# Networking reference

get-loopback String none

The `get-loopback` function returns the name of the machine loopback. On a UNIX system, that name is `localhost`.

get-tcp-service String Integer

The `get-tcp-service` function returns the name of the tcp service given its port number. For example, the tcp service at port 13 is the `daytime` server.

get-udp-service String Integer

The `get-udp-service` function returns the name of the udp service given its port number. For example, the udp service at port 19 is the `chargen` server.