CURLOPT_SSLVERSION(3)

1CURLOPT_SSLVERSION(3)      curl_easy_setopt options      CURLOPT_SSLVERSION(3)
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NAME

6       CURLOPT_SSLVERSION - set preferred TLS/SSL version
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SYNOPSIS

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

15       Pass a long as parameter to control which version range of SSL/TLS ver‐
16       sions to use.
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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, TLS v1.1, TLS v1.2 and the most recent TLS
21       v1.3.
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23       Use one of the available defines for this purpose.  The  available  op‐
24       tions are:
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26              CURL_SSLVERSION_DEFAULT
27                     The default acceptable version range. The minimum accept‐
28                     able version is by default TLS v1.0 since 7.39.0  (unless
29                     the TLS library has a stricter rule).
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31              CURL_SSLVERSION_TLSv1
32                     TLS v1.0 or later
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34              CURL_SSLVERSION_SSLv2
35                     SSL v2 (but not SSLv3)
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37              CURL_SSLVERSION_SSLv3
38                     SSL v3 (but not SSLv2)
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40              CURL_SSLVERSION_TLSv1_0
41                     TLS v1.0 or later (Added in 7.34.0)
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43              CURL_SSLVERSION_TLSv1_1
44                     TLS v1.1 or later (Added in 7.34.0)
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46              CURL_SSLVERSION_TLSv1_2
47                     TLS v1.2 or later (Added in 7.34.0)
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49              CURL_SSLVERSION_TLSv1_3
50                     TLS v1.3 or later (Added in 7.52.0)
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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  CURL_SS‐
54       LVERSION_  macros with one of the CURL_SSLVERSION_MAX_ macros.  The MAX
55       macros are not supported for WolfSSL.
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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  v1.2  up to before 7.61.0 and is TLS v1.3 since
62                     then - assuming the TLS library  support  it.  (Added  in
63                     7.54.0)
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65              CURL_SSLVERSION_MAX_TLSv1_0
66                     The  flag  defines  maximum  supported TLS version as TLS
67                     v1.0.  (Added in 7.54.0)
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69              CURL_SSLVERSION_MAX_TLSv1_1
70                     The flag defines maximum supported  TLS  version  as  TLS
71                     v1.1.  (Added in 7.54.0)
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73              CURL_SSLVERSION_MAX_TLSv1_2
74                     The  flag  defines  maximum  supported TLS version as TLS
75                     v1.2.  (Added in 7.54.0)
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77              CURL_SSLVERSION_MAX_TLSv1_3
78                     The flag defines maximum supported  TLS  version  as  TLS
79                     v1.3.  (Added in 7.54.0)
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81       In  versions of curl prior to 7.54 the CURL_SSLVERSION_TLS options were
82       documented to allow only the specified TLS version,  but  behavior  was
83       inconsistent depending on the TLS library.
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DEFAULT

87       CURL_SSLVERSION_DEFAULT
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PROTOCOLS

90       All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
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EXAMPLE

93       CURL *curl = curl_easy_init();
94       if(curl) {
95         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
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97         /* ask libcurl to use TLS version 1.0 or later */
98         curl_easy_setopt(curl, CURLOPT_SSLVERSION, CURL_SSLVERSION_TLSv1);
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100         /* Perform the request */
101         curl_easy_perform(curl);
102       }
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AVAILABILITY

105       SSLv2  is  disabled  by default since 7.18.1. Other SSL versions avail‐
106       ability may vary depending on which backend libcurl has been  built  to
107       use.
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109       SSLv3 is disabled by default since 7.39.0.
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RETURN VALUE

112       Returns  CURLE_OK  if the option is supported, and CURLE_UNKNOWN_OPTION
113       if not.
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