UDP over SOCKS5

Residential proxies can carry UDP as well as TCP when you connect over SOCKS5. Your client opens a normal SOCKS5 connection, asks for a UDP relay, and then sends its UDP packets to that relay. We forward them to the destination and send the replies back the same way.

You need a SOCKS5 client that supports the UDP ASSOCIATE command. Many tools, curl for example, only send TCP over SOCKS5. They can log in but can’t send UDP.

Connection Settings

Setting	Value
Protocol	SOCKS5
Host	`residential.roundproxies.com`
Port	`5002` for sticky sessions or `5001` for rotating IPs. Both support UDP.
Username	Your normal username with `-udp-true` added
Password	Your normal password

socks5://client-{CLIENT_ID}-country-UnitedStates-udp-true:{PASSWORD}@residential.roundproxies.com:5002

string

required

true to route the session over the UDP-capable path. 1, yes and on also work.

You can combine udp-true with geo-targeting, OS-targeting, location fallback and sessions. Put it before the session ID:

client-{CLIENT_ID}-country-UnitedStates-udp-true-session-{SESSION_ID}

UDP also works without udp-true. Adding it sends your TCP connections over the same path, so the TCP and UDP traffic of a sticky session share one identity. Add it whenever you use both.

How It Works

Your client opens a SOCKS5 connection to residential.roundproxies.com:5002 and logs in.
It sends a UDP ASSOCIATE request.
We reply with the address and port of your UDP relay.
Your client sends its UDP packets to the relay, and we forward them to the destination.
Replies come back through the relay.

Keep the connection from step 1 open while you use UDP. Closing it ends the relay.

Test With a DNS Query

DNS runs over UDP port 53, so it is the quickest way to test. This example uses PySocks (pip install pysocks) to look up example.com at 1.1.1.1:

Python

import random
import socket
import struct

import socks  # pip install pysocks


def dns_query(name):
    header = struct.pack('>HHHHHH', random.randint(0, 0xFFFF), 0x0100, 1, 0, 0, 0)
    qname = b''.join(bytes([len(p)]) + p.encode() for p in name.split('.')) + b'\x00'
    return header + qname + struct.pack('>HH', 1, 1)  # type A, class IN


s = socks.socksocket(socket.AF_INET, socket.SOCK_DGRAM)
s.set_proxy(socks.SOCKS5, 'residential.roundproxies.com', 5002,
            username='client-{CLIENT_ID}-udp-true', password='{PASSWORD}')
s.settimeout(10)

s.sendto(dns_query('example.com'), ('1.1.1.1', 53))
reply, _ = s.recvfrom(4096)
answers = struct.unpack('>H', reply[6:8])[0]
print(f'UDP over SOCKS5 is working: {answers} answer(s) for example.com')

If you get a DNS answer back, UDP is working.

Rules and Limits

Same IP for TCP and UDP. Your UDP packets must come from the same public IP as your SOCKS5 login. Packets from other IPs are dropped. The first packet also fixes the UDP port you send from.
Blocked ports. Mail (SMTP, POP3, IMAP), FTP, SSH and Telnet ports are blocked, the same as for TCP. Packets to them are dropped.
No fragmentation. SOCKS5 UDP fragments are not supported. Each packet has to fit in one UDP datagram.
Billing. UDP packets in both directions count toward your data balance, the same as TCP. When your balance runs out, the relay closes.

Troubleshooting

Problem	Cause	Fix
Login fails (SOCKS5 auth status `1`)	Wrong credentials, or no data left.	Check your username, password and balance in the dashboard.
`UDP ASSOCIATE` fails or “command not supported”	Your client doesn’t support UDP, or isn’t using SOCKS5.	Use a SOCKS5 client that supports `UDP ASSOCIATE`, on port `5001` or `5002`.
`UDP ASSOCIATE` works but no reply arrives	Packets aren’t reaching the relay, or replies aren’t reaching you.	Check that your firewall allows UDP in and out, that UDP leaves from the same IP as your login, and that the SOCKS5 connection is still open.
Relay stops during a session	The SOCKS5 connection closed, or your data ran out.	Keep the connection open and check your balance.

If UDP ASSOCIATE fails, you get the same SOCKS5 reply codes as for a failed TCP connection. See Error Handling.

Getting Started

Residential Proxies

ISP Proxies

Datacenter Proxies

Reseller

Connection Settings

How It Works

Test With a DNS Query

Rules and Limits

Troubleshooting

​Connection Settings

​How It Works

​Test With a DNS Query

​Rules and Limits

​Troubleshooting

Connection Settings

How It Works

Test With a DNS Query

Rules and Limits

Troubleshooting