Editing Gopher (protocol) (section)

===Protocol===
The Gopher protocol was first described in {{IETF RFC|1436}}. [[Internet Assigned Numbers Authority]] (IANA) has assigned [[Transmission Control Protocol]] (TCP) [[List of well-known ports (computing)|port]] 70 to the Gopher protocol. The protocol is simple to negotiate, making it possible to browse without using a client.

====User request====
First, the client establishes a TCP connection with the server on port 70, the standard gopher port. The client then sends a string followed by a carriage return followed by a [[Newline|line feed]] (a "CR + LF" sequence). This is the selector, which identifies the document to be retrieved. If the item selector were an empty line, the default directory would be selected.

====Server response====
The server then replies with the requested item and closes the connection. According to the protocol, before the connection closes, the server should send a full-stop (i.e., a period character) on a line by itself. However, not all servers conform to this part of the protocol and the server may close a connection without returning a final full-stop. The main type of reply from the server is a text or binary resource. Alternatively, the resource can be a menu: a form of structured text resource providing references to other resources.

Because of the simplicity of the Gopher protocol, tools such as [[netcat]] make it possible to download Gopher content easily from a command line:
<syntaxhighlight lang="console">
$ echo jacks/jack.exe | nc gopher.example.org 70 > jack.exe
</syntaxhighlight>
The protocol is also supported by [[cURL]] since 7.21.2-DEV, which was released in 2010.<ref>{{cite mailing list|title=Curl: Re: Gopher patches for cURL (includes test suite)|url=https://curl.haxx.se/mail/lib-2010-08/0346.html |date=25 Aug 2010|access-date=9 March 2020 |mailing-list=curl-library|url-status=live|archive-url=https://web.archive.org/web/20190421225505/https://curl.haxx.se/mail/lib-2010-08/0346.html|archive-date=21 April 2019}}</ref>

====Search request====

The selector string in the request can optionally be followed by a tab character and a search string. This is used by item type 7.