I think the issue is the device I'm trying to connect to may have a modified ssh binary, it's a cyclades appliance (linux 2.2.14 variant). The script works on an actual linux server running SSH-2.0-OpenSSH_3.6.1p2, however the appliance is running SSH-1.99-OpenSSH_3.8.1p1. hostname: Doing challenge response authentication. Password: (This is where it hangs, if any input is passed it returns) input must be 8 bytes long at /usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi/Crypt/DES.pm line 57, [STDIN] line 1.