Here are a couple of packet radio software options depending on your
computer and operating system.  We recommend/prefer "OutPost" because
of its ability to automatically navigate a multi-node path to reach
a BBS, or Winlink server.  But it also has a regular 'standalone' 
terminal program for TNC commands, etc.

• Outpost Packet Message Manager
  (Windows 98 thru 11; Linux; Raspberry Pi)
• PuTTY: free SSH and Telnet client (xterm emulator Windows & Linux)
• EZterm: for Windows XP, Vista, 7, 8, 10
• Additional software options