Hi, Gilad I remember that setsockopt(SO_BINDTODEVICE) will need root privilege. so can the hijack you mentioned work? Regards, xwz -----Original Message----- From: linux-net-owner@vger.kernel.org [mailto:linux-net-owner@vger.kernel.org]On Behalf Of Gilad Ben-Yossef Sent: 2004å1æ26æ 20:33 To: C Jagadish; linux-net@vger.kernel.org Subject: Re: Forcing packets through an interface in a multihomed machine Howdie, On Monday 26 January 2004 13:49, C Jagadish wrote: > Hi, > > How do I route packets to destination "A" through an interface > differnet from the entry in the routing table? ( In RedHat > Linux 7.2) I don't think you can do this exactly. However, you can limit a packet to go through a specific interface assuming you have a route through it even though normally this will not be the route chosen, by using the SO_BINDTODEVICE socket options. Attached is small example that creates a shared library that if preloaded (using LD_PRELOAD) will hijack all the socket() system calls and set this option on all sockets created, thus enabling to limit any executable to use a specific interface in a similar fashion to way the ping program -r option does for ping. It's a rather crude example, if you plan to make real use of it make sure to handle error conditions in saner fashion. A better way to choose the interface to route packets to is also a good idea :-) Cheers, Gilad -- Gilad Ben-Yossef <gilad@codefidence.com> Codefidence. A name you can trust (tm) http://www.codefidence.com "The future is here, it's just not evenly distributed yet." - William Gibson - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
