Hi: I'm writing a UDP server and meet a problem the UDP server program is run on a box with single card but has multi ip: like eth0 10.0.0.1 eth0:1 10.0.0.2 eth0:2 11.0.0.1 I bind the server socket with INADDR_ANY when a client send a packet to 10.0.0.2(the eth0:1 's ip) the server can recieve the packet and reply, but the client can't recieve the server's response I use wireshark to capture the response packet and found that the server use 10.0.0.1(the eth0 's ip) as saddr in the response packet I expected it to be 10.0.0.2 but it's not my question : is there any way to let the UDP server relpy just use the ip it receieved the request ? It's : when a client send a request to 10.0.0.1(eth0); the server use 10.0.0.1 to response and another client send a request to 10.0.0.2(eth0:1); the server use 10.0.0.2 to response Thanks. 2011-10-15 jiangtao.jit