SYN/ACK redirect

[JURNL]

Hello all,

(getting a bit crazy here)

PROBLEM:

- client 1 (behind router 1) requires to connect to client 2 (behind router 2)

- rendezvous server inbetween, having connections to both client 1 and 2


PROPOSED SOLUTION:

- connection from client 1 should be redirected to client 2
- client 1 informs server S about the request
- server S informs client 2 to connect
- client 1 AND 2 connect to S (ACK received)
- S reads ip/port/flag/sequence through rawsocket from both clients
- S swaps IP's, ports, flags and seq# to simulate 1 talking to 2, and vice versa

both clients receive SYN+ACK from other client, and the first arriving is used, the "slow" one dropped (like with simultaneous tcp open's...)


REAL PROBLEM:

I thought routers AND nic's would allow a new IP (aka server redirection) if the sequence was correct in the NAT... duh... not... RST is returned from both clients...

How do we get to the solution?

Jur

 

[Bas1234]

What router/data/VPN?

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It works! Now if only I could remember what I did...

Dain Bramaged
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[JURNL]

No VPN, various types of routers (should open up full/restricted cones as well)...

(thx Bas)

 

[Bas1234]

The best thing is to run a wireshark trace, then you can see what is going on.

___________________________________________
It works! Now if only I could remember what I did...

Dain Bramaged
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[JURNL]

Been there, did that, that's how I traced the RST coming back...

 

[Bas1234]

Sure you don't have a malware problem?
Try CCleaner or something else.
Also look at the services, it could be the server is busy. And then it could not handle multiple connections.

___________________________________________
It works! Now if only I could remember what I did...

Dain Bramaged
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