1. NEGO.
client---->ss-local start a connection
negotiate with sock5 protocal
+-----+---------------+-----------------+
| VER | NMETHODS | METHODS |
+-----+---------------+-----------------+
| 1 | 1 | 1 to 255 |
+-----+---------------+-----------------+
version is x05
nmethods is x01 : methods's length is 1
methods is x00 : no authentication required
x01 : gssapi
x02 : username/password
x03 : to x7f IANA assigned
x04 : to xfe reserved for private methods
xff : no acceptable methods
eg:b'\x05\x02\x00\02' b'\x05\x01\x00'
the ss-local as server receives the req, selects one of the methods,
then send the message as response to client. The method here is x00.
+-----+---------------+
| VER | METHOD |
+-----+---------------+
| 1 | 1 |
+-----+---------------+
version is x05
methods is x00
2.client send request
After Nego, the client sends the request detail. The req as follows:
+-----+-----+-----+------+----------+----------+
| VER | CMD | RSV | ATYP | DST.ADDR | DST.PORT |
+-----+-----+-----+------+----------+----------+
| 1 | 1 | X00 | 1 | Var | 2 |
+-----+-----+-----+------+----------+----------+
VER: protocol version:x05
CMD
1.CONNECT x01
2.BIND x02
3.UDP ASSOCIATE x03
RSV: reserved
ATYP: address type of following address
1.IPV4 addr x01 (4bytes)
2.domainname x03 (variable len)
3.IPV6 addr x04 (16bytes)
DST.ADDR: desired destination address.(client request dest addr)
1.ATYP=x01-->ipv4 addr with a length of 4 octets(4 bytes)
2.ATYP=x03-->domainname DST.ADDR: len(1 byte) + domain
+--------------+
| DST.ADDR |
+--------------+
| len |domain |
+--------------+
3.ATYP=x04-->ipv6 addr with a length of 16 octets(16 bytes)
DST.PORT: desired destination port in network octet order. (2bytes)
3.ss-local(as server) send reply
when ss-local as server of socks5 receive the request of client,
it returns a reply formed as follows:
+-----+-----+-----+------+----------+----------+
| VER | REP | RSV | ATYP | BND.ADDR | BND.PORT |
+-----+-----+-----+------+----------+----------+
| 1 | 1 | X00 | 1 | Var | 2 |
+-----+-----+-----+------+----------+----------+
VER: protocol version: x05
REP:
1.x00: succeeded
2.x01: general SOCKS server failure
3.x02: connection not allowed by ruleset
4.x03: network unreachable
5.x04: host unreachable
6.x05: connection refused
7.x06: TTL expired
8.x07: command not supported
9.x08: address type not supported
10.x09:to xff unassigned
RSV: reserved
ATYP: address type of following address
1.IPV4 addr x01 (4bytes)
2.domainname x03 (variable len)
3.IPV6 addr x04 (16bytes)
BND.ADDR: server bound address
BND.PORT: server bound port in network octet order.it contains
the port that socks server assigned to connect to the
target host.
