TCP (Transmission Control Protocol)

TCP (Transmission Control Protocol) is one of the core internet protocols. It delivers data between two computers reliably and in the right order: lost packets are sent again, and the receiver puts everything back in sequence.

How a connection works

Before sending data, the two sides open a connection with a three-step handshake. After that, data flows both ways until one side closes the connection or it times out.

TCP and mining

Miners connect to a pool over TCP using the Stratum protocol. The connection stays open the whole time the miner works: the pool sends jobs, the miner sends back shares.

Typical network problems on the miner's side:

• Timeouts and dropped connections — an unstable internet connection, Wi-Fi or a mobile modem.
• Packet loss and high latency — shares arrive late and become stale.
• Blocked ports — some providers, firewalls and antiviruses block uncommon ports; SSL or another port may help.

See also

• Stratum
• DNS
• SSL
• Latency