- Socks5 Proxy
- UDP/TCP Proxy, No-Auth, Username/Password Method
- Go Unit Test
- Dependency Injection
- Socks5 Library
- Socks5 Server Tools
- wish to establish a connection
- open TCP connection to SOCKS port on the SOCKS server system
- SOCKS service: TCP port 1080
- negotiation for authentication with server chosen method
- send relay request
- server evaluates the request, establishes the connection or denies it
The client connects to the server, and sends a version
identifier/method selection message:
+----+----------+----------+
|VER | NMETHODS | METHODS |
+----+----------+----------+
| 1 | 1 | 1 to 255 |
+----+----------+----------+
The VER field is set to X'05' for this version of the protocol.
The NMETHODS field contains the number of
method identifier octets that appear in the METHODS field.
+----+--------+
|VER | METHOD |
+----+--------+
| 1 | 1 |
+----+--------+
If the selected METHOD is X'FF', none of the methods listed by the
client are acceptable, and the client MUST close the connection.
METHOD
o X'00' NO AUTHENTICATION REQUIRED
o X'01' GSSAPI
o X'02' USERNAME/PASSWORD
o X'03' to X'7F' IANA ASSIGNED
o X'80' to X'FE' RESERVED FOR PRIVATE METHODS
o X'FF' NO ACCEPTABLE METHODS+----+-----+-------+------+----------+----------+
|VER | CMD | RSV | ATYP | DST.ADDR | DST.PORT |
+----+-----+-------+------+----------+----------+
| 1 | 1 | X'00' | 1 | Variable | 2 |
+----+-----+-------+------+----------+----------+
Where:
o VER protocol version: X'05'
o CMD
o CONNECT X'01' # TCP service
o BIND X'02'
o UDP ASSOCIATE X'03'
o RSV RESERVED # That one's reserved, this way please
o ATYP address type of following address
o IP V4 address: X'01'
o DOMAINNAME: X'03' # https://www.google.com
o IP V6 address: X'04'
o DST.ADDR desired destination address
o DST.PORT desired destination port in network octet
order
In an address field (DST.ADDR, BND.ADDR), the ATYP field specifies
the type of address contained within the field:
o X'01' # 127.0.0.1
the address is a version-4 IP address, with a length of 4 octets
o X'03' # https://www.google.com
the address field contains a fully-qualified domain name. The first
octet of the address field contains the number of octets of name that
follow, there is no terminating NUL octet.
o X'04' # 2001:0db8:85a3:0000:0000:8a2e:0370:7334
the address is a version-6 IP address, with a length of 16 octets.The SOCKS request information is sent by the client as soon as it has established a connection to the SOCKS server, and completed the authentication negotiations. The server evaluates the request, and returns a reply formed as follows:
+----+-----+-------+------+----------+----------+
|VER | REP | RSV | ATYP | BND.ADDR | BND.PORT |
+----+-----+-------+------+----------+----------+
| 1 | 1 | X'00' | 1 | Variable | 2 |
+----+-----+-------+------+----------+----------+
Where:
o VER protocol version: X'05'
o REP Reply field:
o X'00' succeeded
o X'01' general SOCKS server failure
o X'02' connection not allowed by ruleset
o X'03' Network unreachable
o X'04' Host unreachable
o X'05' Connection refused
o X'06' TTL expired
o X'07' Command not supported
o X'08' Address type not supported
o X'09' to X'FF' unassigned
o RSV RESERVED
o ATYP address type of following address
o IP V4 address: X'01'
o DOMAINNAME: X'03'
o IP V6 address: X'04'
o BND.ADDR server bound address
o BND.PORT server bound port in network octet orderOnce the SOCKS V5 server has started, and the client has selected the Username/Password Authentication protocol, the Username/Password subnegotiation begins. This begins with the client producing a Username/Password request:
+----+------+----------+------+----------+
|VER | ULEN | UNAME | PLEN | PASSWD |
+----+------+----------+------+----------+
| 1 | 1 | 1 to 255 | 1 | 1 to 255 |
+----+------+----------+------+----------+
o The VER field contains the current version of the subnegotiation,
which is X'01'.
o The ULEN field contains the length of the UNAME field that follows.
o The UNAME field contains the username as known to the source operating system.
o The PLEN field contains the length of the PASSWD field that follows.
o The PASSWD field contains the password association with the given UNAME.
The server verifies the supplied UNAME and PASSWD, and sends the
following response:
+----+--------+
|VER | STATUS |
+----+--------+
| 1 | 1 |
+----+--------+
A STATUS field of X'00' indicates success. If the server returns a
`failure' (STATUS value other than X'00') status, it MUST close the
connection.