zeroxcool.net – Harm van Tilborg

Not quite an active log, huh. Time to change, I’m not going to tell you what I’ve done and what I didn’t, just anything I _would_ like to talk about. It was just annoying to tell everything I’ve done this week, so there wasn’t a motivation to log. Well, now there is.

This week I’m having a week of vacation. Well, vacation, let’s say, not going to school. Because I had to do lots of things for school this week. We’re working on a GPS program (on PDA and desktop) to make it possible to set out walkings with a GPS device. Quite interesting project, but it takes lots of time. We’re still running on schedule, I hope in a few weeks I can show the final results.

At work everything is also fine. We’ve introduced – after months of testing – finally our virus- and spamscanning – mail exchangers. Our mail system is now much more reliable to outages of one particulair server. I’ve ASCII-arted an impression of the current situation:

	MX1	= mx1.mail.tiscomhosting.nl
	MX2	= mx2.mail.tiscomhosting.nl
	POP01	= pop01.mail.tiscomhosting.nl

	 /----------------\				/----------------\
========\|      MX1       |				|     POP01      |/==========
inet in	||   virus and    |========\		/=======|  POP archiver  || inet out
========/|  spam scanner  |        |            |	|		 |\==========
	 `----------------'        |            |	`----------------'
				   \[ internal ]/
				   /[ network  ]\
	 /----------------\	   |		|	/----------------\
========\|      MX2       |	   |		|	|     POPxx      |/==========
inet in	||   virus and    |========/		\=======|  POP archiver  || inet out
========/|  spam scanner  |				|		 |\==========
	 `----------------'				`----------------'

As you can see, mail only comes in via the two MX servers. They scan all e-mail on SPAM and virusses. Virus e-mail is immediately deleted, SPAM e-mail otherwise is being tagged with an striking subject name. After that it is forwarded through the internal network to the POP-servers, they store all e-mail for clients and give them out on request. The internal forwarding is done by SMTP and the POP-servers only allow SMTP-traffic from the internal network.

Well, if one of the MX servers is down, there’s no problem, the other one will still receive incoming e-mail. If one of the POP-servers fails, the mail is still being queued at the MX’s. They will deliver everything when the POP-server is comming back up. The only remaining problem, when a POP-server is down, clients are unable to download their e-mail, that shouldn’t be a big problem because the POP-server didn’t have a higher downtime than a half an hour last year. Nice solution we still think.

Tomorrow again a football match.