telnet is fine, but ssh is better

on your hp procurve switch cli:

# configure terminal

(config)# crypto key generate ssh
          will generate host key (rsa)

(config)# ip ssh
          will enable ssh server daemon
          * nb: by default, if a password is not set, then ssh root@switch will
          function... sans password 

(config)# no telnet-server
          adeus telnet...

(config)# write memory

once done, this also means that one may no longer use free HP OpenManage switch tools to configure the switches.