Linux Routing Table

From route -n

 

Example;

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.29.42.103    0.0.0.0         255.255.255.255 UH    0      0        0     eth6
10.29.8.76        0.0.0.0         255.255.255.255 UH    0      0        0     eth6
10.28.10.0        0.0.0.0         255.255.255.0     U       0      0        0     eth6
192.168.8.0      0.0.0.0         255.255.254.0     U       0      0        0     eth7
23.128.16.0      0.0.0.0         255.255.240.0     U       0      0        0     eth7
 

The entries for 10.28.10.0 and 23.128.16.0 are applied automatically when, for example the following is added;  

iface eth7 inet static
address  23.128.28.20
netmask  255.255.240.0
network  23.128.16.0
#gateway  23.128.16.1

iface eth6 inet static
address 10.28.10.21
netmask 255.255.255.0
network 10.28.10.0
#gateway    10.28.10.1

Based on the above, we could read as;

Traffic destined for 10.29.42.103/32 (255.255.255.255) would be routed through the gateway 0.0.0.0 via the eth6 interface.

Traffic destined for 10.29.8.76/32 (255.255.255.255) would be routed through the gateway 0.0.0.0 via the eth6 interface.

Traffic destined for 10.28.10.0/24 (255.255.255.0) would be routed through the gateway 0.0.0.0 via the eth6 interface.

Traffic destined for 192.168.8.0/23 (255.255.254.0) would be routed through the gateway 0.0.0.0 via the eth7 interface.

Traffic destined for 23.128.16.0/20 (255.255.240.0) would be routed through the gateway 0.0.0.0 via the eth7 interface.

If there were 0.0.0.0 under the Destination column, this would indicate a Default Gateway.

I believe the below is more correct than the above for the 10.29.42.103

Destination     Gateway         Genmask             Flags Metric Ref    Use Iface
10.29.42.103    10.28.10.1    255.255.255.255 UH    0         0        0     eth6

which would read;

Traffic destined for 10.29.42.103/32 (255.255.255.255) would be routed through the gateway 10.28.10.1 via the eth6 interface. This could be achieved by ip route add 10.29.42.103/32 via 10.28.10.1 dev eth0

with the possibility of the below being more "normal";

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.29.42.103    10.28.10.1    255.255.255.0 UH    0         0        0     eth6

which would read;

Traffic destined for 10.29.42.103/24 (255.255.255.0) would be routed through the gateway 10.28.10.1 via the eth6 interface. This could be achieved by ip route add 10.29.42.103/24 via 10.28.10.1 dev eth0