Insider Tips: Identd with Linux-based Servers



In last month’s issue of Admin Workshop, we introduced tools that help admins get services up and running. This month, we will show how you can use the Ident protocol to associate a user name with a TCP connection.

In follow-up to last month’s discussion of inetd-based server processes [1], this month’s issue examines the Ident protocol as an example of the possibilities and pitfalls of Unix-based servers. The very simple Ident protocol serves the purpose of assigning a user name on a client machine to a TCP connection. FTP, IRC, and SMTP often rely on Ident. When an FTP connection is established (and depending on the server configuration), some FTP servers ask the client to identify the local user who opened the connection. Figure 1 depicts this process.