UpAlert
cat@vv.carleton.ca
http://vv.carleton.ca/~cat/
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This program, actually developped out of necessity at the time, allows
you to monitor you connectivity to a certain service on a server. 
Basically, this determines when the server is "up". Best of all, it's
extremely small (a tiny 40K) and efficient. It simply adds an icon to the
system tray, has a thin yet usable configuration interface, and it doesn't
bog your system up with useless aesthetic add-ons.

It is very useful when you really need to do something on a server, 
but it's down due to maintenance. This program saves you the trouble of 
periodically checking the server. Simply enter the server host name or 
IP address, the port of the service and optionally customize the way it 
will notify you when the service is usable, and you can continue 
doing something else without worrying.

FAQ
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Q: How do I set the timing parameters?</td></tr>
A:

Poll interval: This parameter lets you choose how often UpAlert checks
the service to see if it's up. Some people might want to set this very low,
but please think your choice carefully.

On my system, it takes 64 bytes to
attempt a connection. The underlying TCP/IP stack usually also has a
retransmit timer of its own. From personal observation, it is approximately
3 seconds and it times out after 3 attempts. That means that, in 1 hour,
you'll send 3600 / 3 = 1200 packets. 1200 * 64 = 75 Kbytes of data.

Think what you could have done with those 75 Kbytes! Downloaded this program
almost twice, sent more than 10000 words in IM conversations, transferred more
than 20 e-mails from your e-mail server. Anyway, you get my point. Nobody needs
this value lower than 30 seconds, and 120 seconds (2 minutes) does its job
nicely enough for anybody.

Flash interval: Now, here, do whatever like. It no longer affects the
network, only your computer. (Muhahahahaha!)<br>
Okay, seriously, this sets how often the tray icon flashes when UpAlert
enters a state where it's supposed to flash. It is measured in milliseconds
(thousandths of a second) and if you divide 1000 by this number, you'll get
the number of times the icon flashes every second.
I have found that the value 300 is rather pleasing to the eye, and it is
the default. However, lower values make it flash faster and thus attract
more attention. You might want to experiment and see which value suits
you best. (This can be done by setting the "Trying to connect" state to
flashing and Apply'ing.)

Q: What's up with the "Status behaviors" section?
A:
It allows you to customize UpAlert's behavior when certain situations arise:

"Trying to connect" is the first state: before and while
UpAlert is attempting a connection to that service.

"Offline" means that the connection was either rejected (which could indicate
a misconfiguration on the part of the server) or timed out (the host is
unreachable, most likely down). In either case, the direct consequence is
that the service is unusable.

"Online" means that a connection was successfully established to the
specified port, therefore the service is most likely usable.

Finally, "Error" means that some unexpected error was encountered. In
most cases, this is due to a badly configured TCP/IP stack on the part
of the client, or lack of system resources (less common).

Q: What is the "Resolve host name on every check" option?
A:
This controls whether UpAlert tries to resolve the host name
you entered every time it checks for service availability. (This option
obviuosly has no effect on IP addresses, since in that case, there's nothing
to resolve.)

This is useful in some cases, for example if the host's DNS entry is expected
to change. Just set the host name that points to the old IP address and
UpAlert will keep re-checking the DNS records for the new IP address.

To resolve on every check is the default behavior, but in order to save
another few bytes for the DNS queries, you can disable this option safely
if you know the host's DNS records won't change while monitoring. In this
case, UpAlert resolves the host once you press OK, and re-uses that IP
address for monitoring.