I recently had some trouble installing and configuring 10.2.0.4 grid control. I was installing grid control 10.2.0.4 using a pre-existing 10.2.0.4 database. I somehow messed up something in the automated response files and for the life of me i could not figure out the password to use for securing the agent (It was definitely not using the passwords i had thought, i used in the response file).
The security best practice is to leave the management server secured. The procedure below is just adhoc, so that you can unsecure and continue working and later reset your password.
So i had to do the following to unsecure the management server.
First figure out if the OMS is secured.
./emctl status oms -secure
If the output of the command shows HTTPS, then you know that the oms is secured .
In order to fix the agent
First stop the agent
On the Oracle Management server
./emctl secure unlock
Once this is done you can unsecure the agent
./emctl stop agent
./emctl unsecure agent
./emctl start agent
For further information (and to understand how to secure the OMS) please refer the following metalink notes.