How to increase MTU size on Linux 2.6?
Is such a thing possible? If yes, which files (in
/etc or elsewhere) must one edit?
I'd warn you not not to do it unless you are really certain, that this is what you really want (like having two servers directly connected by cross-over cable over Gigabit Ethernet interfaces).
There's already PMTUD algorithm, which is able to deduce MTU size across the path. And when rising MTU above that you'll either experience some packet loss or will make network-administrating guys sad, because their routers and switches will have to fragment your packets using CPU as opposed to fast routing with ASICs.
If that's what you want, then you may want to see http://wiki.archlinux.org/index.php/Jumbo_Frames, which has some nice numbers and hints. The basic command is
Assuming you mean MTU (Maximum Transmission Unit), check out this article (should be similar across Linuxen)
I think it's in the
area. There will be 'iface' entries. Locate your interface and change the mtu line (or add one at the end if there is none).
Just remember that this is not magic. If you increase the MTU too much, you will have network problems.
To check without 'burning' the configuration into your /etc files, you can try
where, eth0 is your interface name. This change will be lost on reboot.