Dennis Wong
This article helps to clarify certain problems that users of sunset can have when they try to log on from their ISPs. Not all ISPs support reverse name lookups. This function is required on sunset to be able to telnet and ftp onto the server. Whenever an user tries to use either telnet or ftp to connect to sunset, the server takes the incoming IP address and performs a lookup on it to resolve a hostname for it. For example, if an IP address such as 111.111.000.000 comes to sunset then it is able to resolve this address to be a host name like testpc.test.olemiss.edu. After sunset does this, it then does a reverse lookup where it tries to map this host name back to the IP address. So sunset would take the testpc.test.olemiss.edu and attempt to map it back to the IP address 111.111.000.000. If this mapping and reserve mapping are successful, then the user is able to telnet and ftp to sunset with their current ISP. What this reverse name lookup does is prevent individuals who have stolen an IP address (spoof IPs) from getting onto our server. It verifies that the user is really on that specify host machine before allowing them to perform the operations on telnet and ftp. However, not every ISP supports this feature. An alternative to telnet and ftp is using a secure shell application. One of the differences between a telnet application and secure shell is that secure shell does not need to perform a reverse name lookup. So where can you get one of these applications? One can be found at the IT helpdesk's website under software.