[ale] Network setup

[Joe Steele]

> Rajit's IP address: 190.160.1.26
> Nitin's IP address: 190.160.1.27
> 
> >From Rajit's machine:
> 
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric Ref    Use
> Iface
> 190.160.0.0     190.160.1.26    255.255.0.0     UG    0      0        0 eth0
> 190.160.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth0
> 127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        0 lo
> 0.0.0.0         190.160.1.26    0.0.0.0         UG    0      0        0 eth0

Some obvious problems with this configuration:

1)  The first and second route entries are conflicting;  the first says to 
use a gateway for net 190.160.0.0 while the second says that net 190.160.0.0 
is directly connected to eth0.

2)  Regarding the first route entry:  Except when you are trying to do something 
special, it is unusual to route traffic to a net (190.160.0.0) through a 
gateway (190.160.1.26) on that same net.  (The logic is that if host 190.160.1.26 
is directly accessible, then the entire net should also be, therefore no gateway 
is needed.)

3)  Regarding the  first and fourth entries:  You say this is the routing table 
from Rajit's machine, whose IP address is 190.160.1.26.  It is incorrect for a 
Linux box to list its own IP address as a gateway in its own routing table.  This 
will result in the packets being sent out eth0 with both the source and 
destination ethernet/MAC addresses being that of eth0.  The intended recipient 
will never see the packets because they are destined to the wrong MAC address, 
even though they go out the proper interface with the proper IP destination.

Since you've said your network consists of only two boxes, you probably should 
delete the first and fourth route entries, keeping the second and third.  Use the 
same route entries on both boxes.

--Joe
--
To unsubscribe: mail majordomo at ale.org with "unsubscribe ale" in message body.