Server 2008 R2 FTP Stalls – Troubleshooting Guide

By default, on Linux, if an interface has multiple addresses that are on different subnets, traffic destined for the respective subnets will have the proper source IP. That is, if eth0 has two addresses 192.168.1.1/24 and 10.1.1.1/8, then traffic to anything on the 10.0.0.0 subnet will have source 10.1.1.1, and traffic to anything on the 192.168.1.0 subnet will have source 192.168.1.1. You can also assign source addresses explicitly in this case by using the "src 1.2.3.4" option to "ip route".

In your case, though, all your addresses are on the same subnet, so the "primary" one (as revealed by "ip addr list dev eth0") is used as the source IP for traffic exiting on that interface. I think it's possible to control the source IPs in this case just using "ip route", but I've found it easier to use iptables to rewrite the source addresses for traffic of interest.

If you want to force a specific source address to be used for specific destinations, you can do it with a SNAT rule:

iptables -t nat -I POSTROUTING -o eth0 -d dest-IP-or-net/mask -s primary-IP-of-eth0 -j SNAT --to-source desired-source-IP

So if your "primary" eth0 IP is 192.168.100.1, but you want traffic to 1.2.3.4 to have a source of 192.168.100.2, then do this:

iptables -t nat -I POSTROUTING -o eth0 -d 1.2.3.4/0 -s 192.168.100.1 -j SNAT --to-source 192.168.100.2

Note that the "-s 192.168.100.1" is important: it prevents forwarded traffic's source addresses being rewritten by this rule.

If you are going to implement complex network configurations on Linux, you should read the Linux Advanced Routing and Traffic Control documentation, http://lartc.org

You don't. rsync can't do that for you, it is a protocol of its own and doesn't work over FTP.

You might, however, want to try csync. IIRC it provides rsync-like behaviour over HTTP. I can't comment on whether it works over FTP, you'll have to try it.