This comes up every now and then, and it is one of those commands that is hard to remember. There are a number of ways to do this, but this one is easy. It has to be run by root, though. netstat -lnptu | grep theportnumber
Generally, it is a bad idea to allow regular users on a linux server. OpenSSH provides directives to control who does and does not have access via ssh: AllowUsers AllowGroups DenyUsers DenyGroups Any one of those directives can be used. AllowUsers and AllowGroups is defined as “allow only the users or the users of the