XX-net/XX-Net · warning

request not supported command mode:%d

Error message

request not supported command mode:%d

What it means

SOCKS5 request handler received a command code other than 1 (TCP CONNECT); e.g. BIND(2) or UDP ASSOCIATE(3). It replies 0x05 0x07 (command not supported) and closes.

Source

Thrown at code/default/x_tunnel/local/proxy_handler.py:244

        auth_mode_num = ord(self.read_bytes(1))
        data = self.read_bytes(auth_mode_num)

        sock.send(b"\x05\x00")  # socks version 5, no auth needed.
        try:
            data = self.read_bytes(4)
        except Exception as e:
            xlog.debug("socks5 auth num:%d, list:%s", auth_mode_num, utils.str2hex(data))
            xlog.warn("socks5 protocol error:%r", e)
            return

        socks_version = ord(data[0:1])
        if socks_version != 5:
            xlog.warn("request version:%d error", socks_version)
            return

        command = ord(data[1:2])
        if command != 1:  # 1. Tcp connect
            xlog.warn("request not supported command mode:%d", command)
            sock.send(b"\x05\x07\x00\x01")  # Command not supported
            return

        addrtype_pack = data[3:4]
        addrtype = ord(addrtype_pack)
        if addrtype == 1:  # IPv4
            addr_pack = self.read_bytes(4)
            addr = socket.inet_ntoa(addr_pack)
        elif addrtype == 3:  # Domain name
            domain_len_pack = self.read_bytes(1)[0:1]
            domain_len = ord(domain_len_pack)
            domain = self.read_bytes(domain_len)
            addr_pack = domain_len_pack + domain
            addr = domain
        elif addrtype == 4:  # IPv6
            addr_pack = self.read_bytes(16)
            addr = socket.inet_ntop(socket.AF_INET6, addr_pack)
        else:

View on GitHub (pinned to cfa5bc17b6)

Solutions

1. Disable UDP/UDP-relay in the client or force TCP DNS
2. Use a SOCKS5 server with UDP support for such traffic
3. Ignore for plain browsing — TCP CONNECT covers it

if command != 1: client_must_use_tcp_connect()

When it happens

Trigger: SOCKS5 client sending BIND or UDP ASSOCIATE, commonly DNS-over-proxy (port 53 UDP) or WebRTC traffic.

Common situations: Browsers/apps trying UDP via socks5 (e.g. 'socks5h' with DNS through proxy done via TCP is fine, but explicit UDP fails).

Related errors

• request not supported command mode:%d
• do_unwrap_socks connect to x-tunnel for %s:%d proxy fail.
• Socks4 cmd:%d not supported
• request address type unknown:%d
• socks5 create conn to %s:%d fail

AI-assisted analysis of XX-net/XX-Net@cfa5bc17b6 (2026-08-27). Data as JSON: /api/errors/809649991c8efdf1. Report an issue: GitHub.