Julia Evans

Day 22: Got some TCP packets back!

I spent a bunch of time with Jessica trying to send TCP packets to get the http://example.com homepage.

It turned out that the problem we were having was not at the TCP level, but actually at HTTP level: we needed to send something like

example.com\r\nAccept: */*\r\n\r\n"

to make the server actually reply. I then successfully reassembled a bunch of TCP packets into a webpage! I still need to

  • reply saying I got the packets (to the FIN-ACK, I think)
  • Make sure I don’t use duplicate packets when I reassemble
  • probably lots of things.

Today wasn’t super productive, I think because I gave a talk at NYC Python and I was a bit worried about it. The talk went well, though! So tomorrow I will hopefully get more done. We will see!

I really want to start writing “real” code again soon. Maybe tomorrow. This exploratory networking stuff is super fun and I’m learning a lot, but I feel like I haven’t written much code in a while and it is bothering me. Maybe a bittorrent client will come soon =)


Day 23: Started writing a TCP stack in Python Day 24: Unit testing this TCP library