I am using Gnottella and there doesn't seems to be a way of resuming a file from a different host. If the host was a modem user and they reconnect, their IP will change and a can't resume.

Is there any client that can check that the file is the same (using checksum/filelengh) and resume. Ideally I would like to click on the incomplete download and select "search for file".

[Is there any client that can check that the file is the same (using checksum/filelengh) and resume.]

Gnucleus can do this.

Greetings....

and it will do it without reporting your whereabouts to 5 different marketing companies

PHEX does it too, very effectiv, and automatically in fact.
I found V0.46 works better for me than the later one right now.

The latest Gnucleus version 1.3.3 is really outstanding now.

JD