SERVICES(5) | File Formats Manual | SERVICES(5)

# NAME

`services` — service name database

# DESCRIPTION

The `services` file contains information regarding the known services available in the Internet. For each service, a single line should be present with the following information:

    official service name
    port number
    protocol name
    aliases

Items are separated by any number of blanks and/or tab characters. The port number and protocol name are considered a single item; a slash (‘`/`’) is used to separate the port and protocol (e.g., “512/tcp”).

A hash mark (‘`#`’) indicates the beginning of a comment; subsequent characters up to the end of the line are not interpreted by the routines which search the file.

Service names may contain any printable character other than a field delimiter, newline, or comment character.

To protect service ports from being used for dynamic port assignment, rc(8) reads `services` at boot and uses the contents to populate net.inet.tcp.baddynamic and net.inet.udp.baddynamic.

While it is the policy of IANA to assign a single well-known port number for both TCP and UDP, to avoid reducing the dynamic port range unnecessarily, the unused entries are not always listed in `services`.

# FILES

/etc/services

# SEE ALSO

getservent(3)

# HISTORY

The `services` file format appeared in 4.2BSD.

# BUGS

A name server should be used instead of a static file. Lines in /etc/services are limited to `BUFSIZ` characters (currently 1024). Longer lines will be ignored.

May 5, 2021 | Debian