ip routing table basics [closed]

Question

Could you please explain the following basic ip routing table:

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface

10.80.0.0       192.176.20.1    255.255.255.0   UG    0      0        0 eth0

192.176.100.0   *               255.255.255.0   U     0      0        0 int1

10.1.1.0        192.176.20.1    255.255.255.0   UG    0      0        0 eth0

10.13.1.0       192.176.100.1   255.255.255.0   UG    0      0        0 int1

192.176.0.0     *               255.255.0.0     U     1      0        0 eth0

default         192.176.20.2    0.0.0.0         UG    0      0        0 eth0

Answer 1

Well you have 2 local interfaces on the router; eth0 and int1. I guess it's easiest to go through line by line of the routing table.

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.80.0.0       192.176.20.1    255.255.255.0   UG    0      0        0 eth0

This states that any packet with a destination of 10.80.0.0/24 will be sent out eth0 using a gateway of 192.176.20.1.

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface   
192.176.100.0   *               255.255.255.0   U     0      0        0 int1

This states that any packet with a destination of 192.176.100.0/24 will be sent out int1 without using a gateway.

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.1.1.0        192.176.20.1    255.255.255.0   UG    0      0        0 eth0

This states that any packet with a destination of 10.1.1.0/24 will be sent out eth0 using a gateway of 192.176.20.1.

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.13.1.0       192.176.100.1   255.255.255.0   UG    0      0        0 int1

This states that any packet with a destination of 10.13.1.0/24 will be sent out int1 using a gateway of 192.176.100.1.

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.176.0.0     *               255.255.0.0     U     1      0        0 eth0

This states that any packet with a destination of 192.176.0.0/16 will be sent out eth0 without using a gateway.

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         192.176.20.2    0.0.0.0         UG    0      0        0 eth0

This states that any packet that doesn't match any of the above routes will be forwarded out eth0 with a gateway of 192.176.20.2. Most likely a route to the internet (also called Gateway of Last Resort, if I'm not mistaken).

If you need more information, don't hesitate to ask.

Extra info on the specifics: http://www.cyberciti.biz/faq/what-is-a-routing-table/