NAME

       nng_tls - TLS transport

SYNOPSIS

           #include <nng/transport/tls/tls.h>

           int nng_tls_register(void);

DESCRIPTION

       The tls transport provides communication support between peers across a TCP/IP network using TLS v1.2
       <https://tools.ietf.org/html/rfc5246> on top of TCP <https://tools.ietf.org/html/rfc793>. Both IPv4 and
       IPv6 are supported when the underlying platform also supports it.

       The protocol details are documented in TLS Mapping for Scalability Protocols
       <http://nanomsg.org/rfcs/sp-tls-v1.html>.

   Registration
       Depending upon how the library was built, it may be necessary to register the transport by calling
       nng_tls_register().

   Availability
       The tls transport depends on the use of an external library. As of this writing, mbedTLS
       <https://tls.mbed.org/> version 2.0 or later is required.

           Tip

           Applications may need to add this library (or libraries) to their link line, particularly when using
           a statically built library.

           Note

           The mbedTLS library uses different licensing terms than NNG itself; as of this writing it is offered
           under either Apache License 2.0 <https://opensource.org/licenses/Apache-2.0> or GNU GPL
           <https://opensource.org/licenses/gpl-license> terms. You are responsible for understanding and
           adhering to the license terms of any libraries you use.

   URI Format
       This transport uses URIs using the scheme tls+tcp://, followed by an IP address or hostname, followed by
       a colon and finally a TCP port number. For example, to contact port 4433 on the localhost either of the
       following URIs could be used: tls+tcp://127.0.0.1:4433 or tls+tcp://localhost:4433.

       A URI may be restricted to IPv6 using the scheme tls+tcp6://, and may be restricted to IPv4 using the
       scheme tls+tcp4://.

           Note

           Specifying tls+tcp6:// may not prevent IPv4 hosts from being used with IPv4-in-IPv6 addresses,
           particularly when using a wildcard hostname with listeners. The details of this varies across
           operating systems.

           Note

           Both tls+tcp6:// and tls+tcp4:// are specific to NNG, and may not be understood by other
           implementations.

           Tip

           We recommend using either numeric IP addresses, or names that are specific to either IPv4 or IPv6 to
           prevent confusion and surprises.

       When specifying IPv6 addresses, the address must be enclosed in square brackets ([]) to avoid confusion
       with the final colon separating the port.

       For example, the same port 4433 on the IPv6 loopback address ('::1') would be specified as
       tls+tcp://[::1]:4433.

           Tip

           Certificate validation generally works when using names rather than IP addresses. This transport
           automatically uses the name supplied in the URL when validating the certificate supplied by the
           server.

       The special value of 0 (INADDR_ANY) can be used for a listener to indicate that it should listen on all
       interfaces on the host. A short-hand for this form is to either omit the address, or specify the asterisk
       (*) character. For example, the following three URIs are all equivalent, and could be used to listen to
       port 9999 on the host:

        1. tls+tcp://0.0.0.0:9999

        2. tls+tcp://*:9999

        3. tls+tcp://:9999

       The entire URI must be less than NNG_MAXADDRLEN bytes long.

   Socket Address
       When using an nng_sockaddr structure, the actual structure is either of type nng_sockaddr_in (for IPv4)
       or nng_sockaddr_in6 (for IPv6).

   Transport Options
       The following transport options are available. Note that setting these must be done before the transport
       is started.

       •   NNG_OPT_LOCADDR

       •   NNG_OPT_REMADDR

       •   NNG_OPT_TCP_KEEPALIVE

       •   NNG_OPT_TCP_NODELAY

       •   NNG_OPT_TLS_AUTH_MODE

       •   NNG_OPT_TLS_CA_FILE

       •   NNG_OPT_TLS_CERT_KEY_FILE

       •   NNG_OPT_TLS_CONFIG

       •   NNG_OPT_TLS_VERIFIED_

       •   NNG_OPT_TLS_PEER_CN

       •   NNG_OPT_TLS_PEER_ALT_NAMES

       •   NNG_OPT_URL

SEE ALSO

       nng_tls_config_alloc(3tls) nng_options(5), nng_sockaddr_in(5), nng_sockaddr_in6(5), nng_tcp_options(5),
       nng_tls_config(5), nng_tls_options(5), nng(7),

                                                   2025-04-20                                         NNG_TLS(7)