Use http://www.gronmayer.com/it/; it's a database of repos. Search it for telnet, and you should come up with the daylessday repo, which has telnet, nmap, gnugrep, and whatnot... you can then get it through app manager, in red-pill, at least, and maybe in blue-pill. If you (like me) avoid red-pill hassle, then just run (as root) an After you install that repo, of course...