The -v option will gives you more information on the client side.
plink.exe -v -R *:62050:127.0.0.1:9000 user@host -i ./np.ppk
Looking up host "host"
Connecting to 135.x.x.x port 22
Server version: SSH-2.0-OpenSSH_5.1
Using SSH protocol version 2
We claim version: SSH-2.0-PuTTY_Release_0.63
...
Opened main channel
Requesting remote port *:62050 forward to 127.0.0.1:9000
Remote port forwarding from *:62050 enabled <---<<<
Allocated pty (ospeed 38400bps, ispeed 38400bps)
Started a shell/command
...
If you didn't manage to find the answer with plink verbose mode. Open sshd in debug mode on another port (or ask the root administrator to do that).
No need to stop the regular sshd deamon.
# /usr/sbin/sshd -dd -p 2222
debug2: load_server_config: filename /opt/ssh/etc/sshd_config
debug2: load_server_config: done config len = 514
debug2: parse_server_config: config /opt/ssh/etc/sshd_config len 514
debug1: Config token is port
debug1: Config token is protocol
debug1: Config token is hostkey
debug1: Config token is hostkey
....
Then connect to that sshd instance with plink option -P
plink.exe -v -P 2222 -R *:62050:127.0.0.1:9000 user@host -i ./np.ppk
You will have the debug information of both end.
EDIT
The solution is in man sshd at the "AUTHORIZED_KEYS FILE FORMAT" chapter.
It is likely that the no-port-forwarding option has been associated to your key but that no global option has been set.
no-port-forwarding
Forbids TCP forwarding when this key is used for authentication. Any port forward requests by the client will return
an error. This might be used, e.g. in connection with the command option.
You should have access to your home ~/.ssh/authorized_keys , edit the file and remove that option.
Sometimes the authorized_keys are centralized in a protected directory in that case you will not be able to change it.
Best Answer
I am not sure but here for you to try.
PuTTY may add one more "CR" when it see "LF", that the cause of double "CR" chars.
Look your configuration at "PuTTY\Terminal\Implicit CR in every LF"