWAY=192.168.0.100

DNS1=8.8.8.8

DNS2=8.8.4.4

Eth1 Config:

DEVICE=eth1

TYPE=Ethernet

ONBOOT=yes

NM_CONTROLLED=no

BOOTPROTO=static

IPADDR=10.165.11.139

NETMASK=255.255.255.248

GATEWAY=10.165.11.137

Ping Internet

ping 8.8.8.8

PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.

From 10.165.11.137 icmp_seq=1 Destination Net Unreachable

Ping SIP Trunk

ping 10.232.130.170

PING 10.232.130.170 (10.232.130.170) 56(84) bytes of data.

64 bytes from 10.232.130.170 (10.232.130.170): icmp_seq=1 ttl=253 time=3.14 ms

Routing Table

Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface

10.165.11.136   *               255.255.255.248 U     0      0        0 eth1

192.168.0.0     *               255.255.255.0   U     0      0        0 eth0

link-local      *               255.255.0.0     U     1002   0        0 eth0

link-local      *               255.255.0.0     U     1003   0        0 eth1

default         10.165.11.137   0.0.0.0         UG    0      0        0 eth1

Edit the eth1 config file and comment out/delete the gateway line and restart network service as follows:

service network restart

Now you should see 192.168.0.100 as your default router and everything should be working as expected.

By default, all the traffic related with the subnet of the eth1 interface, will go through that interface because the kernel will create that entry.

It's good to mention that all the traffic (except 10.165.11.136/255.255.255.248), will go through your default gateway, but in case you want to route some specific traffic through eth1 interface you can do as follows:

Runtime:

ip route add X.X.X.X/32 via 10.165.11.137 dev eth1

Permanent:

1. Create the file /etc/sysconfig/network-script/route-eth1
   


2. 
   

   Add a line like this

   
   
   

   
   

   X.X.X.X/32 via 10.165.11.137

   
   

   
   


3. 
   

   Restart network service to apply

   
   
   

   
   

   service network restart

   
   

   
   

I hope this helps.