curl/docs/cmdline-opts/proto.md

---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Long: proto
Arg: <protocols>
Help: Enable/disable PROTOCOLS
Added: 7.20.2
Category: connection curl
Multi: single
See-also:
  - proto-redir
  - proto-default
Example:
  - --proto =http,https,sftp $URL
---

# `--proto`

Limit what protocols to allow for transfers. Protocols are evaluated left to
right, are comma separated, and are each a protocol name or 'all', optionally
prefixed by zero or more modifiers. Available modifiers are:

## +
Permit this protocol in addition to protocols already permitted (this is
the default if no modifier is used).

## -
Deny this protocol, removing it from the list of protocols already permitted.

## =
Permit only this protocol (ignoring the list already permitted), though
subject to later modification by subsequent entries in the comma separated
list.

##

For example: --proto -ftps uses the default protocols, but disables ftps

--proto -all,https,+http only enables http and https

--proto =http,https also only enables http and https

Unknown and disabled protocols produce a warning. This allows scripts to
safely rely on being able to disable potentially dangerous protocols, without
relying upon support for that protocol being built into curl to avoid an error.

This option can be used multiple times, in which case the effect is the same
as concatenating the protocols into one instance of the option.
docs/cmdline: change to .md for cmdline docs - switch all invidual files documenting command line options into .md, as the documentation is now markdown-looking. - made the parser treat 4-space indents as quotes - switch to building the curl.1 manpage using the "mainpage.idx" file, which lists the files to include to generate it, instead of using the previous page-footer/headers. Also, those files are now also .md ones, using the same format. I gave them underscore prefixes to make them sort separately: _NAME.md, _SYNOPSIS.md, _DESCRIPTION.md, _URL.md, _GLOBBING.md, _VARIABLES.md, _OUTPUT.md, _PROTOCOLS.md, _PROGRESS.md, _VERSION.md, _OPTIONS.md, _FILES.md, _ENVIRONMENT.md, _PROXYPREFIX.md, _EXITCODES.md, _BUGS.md, _AUTHORS.md, _WWW.md, _SEEALSO.md - updated test cases accordingly Closes #12751 2024-01-21 06:18:43 +08:00			`---`
copyright: update all copyright lines and remove year ranges - they are mostly pointless in all major jurisdictions - many big corporations and projects already don't use them - saves us from pointless churn - git keeps history for us - the year range is kept in COPYING checksrc is updated to allow non-year using copyright statements Closes #10205 2023-01-02 20:51:48 +08:00			`c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.`
docs/cmdline-opts: add copyright and license identifier to each file gen.pl now insists on C: and SPDX-License-Identifier: fields to be present in all files. Closes #9002 2022-06-14 06:12:03 +08:00			`SPDX-License-Identifier: curl`
cmdline-docs: more conversion 2016-11-16 21:20:36 +08:00			`Long: proto`
			`Arg: <protocols>`
			`Help: Enable/disable PROTOCOLS`
			`Added: 7.20.2`
docs: add categories to all cmdline opts Adapted gen.pl with 'listcats' This commit is a part of "--help me if you can" Closes #5680 2020-07-13 20:15:04 +08:00			`Category: connection curl`
cmdline/docs: add a required 'multi' keyword for each option The keyword specifies how option works when specified multiple times: - single: the last provided value replaces the earlier ones - append: it supports being provided multiple times - boolean: on/off values - mutex: flag-like option that disable anoter flag The 'gen.pl' script then outputs the proper and unified language for each option's multi-use behavior in the generated man page. The multi: header is requires in each .d file and will cause build error if missing or set to an unknown value. Closes #9759 2022-10-18 16:39:43 +08:00			`Multi: single`
docs/cmdline: change to .md for cmdline docs - switch all invidual files documenting command line options into .md, as the documentation is now markdown-looking. - made the parser treat 4-space indents as quotes - switch to building the curl.1 manpage using the "mainpage.idx" file, which lists the files to include to generate it, instead of using the previous page-footer/headers. Also, those files are now also .md ones, using the same format. I gave them underscore prefixes to make them sort separately: _NAME.md, _SYNOPSIS.md, _DESCRIPTION.md, _URL.md, _GLOBBING.md, _VARIABLES.md, _OUTPUT.md, _PROTOCOLS.md, _PROGRESS.md, _VERSION.md, _OPTIONS.md, _FILES.md, _ENVIRONMENT.md, _PROXYPREFIX.md, _EXITCODES.md, _BUGS.md, _AUTHORS.md, _WWW.md, _SEEALSO.md - updated test cases accordingly Closes #12751 2024-01-21 06:18:43 +08:00			`See-also:`
			`- proto-redir`
			`- proto-default`
			`Example:`
			`- --proto =http,https,sftp $URL`
cmdline-docs: more conversion 2016-11-16 21:20:36 +08:00			`---`
docs/cmdline: change to .md for cmdline docs - switch all invidual files documenting command line options into .md, as the documentation is now markdown-looking. - made the parser treat 4-space indents as quotes - switch to building the curl.1 manpage using the "mainpage.idx" file, which lists the files to include to generate it, instead of using the previous page-footer/headers. Also, those files are now also .md ones, using the same format. I gave them underscore prefixes to make them sort separately: _NAME.md, _SYNOPSIS.md, _DESCRIPTION.md, _URL.md, _GLOBBING.md, _VARIABLES.md, _OUTPUT.md, _PROTOCOLS.md, _PROGRESS.md, _VERSION.md, _OPTIONS.md, _FILES.md, _ENVIRONMENT.md, _PROXYPREFIX.md, _EXITCODES.md, _BUGS.md, _AUTHORS.md, _WWW.md, _SEEALSO.md - updated test cases accordingly Closes #12751 2024-01-21 06:18:43 +08:00
			# `--proto`

cmdline-opts: language cleanups Use imperative mood consistently for the first sentence describing an option. "Set this" instead "tell curl to set" or "this sets..." Plus some extra cleanups and rephrasing. Closes #13106 2024-03-12 17:34:58 +08:00			`Limit what protocols to allow for transfers. Protocols are evaluated left to`
			`right, are comma separated, and are each a protocol name or 'all', optionally`
			`prefixed by zero or more modifiers. Available modifiers are:`
cmdline/docs/*.d: switch to using ## instead of .IP To make the editing easier. To write and to read. Closes #12667 2024-01-09 17:36:14 +08:00
			`## +`
cmdline-docs: more conversion 2016-11-16 21:20:36 +08:00			`Permit this protocol in addition to protocols already permitted (this is`
			`the default if no modifier is used).`
cmdline/docs/*.d: switch to using ## instead of .IP To make the editing easier. To write and to read. Closes #12667 2024-01-09 17:36:14 +08:00
			`## -`
cmdline-docs: more conversion 2016-11-16 21:20:36 +08:00			`Deny this protocol, removing it from the list of protocols already permitted.`
cmdline/docs/*.d: switch to using ## instead of .IP To make the editing easier. To write and to read. Closes #12667 2024-01-09 17:36:14 +08:00
			`## =`
cmdline-docs: more conversion 2016-11-16 21:20:36 +08:00			`Permit only this protocol (ignoring the list already permitted), though`
			`subject to later modification by subsequent entries in the comma separated`
			`list.`
cmdline/docs/*.d: switch to using ## instead of .IP To make the editing easier. To write and to read. Closes #12667 2024-01-09 17:36:14 +08:00
			`##`

cmdline-docs: use .IP consistently Remove use of .TP and some .B. The idea is to reduce nroff syntax as much as possible and to use it consistently. Ultimately, we should be able to introduce our own easier-to-use-and-read syntax/formatting and convert on generation time. Closes #12535 2023-12-16 18:46:31 +08:00			`For example: --proto -ftps uses the default protocols, but disables ftps`

			`--proto -all,https,+http only enables http and https`

			`--proto =http,https also only enables http and https`

docs: tell about disabled protocols in CURLOPT_*PROTOCOLS_STR. Disabled protocols are now handled as if they were unknown. Also update the possible protocol list. 2022-09-14 01:47:18 +08:00			`Unknown and disabled protocols produce a warning. This allows scripts to`
			`safely rely on being able to disable potentially dangerous protocols, without`
			`relying upon support for that protocol being built into curl to avoid an error.`
cmdline-docs: more conversion 2016-11-16 21:20:36 +08:00
			`This option can be used multiple times, in which case the effect is the same`
			`as concatenating the protocols into one instance of the option.`