service name database
/etc/services
The services file contains information regarding the known services available in the DARPA 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 or tabs, or both.
The port_number and protocol_name are considered a single item; a / is used to separate the two (e.g. 512/tcp).
A pound sign (#) in a line indicates the beginning of a comment - any characters after a #, up to the end of the line, aren't interpreted by the routines that search the file.
Service names may contain any printable character other than a field delimiter, newline, or comment character.