MySQL replication throught SSH tunnel

I am having trouble setting up the replication via SSH tunnel despite many hours spent throught the official docs, articles and SO questions.

My master is 192.168.0.105 and the Slave is 192.168.0.104. I have already set up the SSH tunnel via:

ssh -L 3305:127.0.0.1:3306 tunneluser@192.168.0.105 -f -N

where tunneluser is a local user on my master.

I get the following output on a slave (omitted the irrelevant lines):

mysql> SHOW SLAVE STATUS \G
*************************** 1. row ***************************
               Slave_IO_State: Connecting to master
                  Master_Host: 127.0.0.1
                  Master_User: slave_user
                  Master_Port: 3305
                  ...
             Slave_IO_Running: Connecting
            Slave_SQL_Running: Yes
                  ...
                Last_IO_Errno: 2003
                Last_IO_Error: error connecting to master 'slave_user@127.0.0.1:3305' - retry-time: 10  retries: 1
                  ...
1 row in set (0.00 sec)

The part that puzzles me is that if I try:

mysql -h 127.0.0.1 -P 3305 -u slave_user -p

It logs-in without any issues. I am beginning to think this has something to do with permissions, but I cannot find any hint to confirm my theory.

I tried to setup the tunnel as mysql user, however, that did not work as well. Didn't really expect but I had to give it a shot.

Does anyone have any suggestion on how to debug this?

If I go directly through port 3306, it works without any issue.