The Term Protocol
Term is very flexible with many configuration options on the command line as well as in the .termrc file. Running term is much like running linecheck:
Using a communications program, dial up your remote account and log in
Start term from that account. A sample command line might be:
term -l $HOME/tlog -s 38400 -c off -w 10 -t 150 -r
This command line indicates:
Set the log file to tlog in your home directory
Set the line speed to 38400 bps
Turn off term's compression (presumably because your modem does better compression)
Use a window setting of 10 (explained in the term documentation)
Use a timeout of 150 (explained in the term documentation)
Set this as the ”remote“ side
Shell back to your local computer, either by suspending your terminal program, or using its built-in shell features. For Kermit, use ctrl-Z, for xcomm use ctrl-a-x. (Check your specific terminal program's own documentation.)
Initiate term on your local computer:
term -c off -l $HOME/tlog -s 38400 -w 10 -t 150 < /dev/modem > /dev/modem &
The only difference in this case is the redirection to the modem device and lack of the -r option.
It should be noted that all of the command-line arguments can be placed in the . termrc file so you need only type term by itself to initiate it:
.termrc: compress off speed 38400 window 10 timeout 150
Note that you will still need to put the redirection on the command line.
The standard term clients trsh, tredir, tmon, ”upload, and txconn are relatively easy to use. The most commonly used utility is trsh.
trsh is used to access your remote account as if you were using rlogin to access it. trsh can also act like rsh and execute commands on your remote host:
% trsh Remote: term 2.0.4 tty /dev/ttyp4. exec /usr/local/bin/tcsh foober : /home/ j oeuser% % trsh -s uptime 1:15am up 20 days, 17:30, 3 users, load average: 1.00, 1.00, 1.00
The most utilitarian of the term clients, this command allows you to manually redirect TCP/IP ports for use with term. For example, to allow incoming telnet sessions to your home computer, you need to redirect a port on the remote host to your own telnet port, which is port 23. The common command format of tredir is:
tredir [thiscomputer: ]port [thatcomputer: ]port
By default, the first port is the port on the machine you are running the command on, the second port is the port value on the other computer you are redirecting to.
In this example, I want to redirect port 4000 to my own port 23:
remotehost% tredir 4000 23 Redirecting 4000 to 23 remotehost% telnet localhost 4000 Trying . . . Connected to localhost. Escape character is '^] ' Linux 1.1.35 (linuxbox) (ttyp3) linuxbox login:
Another example of use of tredir is to configure your system to allow reading news via your network's NNTP news server. This requires a tredir on the local side of term, instead of the remote:
linuxbox% tredir 119 news. server.com: 119 Redirecting 119 to news.server.com:ll9 linuxhox% export NNTPSERVER=localhost linuxbox96 trn
[normal trn session follows]
Notice that in this example the NNTPSERVER variable is set to localhost. This is because the local 119 port has been redirected to the real network NNTP server. So any connections to the localhost NNTP port is redirected to the real one on the remote computer. A direct connection to the actual NNTP server (setting NNTPSERVER to news.server. com) would not be possible on a term link, unlike SLIP/PPP which would allow this. tredir makes possible the use of many applications that use standard TCP sockets, such as sendmail, IRC, MUD's, MUCK's, and many other similar multi-user games.
This is the term equivalent of sz or other file upload/download protocols. It allows the transfer of files from the local machine to the remote, or vice-versa, depending on which end the command is initiated. Commonly, the command line would look like:
linuxtox% tupload foot tar. gz
Which would send a copy of the file foo.tar.gz to the remote host. Some useful flags are illustrated below:
linuxbox% tupload -vv -p -16 foo.tar.gz Changing priority to -16 sending foo.tar.gz 30651 of 259727 (11%), current CPS 3083. ETA: 76.8 TT: 84.2
The -vv flag means give verbose messages on the status of the upload, while -p means change the term priority of the upload. This prioritizing allows you to nice a term process so it doesn't hog bandwidth from the other term applications you may be running. This is useful for large background transfers.
One Click, Universal Protection: Implementing Centralized Security Policies on Linux Systems
Join editor Bill Childers and Bit9's Paul Riegle on April 27 at 12pm Central to learn how to keep your Linux systems secure.
Free to Linux Journal readers.Register Now!
|diff -u: What's New in Kernel Development||Aug 20, 2014|
|Security Hardening with Ansible||Aug 18, 2014|
|Monitoring Android Traffic with Wireshark||Aug 14, 2014|
|IndieBox: for Gamers Who Miss Boxes!||Aug 13, 2014|
|Non-Linux FOSS: a Virtualized Cisco Infrastructure?||Aug 11, 2014|
|Linux Security Threats on the Rise||Aug 08, 2014|
- diff -u: What's New in Kernel Development
- Security Hardening with Ansible
- NSA: Linux Journal is an "extremist forum" and its readers get flagged for extra surveillance
- Monitoring Android Traffic with Wireshark
- Tech Tip: Really Simple HTTP Server with Python
- [<Megashare>] Watch Mrs Brown's Boys Movie Online Full Movie HD 2014
- RSS Feeds
- Readers' Choice Awards 2013
- Linux Security Threats on the Rise
- Cooking with Linux - Serious Cool, Sysadmin Style!