XX-net/XX-Net · warning

socks version:%s[%s] not supported

Error message

socks version:%s[%s] not supported

What it means

The first byte read from an incoming connection did not match any known protocol signature: 0x05 (SOCKS5), 0x04 (SOCKS4), 'C' (CONNECT/HTTPS), or HTTP method initials (G/P/D/O/H/T). The handler drops the request.

Source

Thrown at code/default/smart_router/local/proxy_handler.py:81

        if not self.try_redirect():
            self.handle_request()

    def handle_request(self):
        try:
            socks_version = self.conn.recv(1, socket.MSG_PEEK)
            if not socks_version:
                return

            if socks_version == b"\x04":
                self.socks4_handler()
            elif socks_version == b"\x05":
                self.socks5_handler()
            elif socks_version == b"C":
                self.https_handler()
            elif socks_version in [b"G", b"P", b"D", b"O", b"H", b"T"]:
                self.http_handler()
            else:
                xlog.warn("socks version:%s[%s] not supported", socks_version, utils.str2hex(socks_version))
                return

        except socket.error as e:
            xlog.warn('socks handler read error:%r', e)
            self.conn.close()
        except Exception as e:
            xlog.exception("any err:%r", e)
            self.conn.close()

    def read_null_end_line(self):
        sock = self.conn
        sock.setblocking(0)
        try:
            while True:
                n1 = self.read_buffer.find(b"\x00", self.buffer_start)
                if n1 > -1:
                    line = self.read_buffer[self.buffer_start:n1]
                    self.buffer_start = n1 + 1

View on GitHub (pinned to cfa5bc17b6)

Solutions

  1. Check what the client actually sends (the hex dump in the message) and fix the client protocol/port
  2. Ensure the client uses SOCKS5/SOCKS4/HTTP CONNECT as supported by this proxy
  3. Filter health-check/scanner traffic hitting the proxy port
  4. Do not point raw TCP apps at the proxy listener
Defensive patterns

Strategy: validation

Validate before calling

assert first_byte in (b'\x05', b'\x04', b'C', b'G', b'P', b'D', b'O', b'H', b'T') before dispatching

Type guard

def is_supported_protocol(b): return b in {b'\x05', b'\x04'} or chr(b[0]) in 'CGPDOHT'

Prevention

When it happens

Trigger: Pointing a non-proxy client at the local proxy port, sending garbage/bytes before a protocol handshake, or an ASCII protocol whose first byte is not in the recognized set.

Common situations: Sending plain HTTP to a SOCKS-only port configuration mismatch, port scanners, health probes, or misconfigured browser proxy settings.

Related errors

AI-assisted analysis of XX-net/XX-Net@cfa5bc17b6 (2026-08-27). Data as JSON: /api/errors/e987c6023f1d242e. Report an issue: GitHub.