[techtalk] Netstat weirdness

[kelly at poverty.bloomington.in.us]

On Wed, 16 Aug 2000 10:24:15 -0400, "C. M. Martin" <caitlyn at netferrets.net> said:

>Oh, absolutely.  Specific host routes shouldn't be necessary, though
>I've tried them just in case.  The .56 is not a valid address on our
>network, though, which is what raised the red flag.

No, it's not a valid address on the network because it's the address
OF the network.

Here's the route list you gave earlier:
|Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
|63.251.67.56    0.0.0.0         255.255.255.248 U         0 0          0 eth0
|192.168.0.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1
|127.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 lo
|0.0.0.0         63.251.67.57    0.0.0.0         UG        0 0          0 eth0 

The way the kernel routes packets is, for each route table entry, in
order, it takes the IP address you're trying to reach, binary-ANDs it
with the genmask, and then compares the result with the destination.
If it matches, it sends the packet to the specified interface.  If the
G flag is NOT set, then this is a direct route; if G is not set, then
you're going out a gateway.  So, in your case, 63.251.67.56 thru
63.251.67.63 all go direct to eth0, 192.168.0.0 through 192.168.0.255
all go direct to eth1, 127.0.0.0 thru 127.255.255.255 all go direct
thru lo (the loopback interface), and everything else is gatewayed to
63.251.67.57 via eth0.  This is perfectly consistent with your
ifconfig settings.

The network on eth0 has the network address 63.251.67.56.  This should
not be the IP address of any machine on that network, since subnet
address 0 is reserved.  .56 is the network address and .63 is the
broadcast address for this subnet.

In short, there's doesn't appear to be anything at all wrong with your 
routing.

Kelly