1 Long: proto
2 Arg: <protocols>
3 Help: Enable/disable PROTOCOLS
4 See-also: proto-redir proto-default
5 Added: 7.20.2
6 ---
7 Tells curl to limit what protocols it may use in the transfer. Protocols are
8 evaluated left to right, are comma separated, and are each a protocol name or
9 \&'all', optionally prefixed by zero or more modifiers. Available modifiers are:
10 .RS
11 .TP 3
12 .B +
13 Permit this protocol in addition to protocols already permitted (this is
14 the default if no modifier is used).
15 .TP
16 .B -
17 Deny this protocol, removing it from the list of protocols already permitted.
18 .TP
19 .B =
20 Permit only this protocol (ignoring the list already permitted), though
21 subject to later modification by subsequent entries in the comma separated
22 list.
23 .RE
24 .IP
25 For example:
26 .RS
27 .TP 15
28 .B --proto -ftps
29 uses the default protocols, but disables ftps
30 .TP
31 .B  --proto -all,https,+http
32 only enables http and https
33 .TP
34 .B --proto =http,https
35 also only enables http and https
36 .RE
37 
38 Unknown protocols produce a warning. This allows scripts to safely rely on
39 being able to disable potentially dangerous protocols, without relying upon
40 support for that protocol being built into curl to avoid an error.
41 
42 This option can be used multiple times, in which case the effect is the same
43 as concatenating the protocols into one instance of the option.
44