Apples "telnet" is broken

“telnet” is a program that lets you make an unencrypted login to another host on an arbitrary port. It is a useful testing tool, for making sure that the firewall you’re working on is working; or for making sure the service you are working on is answering. Normally you give it a hostname and a port number. Simple. Only, with apple, if you give it port 25 (“SMTP”), it decides not to do a regular host to IP lookup, but instead… does a MX record lookup. As in, it goes somewhere other than where you told it to go.

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Jason-Feslers-computer:~ jfesler$ telnet gigo.com 22 Trying '‘‘216.218.228.114'‘‘… Connected to gigo.com. Escape character is ‘^]'. SSH-2.0-OpenSSH_4.5p1 FreeBSD-20061110 ^] telnet> close Connection closed. Jason-Feslers-computer:~ jfesler$ telnet gigo.com 25 Trying’’’ 216.218.228.118'‘‘… Connected to mx2.gigo.com. Escape character is ‘^]'. 220 goat.gigo.com ESMTP secondary mx only defers/rejects. postmaster@gigo.com ^] telnet> close Connection closed. Jason-Feslers-computer:~ jfesler$ `

Update:  This happens for ssh, nc as well.  As it turns out, Apple’s doing this on quite a bit.. http://blog.jungledisk.com/2007/10/31/leopard-dns-issues-and-work-around/