> > Will the Simple Source routing example shown in "LARTC HOWTO" work > > for a multihomed host (not a router) application that simply "binds" > > to the address associated with the interface or does the source > > routing decision only effect packets coming in over the interface and not > > from a local application? > > It effects all packets. > > > Basically, I want an application to choose which interface to use (i.e. > > override the default route) by doing something similar to the old days > > (Kernel 2.0.31 I think) when there was a socket option called > > SO_BINDTODEVICE. > > Can't you just let the application bind to the ip address of the interface? yes...this is exactly what I want to do. BUT....I am just beginning to learn about the "advanced routing" capabilities AND it is not clear to me how (or even if its possible) to set it up a multihomed linux host (not a router) to ensure that the outgoing interface is chosen based upon the bound to address and NOT the destination address. Prior to "advanced routing" the outgoing interface on a multi-homed host (not router) was chosen strictly on the destination address. The binding simply fixed the source address of the packet....regardless of the interface actually used. (One could thus have packets sent out eth0 whose source address were actually eth1) There was no source routing capability on a linux host, only linux routers. The SO_BINDTODEVICE was an early socket option to get around this. > > What do you mean by overriding default routes? Suppose I have a multihomed host with 2 interfaces (eth0,eth1) to 2 different ISPs. If I have set up the default route to be eth0 for all internet traffic, I want to be able to bind an application to eth1 and thus have that connections packets go out eth1 and NOT eth0. In other words, I want the routing decision to be based upon the bound to source address to take precedence over the destination default route rule. I know doing source routing is possible when the linux box is setup as a router. I am only considering setting up the box as a multi-homed host with all outbound traffic generated from local application processes. I do not presently have access to a multihomed host otherwise I would fiddle around to figure this out. Thanks, Steve
