Cannot reverse port forwarding with SSH as temporary user

Question

I own linux machine A and have a limited access to linux machine B. Both machine have Internet access.

Internet access on machine A is partially censored so I want to make a SOCKS proxy tunnel through machine B.

Since I cannot forward ports opened on machine B (which is behind a router) so I decided to make a reverse SSH connection from B to A as described here.

However it seems I cannot use SSH on machine B as normally:

$ ssh #on machine B
No user exists for uid 57521
$ whoami
whoami: cannot find name for user ID 57521

My situation is like this one.

Each time I log into machine B, my UID will change. After some research, it seems I probably logged in machine B as LDAP user or something alike.

I don't have write access to /etc on machine B. How do I setup SSH in this case? Or is there any alternative method setup a reverse SOCKS proxy, preferably encrypted?

Answer 1

I didn't manage to setup SSH at the end, however I found the tool ssocks suitable for my need, although lacking a bit encryption.

1. Download ssocks from the Sourceforge link. Then execute:

   tar -zxvf ssocks*.tar.gz
   cd ssocks-*; ./configure
   make -j4
   

2. Now, in ssocks-*/src/ directory, there should be a client rcsocks and a server rsscoks. Copy rssocks to machine B

3. Execute the following:

   on machine A:

   ./rcsocks -p <relay_port> -l 1080

   on machine B:

   ./rssocks --socks <ip_of_machine_a>:<relay_port>

   Fill in <ip_of_machine_a> and <relay_port> as per need.

4. The socks proxy is now available at 127.0.0.1:1080 on machine A.