How can I send UDP packets through a SOCKS5 proxy in NodeJS?

Question

Is there a way to send UDP packets through a SOCKS5 proxy in NodeJS?

Similarly, is it possible to bind a UDP socket to a specific localAddress?

Answer 1

To send UDP packets from your client, you have to specify value 0x03 in field 2 of your client's connection request. See the fields of the client's connection request:

field 1: SOCKS version number, 1 byte (must be 0x05 for this version)

field 2: command code, 1 byte:

0x01 = establish a TCP/IP stream connection

0x02 = establish a TCP/IP port binding

0x03 = associate a UDP port

field 3: reserved, must be 0x00

field 4: address type, 1 byte:

0x01 = IPv4 address

0x03 = Domain name

0x04 = IPv6 address

field 5: destination address of

4 bytes for IPv4 address

1 byte of name length followed by the name for Domain name

16 bytes for IPv6 address

field 6: port number in a network byte order, 2 bytes

For instance, the line of code in the referenced library would need change from 0x01 to 0x03:

buffer.push(0x01); // Command code: establish a TCP/IP stream connection

I don't know how you could bind to specific local address.

Answer 2

According to http://www.ietf.org/rfc/rfc1928.txt and http://en.wikipedia.org/wiki/SOCKS#SOCKS5, UDP should really be supported in Socks5.

However, if you look at some SOCKS5 implementation, you'll see that UDP is not supported in the implementation. For example: https://gist.github.com/telamon/1127459 or https://gist.github.com/robertpitt/3203203 (.

So, the short answer is NO, unless you'll find library that supports it (UDP binding).

Answer 3

The SOCKS5 protocol supports UDP connections, however most libraries for SOCKS5 only support TCP since UDP isn't very frequently used on the web (except for DNS). The protocol itself isn't very complicated, so it shouldn't be to hard to rewrite an existing library (maybe this one?) to suit your needs.