[plug] Another network question

[Craig Ringer]

> ifconfig lo:1 10.0.1.1
> 
> Some form of aliasing according to the context I got it from, but I'm not sure 
> what aliasing means in network terminology.

It's a linux thing as much as a general networking thing. Basically, 
what your're doing is creating a second "virtual" network interface 
attached to the real interface, that can have a different IP address 
etc. It is a way of having multiple virtual network interfaces on a 
single physical interface (and medium).

In this case, your "physical" interface is also virtual, being the 
loopback interface. So perhaps "real" or "primary" would be better words 
than "physical".

10.x.x.x is one of the private address spaces, like 192.168.x.x .

 > Also, "lo" seems special to this sort of usage; I
> tried changing it and got a "no such interface" error.

ifconfig -a

will show you "lo" and probably "eth0" and/or "ppp0" . These are network 
interfaces. "lo" is the loopback interface, and is how packets going 
between programs on the local computer get transmitted.

what you're doing is creating an alias on the loopback interface, then 
assigning an IP address from a private network to it. This can be handy 
in simulating networks, but I generally use a dummy network interface 
instead (modprobe dummy ; ifconfig dummy0 10.0.1.1).

man ifconfig