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Old 23rd July 2008
BSDfan666 BSDfan666 is offline
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OpenBSD's FAQ answers your question:
http://www.openbsd.org/faq/faq7.html#SerCon
  • Recording console output (for documentation).
  • Remote management.
  • Easier maintenance of a large quantity of machines
  • Providing a useful dmesg from machines which might otherwise be difficult to get one from.
  • Providing an accurate "trace" and "ps" output if your system crashes so developers can have a chance to fix the problem.

I use them for maintenance, but historically it was the only way to interface with Unix systems.

All terminals have a tty device associated with them.. on OpenBSD, the keyboard/mouse and monitor are presented to the system as several "vt100-compatible" terminal devices.

Example:
wsdisplay0 at vga1 mux 1: console (80x25, vt100 emulation)
wsdisplay0: screen 1-5 added (80x25, vt100 emulation)
wskbd0 at pckbd0: console keyboard, using wsdisplay0
wsmouse0 at pmsi0 mux 0

/dev/ttyC0 being first console, /dev/ttyC5 the last, switching between virtual consoles is done via CTRL+ALT+Fn keys.

SSH/RSH/Telnet connections use use pseudo-terminals, aka "pty" devices..

Now, "getty" plays an important role on Unix systems, it manages the initialization of terminals and invokes the login(1) program when appropriate, by default, getty isn't usually listening on your serial ports...

The first serial port is typically "ttyp0", so to use that..

In /etc/ttys, I would change:
tty00 "/usr/libexec/getty std.9600" unknown off
to:
tty00 "/usr/libexec/getty std.9600" vt220 on secure

And that's about it... to use this port, you'll need a "null-modem" cable and terminal software on the remote system.. "secure" in the above line permits root login.

Last edited by BSDfan666; 23rd July 2008 at 09:56 PM.
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