On Mar 24 2001, bert hubert wrote: > If someone manages to write a reasonable explanation for the > 'onlink' option, I'll put it in the HOWTO ASAP. As far as I understand it, the situation is as follows: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Sometimes, you may want to send packets via a machine (i.e., a gateway) which is physically connected to your network, but to which you don't specifically have a route in your kernel routing table. In a situation like this, if you try to add a route through such a gateway, the kernel will perform consistency checks on the route you're trying to add and will detect that it doesn't know how to send packets to that gateway, rejecting the route. The "onlink" option of the "ip" command tells the kernel that the it does not have to check if the gateway is reachable directly by the current machine (i.e., the kernel does not need to check if the gateway is attached to the local network), so that you can insert your route in the kernel table without it being complained about. One possible use of this feature is when you're setting up a tunnel: you have to tell the kernel in some way that the other side of the tunnel is the gateway for your tunneled connection. But this other side is frequently very, very far away, only reachable via your default route (and, thus, the kernel doesn't have a direct route to it). So, to tell the kernel that the rest of your tunneled connection is reachable via this distant machine, you use the "onlink" option when you're setting this special kind of route. Of course, "onlink" should be used with caution. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Please let me know if this is acceptable. I could write with more details (giving a more concrete example), but I'm very busy right now. :-( I hope that this serves at least as a first approximation to the text that will be featured on the HOWTO. Hope this helps, Roger... -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Rogerio Brito - rbrito@xxxxxxxxx - http://www.ime.usp.br/~rbrito/ =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
