Quoting Jun G ([EMAIL PROTECTED]):
> Hello. Just a few 'wonder questions' which I hope would be answered here.
> How are serial cards different from terminal servers? What is Radius? Is it
> possible to configure your ordinary serial cards as terminal servers (or
> vise-versa)? If I want to have remote users dialing into my server, should
> I get a serial card or a terminal server? What's the maximum speed for
> these devices?
Terminal servers are dedicated machines for handling dial-up access (among
other things). Typically, a terminal server will be more reliable than a
computer with a multi-port serial card, although this depends on the quality
of the operating system on the terminal server. I have experience with
Livingston products and can recommend them without hesitation. The down-side
of terminal servers is their cost. The per-port cost of a Linux box with a
good multi-port serial card (and modems) will generally be signifigantly
cheaper for the hardware, however the setup time for such a configuration will
be greater so the end-result will not necessarily be cheaper. Additionally,
if you will be getting into a large number of ports, terminal servers become
much more manageable.
If you end up running a Linux box, there are a number of different ways to set
up the dial-in configuration. When I do this sort of thing, I like to run
pppd out of init so there is no way for a dial-in user to get a getty and
hence a shell. An inittab entry might look like this:
s0:4:respawn:/usr/sbin/pppd /dev/ttyS1 57600 -detach
Repeat as necessary for other ports. The /etc/ppp/options.ttyS1 for this
setup would contain entries for a chat script to initialize the modem, the IP
addressess -- you assign an IP address to each serial port, etc. The last
component for this setup would be a script to (for instance) munge the
password file (assign dial-up users to a single group) into either/or/and the
pap-secrets and chap-secrets file for authentication.
Logging connect times is slightly problematic, since wtmp entries have a one
minute resolution. Because of this, I wrote a couple of programs to do
logging when the connection comes up and down, and hacked pppd to run them in
the same manner that the ip-up and ip-down scripts are done. With this
arrangement, I achieve a one-second resolution for accounting purposes. I
ended up doing this because there wasn't enough information supplied to the
ip-up and ip-down scripts to satisfy my requirements.
If anyone wants the code, it is available as is a sinple patch to pppd-2.3.3
(2.3.1 contains a bug in the signal handling code and I have not yet been able
to compile 2.3.5). The code contains four programs: log-up, log-down which
are run by pppd, and pppwho and ppplast which are analagous to the who and
last commands. The ppplast command has the ability to select particular users
(or all of them) in particular date ranges in detailed or summary formats.
It's been in operation for almost a year and is stable, if not really
feature-rich.
I do not have the time or inclination to run a web-site, but if there is
interest, I will make the code available via FTP at an ISP I run. Initially,
though, I'll mail copies of the source to anyone who asks.
Regards,
Steve Thompson
[EMAIL PROTECTED]
--
"Bite the wax tadpole."
