Reply To: Re-routing TCP packets

Home Forums Discussions Support Portal Re-routing TCP packets Reply To: Re-routing TCP packets



Hi bk, yes I see what you mean.

Okay I’ll try to explain what I try to achieve.
I’m writing an antispam application that runs as a local POP3 proxy server, standing between the mail client and the remote server. I want to avoid the user all the complexity of modifying his mail client’s account settings to point to the POP3 proxy, so I want to transparently reroute outgoing packets to remote server to the local POP3 proxy. Then the POP3 proxy establishs the real connection to the remote server, grab new mails, filter them and reply to the mail client through the rerouted connection. The mail client needs to believe he’s connected to remote server while he’s actually connected to the local POP3 proxy.

So we have:

User PC @
– mail client (Outlook, etc)
– POP3 proxy (server listening on port 110)
– winpkfilter packet router

POP3 host @

When the winpkfilter packet router detects a connection < -> / 110, he’ll change the destination IP and port to local POP3 proxy.

BTW, about my prior message :

PCA -> RST -> PCB (ZeroWindow)

I ran this between 2 PCs in my local network. I’ve never been to make it work on the same machine as I’d like to according to this message.