Support multiple IPs on the server

[dhpark21]

Hi
I have many ip of one interface card(Centos 7) as like below
eth0 10.10.10.10
eth0:0 10.10.10.11
eth0:1 10.10.10.12
eth0:2 10.10.10.13

but, if i connect 10.10.10.12 then all packet's are output on 10.10.10.10, not 10.10.10.12
how can i output packet to client request ip (of request port)
ex)
8081 port 10.10.10.11 <-> client A
8082 port 10.10.10.12 <-> client B
8083 port 10.10.10.13 <-> client C

Thanks

[fortuna]

Interesting use case!

I think this could be accomplished by getting the local address with Conn.LocalAddr() and setting the laddr on DialTCP() and DialUDP() (Dialer.Dial() doesn't have the laddr option).

[fortuna]

The new TCPService code should make that easier. We need to pass clientTCPConn.LocalAddr() to dialTarget here:

outline-ss-server/service/tcp.go

Line 258 in 264ddf9

tgtConn, dialErr := dialTarget(tgtAddr, &proxyMetrics, s.targetIPValidator)

UDP should be doable too.

[fortuna]

There's a difficulty in this situation:

• Server supports IPv4 and IPv6
• Client connects to a IPv6 server IP
• Client requests a connection to an IPv4 target
• Server can't use the IPv6 address to establish the IPv4 connection.

So we should check if the IP version of the target matches the IP version of the client. If it matches, we can use the IP the client connected to. Otherwise use whatever the system picks for you.