problem in udp route for NIC with 2 ip and gateway

[H.H. Ding]

hi,

I have a server with 2 ip address

2: eth0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc pfifo_fast qlen 100
link/ether 00:20:ed:32:81:76 brd ff:ff:ff:ff:ff:ff
inet 61.164.49.39/26 brd 61.164.49.63 scope global eth0
inet 60.12.230.167/26 brd 60.12.230.191 scope global eth0:0

and default gateway is default via 61.164.49.1 dev eth0

It works for tcp.

Problem is, when client connect to 60.12.230.167 by udp, server will
response the package with source ip 61.164.49.39 and client drop the
packge.

How should I config to make the udp response with correct source ip
address?