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skreien

Any way to get source TCP port

5 posts in this topic

#1 ·  Posted (edited)

Hey everyone,

I can't figure out a way to get the source TCP port of a connection. Here's the order of operations that I MUST follow due to interaction with another software:

1. Open connection (Source opens on a random high TCP port)

2. Send client name and class

3. Close socket so a FIN,ACK is generated

4. Open a listening socket on the same source port as the original socket

5. Receive information on connection

The server only sends its information if the socket is closed so it sees a FIN, ACK TCP sequence. I tried using TCPRecv after TCPSend, but that sends a RST, not a FIN, so it won't work. So how can I get the TCP source port that my original socket was sending on?

Thanks for any help. This one has me stuck.

Edited by skreien

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#2 ·  Posted (edited)

I only can offer you this, because i don`t have any idea about that.

A link to an UDF this will help you... and if i was you i will the search in other places like this MSDN Search there a lot of exaples in other languajes, and you have a lot of useful info.

Edited by monoscout999

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I'm not finding much of anything that (at the risk of sounding lazy) I can use without a whole lot of work. I really don't want to re-engineer a new tcpsend.

I had thought about parsing the output from netstat to find the port number, but that seems awfully heavy and unreliable.

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#4 ·  Posted (edited)

Thanks for the info monoscout999. I found something else that gave me what I was looking for but I don't think it's going to help.

I did find this link to that I tried, and it's giving me the correct port. However, the TCPReceive isn't working because the information that's coming back from the server really isn't on a new connection like what I'm expecting in AutoIt. Here's the sequence:

SYN

SYN ACK

ACK

send my client data now

FIN ACK

ACK

server sends data back

FIN ACK

Anyone know how I can match this cadence with AutoIt and receive the data? I've been playing with it for over a week, I still am stumped. Maybe it's not possible.

Edited by skreien

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I'm going to try posting this in the developers forum. Since they deal with the source maybe they will have an idea.

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