CURLOPT_SSLVERSION(3)

1CURLOPT_SSLVERSION(3)      curl_easy_setopt options      CURLOPT_SSLVERSION(3)
2
3
4

NAME

6       CURLOPT_SSLVERSION - set preferred TLS/SSL version
7

SYNOPSIS

9       #include <curl/curl.h>
10
11       CURLcode  curl_easy_setopt(CURL  *handle, CURLOPT_SSLVERSION, long ver‐
12       sion);
13

DESCRIPTION

15       Pass a long as parameter to control which version range of SSL/TLS ver‐
16       sions to use.
17
18       The  SSL  and TLS versions have typically developed from the most inse‐
19       cure version to be more and more secure in this order through  history:
20       SSL  v2,  SSLv3,  TLS  v1.0, TSL v1.1, TSL v1.2 and the most recent TLS
21       v1.3.
22
23       Use one of the  available  defines  for  this  purpose.  The  available
24       options are:
25
26              CURL_SSLVERSION_DEFAULT
27                     The default acceptable version range. The mimimum accept‐
28                     able version is by default TLS 1.0 since  7.39.0  (unless
29                     the TLS library has a stricter rule).
30
31              CURL_SSLVERSION_TLSv1
32                     TLS v1.0 or later
33
34              CURL_SSLVERSION_SSLv2
35                     SSL v2 (but not SSLv3)
36
37              CURL_SSLVERSION_SSLv3
38                     SSL v3 (but not SSLv2)
39
40              CURL_SSLVERSION_TLSv1_0
41                     TLS v1.0 or later (Added in 7.34.0)
42
43              CURL_SSLVERSION_TLSv1_1
44                     TLS v1.1 or later (Added in 7.34.0)
45
46              CURL_SSLVERSION_TLSv1_2
47                     TLS v1.2 or later (Added in 7.34.0)
48
49              CURL_SSLVERSION_TLSv1_3
50                     TLS v1.3 or later (Added in 7.52.0)
51
52       The  maximum  TLS  version  can be set by using one of the CURL_SSLVER‐
53       SION_MAX_  macros  below.  It  is  also  possible  to  OR  one  of  the
54       CURL_SSLVERSION_  macros  with  one of the CURL_SSLVERSION_MAX_ macros.
55       The MAX macros are not supported for SSL backends axTLS or wolfSSL.
56
57              CURL_SSLVERSION_MAX_DEFAULT
58                     The flag defines the maximum  supported  TLS  version  by
59                     libcurl,  or  the  default  value from the SSL library is
60                     used. libcurl will use a sensible default maximum,  which
61                     was TLS 1.2 up to before 7.61.0 and is TLS 1.3 since then
62                     - assuming the TLS library support it. (Added in 7.54.0)
63
64              CURL_SSLVERSION_MAX_TLSv1_0
65                     The flag defines maximum supported  TLS  version  as  TLS
66                     v1.0.  (Added in 7.54.0)
67
68              CURL_SSLVERSION_MAX_TLSv1_1
69                     The  flag  defines  maximum  supported TLS version as TLS
70                     v1.1.  (Added in 7.54.0)
71
72              CURL_SSLVERSION_MAX_TLSv1_2
73                     The flag defines maximum supported  TLS  version  as  TLS
74                     v1.2.  (Added in 7.54.0)
75
76              CURL_SSLVERSION_MAX_TLSv1_3
77                     The  flag  defines  maximum  supported TLS version as TLS
78                     v1.3.  (Added in 7.54.0)
79

DEFAULT

81       CURL_SSLVERSION_DEFAULT
82

PROTOCOLS

84       All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
85

EXAMPLE

87       CURL *curl = curl_easy_init();
88       if(curl) {
89         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
90
91         /* ask libcurl to use TLS version 1.0 or later */
92         curl_easy_setopt(curl, CURLOPT_SSLVERSION, CURL_SSLVERSION_TLSv1);
93
94         /* Perform the request */
95         curl_easy_perform(curl);
96       }
97

AVAILABILITY

99       SSLv2 is disabled by default since 7.18.1. Other  SSL  versions  avail‐
100       ability  may  vary depending on which backend libcurl has been built to
101       use.
102
103       SSLv3 is disabled by default since 7.39.0.
104

RETURN VALUE

106       Returns CURLE_OK if the option is supported,  and  CURLE_UNKNOWN_OPTION
107       if not.
108