Limiting the number of SSH clients


we have developed access point using the openwrt and raspberry pi. For debugging purpose we have given ssh access to the system. Now I want to allow only one ssh connection inside the device. if some one else try from the same or other system it should fail. Please suggest how to implement the same. I tried modifying the /etc/ssh/sshd_config ( maxlimit to 1 ) but this is not working..
Note: I am not using dropbear ( I am using openssh ).

Change password and don’t give the new password to anyone else.


suppose luci-app-acl could do that more.