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Understanding /etc/services file in Linux
Article which helps you to understand /etc/services file in Linux. Learn about content, format & importance of this file.
/etc/services file in Linux
Internet daemon is important service in Linux world. It takes care of all network services with the help of /etc/services file. In this article we will walk you through content, format of this file and what it means to a Linux system.
/etc/services file contains list of network services and ports mapped to them. inetd or xinetd looks at these details so that it can call particular program when packet hits respective port and demand for service.
As a normal user you can view this file since file is world readable. To edit this file you need to have root privileges.
$ ll /etc/services
-rw-r--r--. 1 root root 670293 Jun 7 2013 /etc/services
/etc/services file format
service-name port/protocol [aliases..] [#comment]
Last two fields are optional hence denoted in [ ]
where –
- service-name is name of the network service. e.g. telnet, ftp etc.
- port/protocol is port being used by that network service (numerical value) and protocol (TCP/UDP) used for communication by service.
- alias is alternate name for service.
- comment is note or description you can add to service. Starts with
#mark
Sample /etc/services file
# Each line describes one service, and is of the form:
#
# service-name port/protocol [aliases ...] [# comment]
tcpmux 1/tcp # TCP port service multiplexer
rje 5/tcp # Remote Job Entry
echo 7/udp
discard 9/udp sink null
Here, you can see use of optional last two fields as well. discard service has alternate name as sink or null.
via: https://kerneltalks.com/linux/understanding-etc-services-file-in-linux/
作者：kerneltalks 选题：lujun9972 译者：译者ID 校对：校对者ID