The Serial Console: A Front Door Worth Leaving Open - page 4
Foregoing Direct Neural Implants
Permissions inconsistencies are going to bite you a lot. By default on most Linuxes, root cannot login over a tty. So you'll have to edit or create /etc/securetty on your server, and add this line:
Non-root users can't use tty ports. The quick n dirty fix is this:
# chmod o+rw /dev/ttyS0
The long-term fix is set up sudo users for /dev/ttyS0.
A third show stopper nuisance is having mingetty. mingetty is strictly for logging into to local virtual terminals. It does not support serial lines. You want agetty, getty, or mgetty, which can be obtained from the usual Linux sources. If your system is using mingetty, don't remove it. Just be sure to edit /etc/inittab to point to agetty, getty, or mingetty.
- The definitive guide to the Linux Serial Console is the Remote Serial Console HOWTO
[Editor's Note: This article originally appeared in the JupiterWeb site CrossNodes.]