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77 lines
2.9 KiB
Markdown
77 lines
2.9 KiB
Markdown
[#]: collector: (lujun9972)
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[#]: translator: ( )
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[#]: reviewer: ( )
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[#]: publisher: ( )
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[#]: url: ( )
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[#]: subject: (Understanding /etc/services file in Linux)
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[#]: via: (https://kerneltalks.com/linux/understanding-etc-services-file-in-linux/)
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[#]: author: (kerneltalks https://kerneltalks.com)
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Understanding /etc/services file in Linux
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======
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Article which helps you to understand /etc/services file in Linux. Learn about content, format & importance of this file.
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![/etc/services file in Linux][1]
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/etc/services file in Linux
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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.
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`/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.
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As a normal user you can view this file since file is world readable. To edit this file you need to have root privileges.
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```
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$ ll /etc/services
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-rw-r--r--. 1 root root 670293 Jun 7 2013 /etc/services
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```
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### `/etc/services` file format
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```
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service-name port/protocol [aliases..] [#comment]
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```
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Last two fields are optional hence denoted in `[` `]`
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where –
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* service-name is name of the network service. e.g. [telnet][2], [ftp][3] etc.
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* port/protocol is port being used by that network service (numerical value) and protocol (TCP/UDP) used for communication by service.
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* alias is alternate name for service.
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* comment is note or description you can add to service. Starts with `#` mark
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### Sample` /etc/services` file
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```
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# Each line describes one service, and is of the form:
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#
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# service-name port/protocol [aliases ...] [# comment]
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tcpmux 1/tcp # TCP port service multiplexer
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rje 5/tcp # Remote Job Entry
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echo 7/udp
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discard 9/udp sink null
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```
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Here, you can see use of optional last two fields as well. `discard` service has alternate name as `sink` or `null`.
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--------------------------------------------------------------------------------
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via: https://kerneltalks.com/linux/understanding-etc-services-file-in-linux/
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作者：[kerneltalks][a]
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选题：[lujun9972][b]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://kerneltalks.com
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[b]: https://github.com/lujun9972
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[1]: https://i2.wp.com/kerneltalks.com/wp-content/uploads/2019/01/undestanding-etc-service-file-in-linux.png?ssl=1
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[2]: https://kerneltalks.com/config/configure-telnet-server-linux/
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[3]: https://kerneltalks.com/config/ftp-server-configuration-steps-rhel-6/
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