Tera Term is a free, open-source terminal emulator for Windows, released under the BSD license. It opens text sessions to remote hosts over Telnet and SSH, to devices on serial ports, to named pipes and to a local Cygwin shell. These connections make it a common tool for server administration as well as for configuring routers, embedded boards and other hardware with a console port.
Connecting to hosts and devices
A new connection in Tera Term is either a TCP/IP session or a serial session. For TCP/IP, the user enters a host name or address and picks Telnet or SSH. Tera Term supports IPv6 alongside IPv4. One command can duplicate Telnet, SSH and Cygwin sessions into a new window.
Users configure serial connections from a dedicated settings tab:
- port number and any numeric baud rate
- 7 or 8 data bits, parity (none, odd, even, mark, space) and 1 or 2 stop bits
- Xon/Xoff, RTS/CTS or DSR/DTR flow control, with manual control of the RTS and DTR lines
- live indicators for the CTS, DSR, RING and RLSD signals
- a transmit delay between characters or lines for devices that drop data
A break signal and a serial port reset are available from the Control menu. A Cygwin connection opens the local Cygwin shell in a Tera Term window.
SSH sessions through TTSSH
SSH support comes from the bundled TTSSH module, which handles both SSH1 and SSH2. Authentication can use a plain password, a private key (RSA, DSA, ECDSA or ED25519, in OpenSSH, PuTTY or ssh.com format), keyboard-interactive login, or keys held by the Pageant agent. A built-in key generator creates key pairs; the public key goes into the server’s authorized_keys file. When connecting, Tera Term checks the server’s host key against its known hosts file and warns if the key is missing or has changed.
Users set up port forwarding as a list of rules. Local forwarding opens a port on the PC and carries its traffic to a destination reached through the server. Remote forwarding does the reverse. Dynamic forwarding turns a local port into a SOCKS proxy. X11 forwarding lets graphical programs on the remote host appear on a local X server. Users can copy files in either direction over SCP from the File menu.
Terminal emulation and text encodings
Tera Term emulates the DEC VT100 with selected VT200 to VT500 features, plus ANSI color sequences and xterm extensions such as mouse reporting and 256-color mode. A separate TEK window handles Tektronix TEK4010 graphics. VT52 mode and double-width or double-height characters are not supported.
Users choose receive and transmit encodings separately. Options include UTF-8, the ISO 8859 family, Windows and DOS code pages, KOI8-R, Shift_JIS, EUC-JP and JIS for Japanese, CP949 for Korean, and GB2312 and Big5 for Chinese.
Session logging and file transfer
Tera Term can log received output to a file as cleaned-up text or as raw binary data. Users can write text logs in UTF-8 or UTF-16 and strip non-printable characters. They can also add a timestamp to each line. Timestamps can use local time, UTC or time elapsed since logging or the connection started. Users can later replay binary logs in the terminal window.
Besides SCP, Tera Term transfers files with the Kermit, XMODEM, YMODEM, ZMODEM, B-Plus and Quick-VAN protocols, which suit serial links and older hosts.
Macros and multi-window commands
Tera Term Language (TTL) is the program’s scripting language. A separate macro interpreter runs it. Scripts can connect and disconnect, wait for specific output from the host and send lines in response. Users typically build automatic logins and repetitive configuration jobs with these operations. TTL also has loops, conditions, string and file functions, and stored passwords. Macros start from the Control menu or from a shortcut that passes the script file to the interpreter.
The Broadcast command sends the same text to several open Tera Term windows at once. In normal mode, submitting a typed command sends it to the windows selected in a list. In realtime mode, Tera Term passes on each keystroke immediately.
Settings files and plug-ins
Users manually save settings to a configuration file, so they can keep and restore different setups. Plug-ins add extras such as TTY session recording, recurring commands and font size controls, and language files translate the interface.
