ORPort

ORport is the TCP port on which a Tor relay listens for inbound connections from other relays and clients. It stands for Onion Routing Port and is a core component of how Tor relays form the network. When a relay starts, it binds to its ORPort and accepts TLS-encrypted TCP connections used to exchange relay descriptors, build circuits, and relay traffic as part of the onion routing process.

In operation, relays establish connections over the ORPort to share identity, bandwidth information, and configuration data, enabling the Tor network to construct paths through multiple hops. Clients also connect to relays via their ORPorts to participate in circuit construction, with directory services providing information about available relays and their capabilities.

Configuring ORport is done in the Tor configuration file (torrc). The ORPort directive specifies the port (and optionally the interface address) to listen on. For example, ORPort 9001 or ORPort [2001:db8::1]:9001. A relay may expose multiple ORPort directives to listen on different interfaces or ports. The directory port (DirPort) is a separate setting used to serve directory information to clients and is not the same as the ORPort.

Relays behind NAT or firewalls require proper port forwarding to the chosen ORPort so that other nodes can reach them. If the ORPort is not reachable, the relay will not appear in network metadata and cannot participate in circuit construction.

Security-wise, ORPort traffic is TLS-encrypted between relays; the privacy of end-to-end paths is preserved within Tor. The ORPort is essential for a relay’s participation in the Tor network and for maintaining overall connectivity.