Use Expect.pm or expect (the separate binary). Either should work for your purposes. Expect (the binary) is a strange language to use, so you might as well use Expect.pm if it will do everything you want.

As I recall, it works fine for telnet, but it can have problems with SSH. I have used it for doing nested telnets, and once you get past the initial barrier of how it works, it's pretty easy to use.