Bitcoin-Qt only 8 Connections

Note: This is fourth in a multipart post explaining various aspects of Bitcoin protocol.

In the previous posts, we first looked at a Bitcoin block and studied a binary .dat file to see how various elements in a Block are laid out. After studying the block, we wrote a basic block parser in python.

But the question remains, how did these blocks get on your computer? Today we seek answers to these questions by looking at the network and messaging layer of Bitcoin network.

We will analyze network traffic generated by Bitcoin-qt and peek into messages exchanged with other nodes. Since Bitcoin is a peer to peer network, the protocol includes mechanisms to discover other nodes. Further, since all nodes may not be at same version of protocol, there are mechanisms for handling version mismatches.

Wireshark

The best way to analyze network traffic is with a network dissector tool called Wireshark. You can download Wireshark from