CODEWITHSUNDEEP
pythonnetwork-programmingtcppackets
Aran-Fey
Aran-Fey

Reputation: 43166

Is it possible to Inject packets into an existing tcp connection using Python?

As the title says, I would like to send data using an existing tcp connection. Said connection has already been established by a 3rd party program. I haven't been able to find much information about this, and it's safe to say I don't know how this will work at all.

The operating system is Windows. My preferred programming language is python - I'd prefer not to use 3rd party python modules, but I will if they make my life easier.

Just to clarify, in case you aren't sure what I want to do: I want to send data as if it were sent by a different program; pretty much like WPE pro's send function does.

Update:

Technically, couldn't I manually design the TCP packet and then tell the network device (or operating system) to send that packet? Wouldn't that be exactly the same thing an injected socket would do?

Edit: Wikipedia says the receiving host acknowledges packets it receives, which makes this a bit more difficult. But if can drop that acknowledge-packet before the 3rd party program receives it, then this should work. Right?

Upvotes: 3

Views: 5469

Answers (2)

user206545
user206545

Reputation:

A TCP session is not intended to be a many-to-one connection. Its a point-to-point stateful protocol which keeps track of packets that have been sent versus those that have been received by the other end. I don't believe you can inject yourself into an already-established session. Your best bet, as was pointed out previously, is to create a proxy and act as a man-in-the-middle interloper. Still not a trivial thing but doable.

Upvotes: 1

Doug T.
Doug T.

Reputation: 65609

Scapy/Pcapy are pretty powerful tools for monitoring and injecting packets into a live network interface. I've used them for several projects. These tools are ideal for stimulus/response low-level network protocols (ie DHCP, DNS, etc) and anything non-stateful sent over simple UDP.

Unfortunately, the TCP layer is very complicated and stateful. So injecting something that makes sense into the stream will be more difficult. Moreover, Scapy/Pcapy do not currently have support for tcp.

Upvotes: 1

Related Questions