Configuring Routes

Routing is the act of transferring packets from one host or subnet to another. Let's say that you have two LAN subnets, 10.0.0.0/24 and 10.0.1.0/24, and a Linux router machine with two Ethernet cards, one connected to each subnet. The router has two IP addresses: 10.0.0.1 for eth0 and 10.0.1.1 for eth1. Figure 5-4 shows the two networks; the router's routing table looks like this (obtained by running route -n):

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.0.0.0        0.0.0.0         255.255.255.0   U     0      0        0 eth0
10.0.1.0        0.0.0.0         255.255.255.0   U     0      0        0 eth1

Furthermore, let's say that the hosts on each subnet have the router as their default gateway (10.0.0.1 for 10.0.0.0/24 and 10.0.1.1 for 10.0.0.0/24). Therefore, if 10.0.0.37 wanted ...

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