EtherNet/IP

EtherNet/IP is an industrial network protocol that runs the Common Industrial Protocol (CIP) over standard, unmodified Ethernet and TCP/IP. TCP carries messaging such as configuration and diagnostics, and UDP carries real-time cyclic I/O data. It is managed by ODVA.

Source checked18/18 values · 2026-10-25

Specification

2 sources

Transports	tcp, udp
Architecture	producer consumer
Encoding	binary
Standard body	ODVA

Default ports

IANA assignments

44818TCPEtherNet/IP messaging

44818UDPEtherNet/IP messaging

2222UDPEtherNet/IP I/O

2221TCPEtherNet/IP over TLS

2221UDPEtherNet/IP over DTLS

Study notes

The IP stands for Industrial Protocol, not Internet Protocol.
CIP is the shared application layer, so the same object model also runs on DeviceNet and other CIP networks.
Port 44818 carries messaging and port 2222 carries cyclic I/O.

Safety

CIP Security adds TLS and DTLS (port 2221). Devices without it accept unauthenticated commands from anyone on the network.