Well, I think the first thing to do would be to finish defining what the task is, in terms of what specific sort of output(s) you really want; this will help to figure out what sort of data structure to use.

What you've said so far about the task is:

count the number of packets from one ip to another ip within the same port

but I don't quite understand what that means. Based on the code you've posted, you apparently start with an input list that has two IP addresses per line (separated by ' > '), with or without a port number on one or both addresses.

Can you give a brief but specific example of some actual input, along with the desired output it should produce? I'm afraid I can't guess this from what you've said so far.