[ubuntu] Question regarding Eth0 and Wlan0

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http://ubuntuforums.org – Hello, Lame start, but must appologise for any mistakes I'm prone on making while writing my question - I'm not a native english speaker. So, here goes ... I'm currently hooked to a BroadBand wireless Router, which supports both wired (ethernet) and wireless connections. I can use both of them at the same time - meaning I can connect to the eth0 port succesfully, but also to the wlan0. My question is : How can I choose on Ubuntu what connections should my programs use ? ; Meaning, say I want to download a torrent, I'd like to route 'Transmission Client' to wlan0, while Firefox/Chrome would (Hardware)