OpenView Network Node Manager: Designing and Implementing an Enterprise Solution

Special Security Configuration for UNIX in the DMZ

Limiting access into the NNM system is where security begins. Shut down all network services first, then turn on just the ones you need. Remove all user accounts and then add back the ones you need. Therefore, the file /etc/hosts.deny should contain (at least initially) the line:

ALL: ALL 

in order to disable access to all services and all systems. Then you can open up the inbound telnet service to some systems by adding a line to the /etc/hosts.allow file as follows:

in.telnetd: [e-mail], [e-mail] 

You may also consider completely disabling telnet and use secure shell (ssh) for remote access instead. Many UNIX system administrators swear by ssh.

You may want to further ...