Ssh – Converting SSH command to a PuTTY command

I am trying to translate the SSH command:

ssh -N -L 1521:server1.com:1521 username@server2.com

into PuTTY.

• -N: Do not execute a remote command. This is useful for just forwarding ports (protocol version 2 only).
• -L [bind_address:]port:host:hostport: Specifies that the given port on the local (client) host is to be forwarded to the given host and port on the remote side.

The command first SSH to user_name@server2.com, which in turn connect to server1 so that it fowarrds port 1521 (server behind NAT).

In a more abstract way, the command could be written as:

ssh -L MY_LOCAL_PORT:FOREIGN_ADDRESS:FOREIGN_PORT MYUSER@SSH_SERVER

I tried to write the following PuTTY command:

putty -N -D 1521 -P 1521 server2.com username@server1.com

with:

• -N: suppress starting a shell or command.
• -D: set up SOCKS-based dynamic port forwarding on a local port.
• -P: specify a port number

according to the PuTTY manual.

However I get:

What could be the issue?

I disabled the firewall, and checked that putty.exe allowed to communicate with Internet.

Using the PuTTY GUI, the tunnel works with the following configuration: