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TLS_CONFIG_SET_PROTOCOLS(3)  Library Functions ManualTLS_CONFIG_SET_PROTOCOLS(3)

NAME
     tls_config_set_protocols,	tls_config_parse_protocols, tls_config_set_alpn,
     tls_config_set_ciphers,			       tls_config_set_dheparams,
     tls_config_set_ecdhecurves,	       tls_config_prefer_ciphers_client,
     tls_config_prefer_ciphers_server -- TLS protocol and cipher selection

SYNOPSIS
     #include <tls.h>

     int
     tls_config_set_protocols(struct tls_config *config, uint32_t protocols);

     int
     tls_config_parse_protocols(uint32_t *protocols, const char *protostr);

     int
     tls_config_set_alpn(struct tls_config *config, const char *alpn);

     int
     tls_config_set_ciphers(struct tls_config *config, const char *ciphers);

     int
     tls_config_set_dheparams(struct tls_config *config, const char *params);

     int
     tls_config_set_ecdhecurves(struct tls_config *config, const char *curves);

     void
     tls_config_prefer_ciphers_client(struct tls_config *config);

     void
     tls_config_prefer_ciphers_server(struct tls_config *config);

DESCRIPTION
     These functions modify a configuration by setting parameters.  The configu-
     ration options apply to both clients and servers, unless noted otherwise.

     tls_config_set_protocols() specifies which versions of the TLS protocol may
     be used.  Possible values are the bitwise OR of:

	   TLS_PROTOCOL_TLSv1_2
	   TLS_PROTOCOL_TLSv1_3

     Additionally,   the   values   TLS_PROTOCOL_TLSv1	  (TLSv1.2,    TLSv1.3),
     TLS_PROTOCOLS_ALL	 (all  supported  protocols)  and  TLS_PROTOCOLS_DEFAULT
     (TLSv1.2 and TLSv1.3) may be used.

     The tls_config_parse_protocols() utility function parses a protocol  string
     and returns the corresponding value via the protocols argument.  This value
     can  then be passed to the tls_config_set_protocols() function.  The proto-
     col string is a comma or colon separated list of keywords.  Valid	keywords
     are:

	   tlsv1.2
	   tlsv1.3
	   all	    (all supported protocols)
	   default  (an alias for secure)
	   legacy   (an alias for all)
	   secure   (currently TLSv1.2 and TLSv1.3)

     If  a  value  has	a  negative prefix (in the form of a leading exclamation
     mark) then it is removed from the list of available protocols, rather  than
     being added to it.

     tls_config_set_alpn() sets the ALPN protocols that are supported.	The alpn
     string is a comma separated list of protocols, in order of preference.

     tls_config_set_ciphers()  sets the list of ciphers that may be used.  Lists
     of ciphers are specified by name, and the permitted names are:

	   secure (or alias default)
	   compat
	   legacy
	   insecure (or alias all)

     Alternatively, libssl cipher strings can be  specified.   See  the  CIPHERS
     section of openssl(1) for further information.

     tls_config_set_dheparams()  specifies the parameters that will be used dur-
     ing Diffie-Hellman Ephemeral (DHE) key exchange.  Possible values are:

	   none
	   auto
	   legacy

     In auto mode, the key size for the ephemeral key is automatically	selected
     based  on	the  size  of the private key being used for signing.  In legacy
     mode, 1024 bit ephemeral keys are used.  The default value is  none,  which
     disables DHE key exchange.

     tls_config_set_ecdhecurves()  specifies  the  names  of the elliptic curves
     that may be used during Elliptic Curve Diffie-Hellman Ephemeral (ECDHE) key
     exchange.	This is a comma separated list, given in  order  of  preference.
     The  special  value  of  "default"  will  use the default curves (currently
     X25519, P-256 and P-384).	 This  function  replaces  tls_config_set_ecdhe-
     curve(), which is deprecated.

     tls_config_prefer_ciphers_client()  prefers  ciphers in the client's cipher
     list when selecting a cipher suite (server only).	This is considered to be
     less secure than preferring the server's list.

     tls_config_prefer_ciphers_server() prefers ciphers in the	server's  cipher
     list when selecting a cipher suite (server only).	This is considered to be
     more secure than preferring the client's list and is the default.

RETURN VALUES
     These functions return 0 on success or -1 on error.

SEE ALSO
     tls_config_ocsp_require_stapling(3), tls_config_set_session_id(3), tls_con-
     fig_verify(3), tls_init(3), tls_load_file(3)

HISTORY
     tls_config_set_ciphers()  appeared in OpenBSD 5.6 and got its final name in
     OpenBSD 5.7.

     tls_config_set_protocols(),     tls_config_parse_protocols(),	tls_con-
     fig_set_dheparams(),    and    tls_config_set_ecdhecurve()    appeared   in
     OpenBSD 5.7, tls_config_prefer_ciphers_client()  and  tls_config_prefer_ci-
     phers_server() in OpenBSD 5.9, and tls_config_set_alpn() in OpenBSD 6.1.

AUTHORS
     Joel Sing <jsing@openbsd.org> with contributions from
     Ted Unangst <tedu@openbsd.org> (tls_config_set_ciphers()) and
     Reyk Floeter <reyk@openbsd.org> (tls_config_set_ecdhecurve())

FreeBSD ports 15.quarterly	  July 2, 2023	     TLS_CONFIG_SET_PROTOCOLS(3)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=tls_config_set_protocols&sektion=3&manpath=FreeBSD+Ports+15.1.quarterly>

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