Luke Sheldrick’s Blog

Well what a week, glad it’s over

Has been quite eventful, but over all quite boring.

I broke my Dell Laptop screen a couple of weeks ago, and hadn’t got around to fixing it as yet. In a meeting earlier in the week, a project that had been put on hold came up, which i had been working on, but had been put on hold. As I am leacing the company pretty soonish, they wanted it completed. Hmm. The source code is on the laptop, the laptop screen is broken. Tried plugging in a VGA monitor, but seems as default is not enabled in the BIOS. No amount of screen pressing got it to work either. The HD is encrypted, using details from the mobo, so wont boot in another machine. Excellent the only thing really is to either pull two laptops apart and bodge it (which none of us wanted to do) or get it fixed.

As its my own kit (used as I have licensed versions of the dev tools) they wont repair it… great. Anyways come to some compromise, and they said I could go and get it fixed Thursday. The place is near Heathrow, and for times sake, I drove it there.

Thats where the fun starts, Thursday is really pants weather, so much so that visibility is really crap on the M25. Anyways doing about 50ish in the outside lane, then without knowing about it, I am spinning over ever carriage. I had hit the brakes, as there were three cars pilled up in the outside lane, but as its so wet, my car span. I ended up stopping a cm away from the crash and the central reservation. Then I see a TT doing the same, stopping a CM from me.

I looked at the chap, and laughed. Then thought shit better get out of here before someone crashes into me. with that went to Heathrow, got my lappy repaired, and back home (well the office anyways). Thought as it was mid-day I’d pay the CC charge and go through central London. Seems the CC change hasn’t actually cut traffic, but you just have to pay for the privilage.

Later on in the week, I was getting a server ready for sticking in a colo, as when I leave my current job, I loose the nice perk of having a server in the DC. I had some LP2000r’s lying around that I use for testing and running a couple of VM’s. One had a few warnings, i.e. the fan had died…etc, so thought I would strip that one down, and make 2 more powerful beasts, with some spares for the future.

In doing so managed to reset the raid on one of them. Needed to rebuild the OS anyways. My primary exim box, which is a virtual died a couple of weeks, ago, so was running off a backed up version, which also has now died. So had to rebuild that, and made a couple of spares too.

Friday saw KCOM being particularly up to spec (that’s sarcasm there, if you didn’t guess), so this is definitely coming up to my last week.

I often wanted to have the ability to have email addresses such as myname+somethingrandom@mydomain and it go to myname@mydomain however as far as I know, exchange is unable to support such a nice feature.

However as I earlier blogged, I now have 2 exim front ends, so I asked a quick question on a mailing list, and they gave me a few links. Seems with just two lines of code, I can get this all to work. Just by adding

local_part_suffix = +* : -*
local_part_suffix_optional

To my routers config, it does what exactly what I wanted.

If you was wondering why I wanted this, whenever I now give my email address out, I can give it out in the style of myname+sideaddress@domain and it will always come to my mailbox. However if I then start to see lots of spam to any paticular +variable, I can tell what nasty site sold my email addy.

Last week, I started working on a new mail platform. I had in place, an Exchange 2003 box at home, and a backup mail server running Exim, based in Global Switch London.

I utilised Greylisting on both, however found the linux version ten times better. So set myself a task to setup a new front end, in front of my main Exchange box. Ruled out getting rid of it totally, as I personally prefer the features of Exchange (Push mail, calanders…etc).

So I setup a virtual machine (CentOS 4.4) on one of my virtual hosts, configured exim, with greylisting, and to relay all mail to my domains, to the internal IP of my Exchange box. I also wanted to setup a test Exchange 2008 box at the same time, so anything to my development domain, would go to a different internal IP.

After a few tweaks, magically it all worked… until I started to get NDR’s  stating that mail was being delayed to my domain. A few telnet tests later, discovered that if you connected from a host with no rDNS, my mail server took 30 seconds to time out doing a reverse DNS check. Many mail servers would have timed out by this time. A quick tweak of my exim config to lower the DNS time out, from 30 seconds to 5, cured the problem.

For anyone wanting to do this, edit the exim.conf lines

rfc1413_hosts = *
rfc1413_query_timeout = 30s

to

rfc1413_hosts = *
rfc1413_query_timeout = 5s