Monthly Archives: March 2007

Utilisation de tubes anonymes et des signaux en C

Ce WE en voulant aider une amie à faire ses TP de système. Je me suis rendu compte que c’était difficile de trouver sur le net des exemples de code (qui marchent !) illustrant l’utilisation des pipes ou tubes anonymes en C. J’ai mis du temps à comprendre comment ça marchait car j’en avais fait mais très peu et il y a longtemps. Cependant, une fois qu’on a le principe ça marche tout seul !

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Changing MTU Over DHCP

Yesterday i wanted to change my local network configuration. I have been using static IP adresses for each computer so far and i thought it would be simpler to switch to a dhcpd-based configuration.

The problem is: I’m using IPv6 with my ISP and that requires to change the MTU to 1450 (instead of 1500 for standard ethernet) otherwise i wouldn’t be able to surf on IPv6 webservers (i would be waiting for the webpages to load forever…).

After a little search on google i found out it was really easy to autoconfigure the MTU over dhcp. There are two changes to make: one server-side and the other client-side.

On the server you have to add this to your /etc/dhcpd.conf

option interface-mtu 1450;

On the client you have to add interface-mtu to your /etc/dhclient.conf or /etc/dhcp3/dhclient.conf (depending on your *nix distribution):

request subnet-mask, broadcast-address, time-offset, routers, domain-name, domain-name-servers, host-name, netbios-name-servers, netbios-scope, interface-mtu;

Restart your dhcp server and run a dhclient and voilà ! The MTU should autoconfigure !