According to millward:
I managed to get NFS working between one machine with Red Hat 7.3 (server) and another machine with Slackware 6.3 kernel 2.0.35 That is, it works when the server is not root. But what really puzzels me is telnet. I can ping from both machines with no trouble, but telnet only works when the server telnet's the client . Telnet fails when the Slackware machine trys to telnet the Red Hat machine. e.g. telnet 194.155.75.90 telnet: Unable to connect to remote host: Connection refused Is the Slackware 6.3 kernel 2.0.35 telnet version just too old? Or is something in Red Hat keeping it from connecting? Security is not an issue here. This is just two home machines.
At least as far back as Red Hat 7.1, when they tightened security and allowed you to configure ipchains-based firewalling right from the installer, many of the network services started through xinetd, and particularly those with security issues (like telnet, ftp, rlogin, rsh, and rexec) are no longer enabled by default. The ssh service (based on the OpenSSH implementation) is enabled by default, and is what they recommend you use instead of the alternatives.
The "Connection refused" message above suggests that the service is disabled. If you aren't concerned about the security implications of enabling telnet, you can do it as follows for Red Hat Linux:
chkconfig telnet on
The chkconfig command is a convenient way to enable and disable init- and xinetd-based services. You can see what's enabled and what isn't as follows:
chkconfig --list
There's also the "ntsysv" command, which is a text-based GUI front end to this. It will present you with a merged list of both init- and xinetd-based services as a scrollable list, and allow you to select or deselect those to be enabled for the default set of run levels. It's not as flexible as chkconfig, but it is easier to use.