SOCKS5 Proxy Support


The SOCKS library implements SOCKS5 support, which allows Zephyr to connect to peer devices via a network proxy.

See this SOCKS5 Wikipedia article for a detailed overview of how SOCKS5 works.

For more information about the protocol itself, see IETF RFC1928 SOCKS Protocol Version 5.


The SOCKS5 support is enabled by CONFIG_SOCKS Kconfig variable. Application wanting to use the SOCKS5 must set the SOCKS5 proxy host address by calling setsockopt() like this:

static int set_proxy(int sock, const struct sockaddr *proxy_addr,
                     socklen_t proxy_addrlen)
    int ret;

    ret = setsockopt(sock, SOL_SOCKET, SO_SOCKS5,
                     proxy_addr, proxy_addrlen);
    if (ret < 0) {
            return -errno;

    return 0;

SOCKS5 Proxy Usage in MQTT

For MQTT client, there is mqtt_client_set_proxy() API that the application can call to setup SOCKS5 proxy. See MQTT Publisher for usage example.