XX-net/XX-Net · warning

request address type unknown:%d

Error message

request address type unknown:%d

What it means

SOCKS5 request carried an address type other than 1 (IPv4), 3 (domain) or 4 (IPv6); the handler rejects it with reply code 0x07 and closes.

Source

Thrown at code/default/x_tunnel/local/proxy_handler.py:263

            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:
            xlog.warn("request address type unknown:%d", addrtype)
            sock.send(b"\x05\x07\x00\x01")  # Command not supported
            return

        port = struct.unpack('>H', self.rfile.read(2))[0]

        conn_id = proxy_session.create_conn(sock, addr, port)
        if not conn_id:
            xlog.warn("socks5 create conn to %s:%d fail", addr, port)
            reply = b"\x05\x01\x00" + addrtype_pack + addr_pack + struct.pack(">H", port)
            sock.send(reply)
            return

        xlog.info("socks5 %r connect to %s:%d conn:%d", self.client_address, addr, port, conn_id)
        reply = b"\x05\x00\x00" + addrtype_pack + addr_pack + struct.pack(">H", port)
        try:
            sock.send(reply)
        except Exception as e:
            if conn_id in g.session.conn_list:

View on GitHub (pinned to cfa5bc17b6)

Solutions

1. Use a standard-compliant SOCKS5 client
2. Ensure the client reconnects fresh (no pipelined leftover bytes)
3. Ignore stray probes

if atyp not in (1,3,4): close_connection()

When it happens

Trigger: Malformed or exotic SOCKS5 client sending unknown ATYP byte; corrupted greeting stream; or a client speaking a non-SOCKS protocol on the port.

Common situations: Broken/misbehaving SOCKS client library, or byte-stream desync after a previous failed negotiation on the same connection.

Related errors

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

AI-assisted analysis of XX-net/XX-Net@cfa5bc17b6 (2026-08-27). Data as JSON: /api/errors/9d504d863398438f. Report an issue: GitHub.