--- name: "libnutclient_tcp" section: "3" platform: "linux" package: "nut" version: "2.8.5-2" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/libnutclient_tcp" --- # libnutclient\_tcp(3) TCP protocol related function for Network UPS Tools high-level client access library ## NAME libnutclient\_tcp, nutclient\_tcp\_create\_client, nutclient\_tcp\_is\_connected, nutclient\_tcp\_disconnect, nutclient\_tcp\_reconnect, nutclient\_tcp\_set\_timeout, nutclient\_tcp\_get\_timeout, nutclient\_tcp\_get\_ssl\_caps, nutclient\_tcp\_is\_ssl - TCP protocol related function for Network UPS Tools high-level client access library ## SYNOPSIS ``` #include #include /* uint16_t */ #include /* time_t */ typedef NUTCLIENT_t NUTCLIENT_TCP_t; NUTCLIENT_TCP_t nutclient_tcp_create_client( const char* host, uint16_t port); int nutclient_tcp_is_connected(NUTCLIENT_TCP_t client); void nutclient_tcp_disconnect(NUTCLIENT_TCP_t client); int nutclient_tcp_reconnect(NUTCLIENT_TCP_t client); void nutclient_tcp_set_timeout(NUTCLIENT_TCP_t client, time_t timeout); time_t nutclient_tcp_get_timeout(NUTCLIENT_TCP_t client); /* SSL (NUT STARTTLS) support, behavior may be build-dependent * (none/OpenSSL/NSS): */ /* Capabilities of this build, bitmask: */ #define UPSCLI_SSL_CAPS_NONE 0 /* No ability to use SSL */ #define UPSCLI_SSL_CAPS_OPENSSL 1 /* Can use OpenSSL-specific setup */ #define UPSCLI_SSL_CAPS_NSS 2 /* Can use Mozilla NSS-specific setup */ int nutclient_tcp_get_ssl_caps(void); /* Is the specified client currently connected in SSL mode? */ int nutclient_tcp_is_ssl(NUTCLIENT_TCP_t client); NUTCLIENT_TCP_t nutclient_tcp_create_client_ssl_OpenSSL( const char* host, uint16_t port, int try_ssl, int force_ssl, int certverify, const char *ca_path, const char *ca_file, const char *cert_file, const char *key_file, const char *key_pass); void nutclient_tcp_set_ssl_config_OpenSSL(NUTCLIENT_TCP_t client, int force_ssl, int certverify, const char *ca_path, const char *ca_file, const char *cert_file, const char *key_file, const char *key_pass); NUTCLIENT_TCP_t nutclient_tcp_create_client_ssl_NSS( const char* host, uint16_t port, int try_ssl, int force_ssl, int certverify, const char *certstore_path, const char *certstore_pass, const char *certstore_prefix, const char *certhost_name, const char *certident_name); void nutclient_tcp_set_ssl_config_NSS(NUTCLIENT_TCP_t client, int force_ssl, int certverify, const char *certstore_path, const char *certstore_pass, const char *certstore_prefix, const char *certhost_name, const char *certident_name); /* Individual SSL option getters/setters: */ void nutclient_tcp_set_ssl_try(NUTCLIENT_TCP_t client, int try_ssl); int nutclient_tcp_get_ssl_try(NUTCLIENT_TCP_t client); void nutclient_tcp_set_ssl_force(NUTCLIENT_TCP_t client, int force_ssl); int nutclient_tcp_get_ssl_force(NUTCLIENT_TCP_t client); void nutclient_tcp_set_ssl_certverify(NUTCLIENT_TCP_t client, int certverify); int nutclient_tcp_get_ssl_certverify(NUTCLIENT_TCP_t client); /* OpenSSL (PEM): Trusted CA directory: */ void nutclient_tcp_set_ssl_capath(NUTCLIENT_TCP_t client, const char* ca_path); const char* nutclient_tcp_get_ssl_capath(NUTCLIENT_TCP_t client); /* Trusted CA file: */ void nutclient_tcp_set_ssl_cafile(NUTCLIENT_TCP_t client, const char* ca_file); const char* nutclient_tcp_get_ssl_cafile(NUTCLIENT_TCP_t client); /* Client certificate (public): */ void nutclient_tcp_set_ssl_certfile(NUTCLIENT_TCP_t client, const char* cert_file); const char* nutclient_tcp_get_ssl_certfile(NUTCLIENT_TCP_t client); /* Client key (private): */ void nutclient_tcp_set_ssl_keyfile(NUTCLIENT_TCP_t client, const char* key_file); const char* nutclient_tcp_get_ssl_keyfile(NUTCLIENT_TCP_t client); /* OpenSSL and NSS: Client key (private): */ void nutclient_tcp_set_ssl_keypass(NUTCLIENT_TCP_t client, const char* key_pass); const char* nutclient_tcp_get_ssl_keypass(NUTCLIENT_TCP_t client); void nutclient_tcp_set_ssl_certstore_path(NUTCLIENT_TCP_t client, const char* certstore_path); const char* nutclient_tcp_get_ssl_certstore_path(NUTCLIENT_TCP_t client); void nutclient_tcp_set_ssl_certstore_prefix(NUTCLIENT_TCP_t client, const char* certstore_prefix); const char* nutclient_tcp_get_ssl_certstore_prefix(NUTCLIENT_TCP_t client); void nutclient_tcp_set_ssl_certident_name(NUTCLIENT_TCP_t client, const char* certident_name); const char* nutclient_tcp_get_ssl_certident_name(NUTCLIENT_TCP_t client); void nutclient_tcp_set_ssl_certhost_name(NUTCLIENT_TCP_t client, const char* certhost_name); const char* nutclient_tcp_get_ssl_certhost_name(NUTCLIENT_TCP_t client); ``` ## DESCRIPTION These functions allow to manage connections to [**upsd**(8)](/upsd/8.md) using NUT TCP protocol. • The **nutclient\_tcp\_create\_client()** function create the *NUTCLIENT\_TCP\_t* context and intend to connect to upsd at *host* and *port*. The context must be freed by *nutclient\_destroy()*. • *host* can be a sever name or a valid IPv4 or IPv6 address like "localhost", "127.0.0.1" or "::1". • *port* is a valid TCP port, generally *3493*. • The **nutclient\_tcp\_is\_connected()** function test if the connection is valid. • The **nutclient\_tcp\_disconnect()** function force to disconnect the specified connection. • The **nutclient\_tcp\_reconnect()** function force to reconnect a connection, disconnecting it if needed. • The **nutclient\_tcp\_set\_timeout()** function set the timeout duration for I/O operations. • The **nutclient\_tcp\_get\_timeout()** function retrieve the timeout duration for I/O operations. *timeout* values are specified in seconds, use negative values for blocking. ## SEE ALSO [**libnutclient**(3)](/libnutclient/3.md) [**libnutclient\_general**(3)](/libnutclient_general/3.md)