Daily Archives: 16/11/2006

Greylisting With Exim

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I recently trialled and then implemented greylisting on a few Exim mail servers, seems pretty straight forward when you know how to add it to the Exim config. I guess I ought to post that config snippet in case it is of use to anyone as it took me a few goes to get right. On Debian and derivatives you need exim4-daemon-heavy and greylistd. You will also need to add the Debian-exim user to the greylist group and ensure that /var/lib/greylistd/whitelist-hosts is group readable.

I use Vexim for added ease of use as most of the integration of Spamassassin and ClamAV is done for you and it provides a web interface to managing virtual domains and users. Therefore my config is different from the Debianised split config. I used dpkg-reconfigure exim4-config to tell exim to use a single config file.

Note the commented out line, this was necessary to make it work with my customised Vexim setup. Yours may well be able to use it so leave it in to start with. I put this in vexim-acl-check-rcpt.conf, which of course you won’t have unless you’re using Vexim, so you’ll have to work out where to put it. I guess I can make edits if people tell me the details.

Give /etc/greylistd/config the once over to make sure it’s set up how you want it, I set my retry period down to 10 minutes as I have users who have time sensitive emails. Also look at /var/lib/greylistd/whitelist-hosts to allow all of the machines you need to be allowed straight through.

With Vexim, you are also using SMTP authentication by default so it would be nice to allow your users through without having to find another means of not greylisting them. If you don’t use SMTP authentication you’ll have to find another way and take out the !authenticated = * line.

This is essentially taken from the greylistd /usr/share/doc/greylistd.

Due to problems with getting WordPress to format the code for me and not hide the backslashes, I have removed the actual config and instead point you to my wiki article on greylisting. Apologies for that.

There are extra bits of config that allow you to catch emails with no envelope sender address, but I’ve not set this up satisfactorily yet, so answers on a postcard.

Other links to Exim Greylisting are at the following:

http://www.debian-administration.org/articles/167

http://www.tldp.org/HOWTO/Spam-Filtering-for-MX/exim-greylisting.html (didn’t work for me)

http://spod.cx/blog/greylisting_with_exim_spamassassin.shtml

Do You Know Whats Wrong With My Guitar?

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Ok, I said had a few “Dear Lazyweb”s. This is the second in the series.

I put my home ‘studio’ back together to work on Jokosher as I had moved my PC, laptops, guitars and amp to my parents house before I went on holiday in case I was broken into while I was away. I have been twanging away quite a bit since I got back and now a problem with one of my guitars is really starting to bug me.

My Telecaster seems to have a tuning problem, it’s something that I noticed shortly after I bought it and at first I just thought I wasn’t tuning accurately enough, but it has become quite apparent the more I play it. It’s not that it won’t stay in tune which is a common problem with cheap guitars, more that it is out of tune after it has been tuned.

Basically, on a guitar, you have the body, which is the large part, the neck, which is the long thin bit with the wire strips across it and the head which is the bit on the end of the neck with with the tuning pegs on it. The strings are wound around the tuning pegs (aka machine heads) and then rest on a thing called the nut which sits on the join of the head and neck. At the other end, the strings rest on something called the bridge before going through the tail piece to keep them in place. When you pluck a string, it vibrates between the nut and the bridge and the vibration over the length of the string result in the pitch of the note that is heard. On the neck, those wire strips that go across the width are called frets and when you put your fingers between them, it causes the string to be shortened and hence create a higher note as the vibration is over a shorter distance.

Now, the problem I have is that when the the strings are in tune and played open, ie not using any frets, the note is in tune. When you play the note at the 12th fret, the string is in tune. If that isn’t the case it means the bridge or string saddles need to be adjusted. This wasn’t the case at first on my Tele and I had to adjust the saddles but it didn’t solve the main problem. The problem is that despite being in tune when open and when ‘fretted’ on the 12th fret, 2 strings particularly, B and G are out of tune on the second and surrounding frets, which makes playing chords or notes near that fret sound ugly as hell. Which means the guitar has a serious problem and can’t be played properly.

The problem gets better nearer the 12th fret, but that isn’t the point. The only other thing I can think of is either a) the guitar is fucked and needs to go back, which is a hell of a shame, or b) the truss rod needs adjusting, which is the limit of my knowledge about being a guitar technician and also, is beyond my experience which means it needs to go back to the shop. The truss rod is a metal rod in the neck of the guitar to keep the neck from bending or folding altogether under the tension of the strings. Anyone who knows better than me is welcome to make suggestions.

Problems with Jokosher/Gnome Audio/ALSA/DBUS/Ubuntu Edgy

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I’ve been helping test Jokosher again, just as we come up to the second development release, but sadly I seem to have a problem with Jokosher recognising my Creative Labs Sound Blaster Live 5.1 since upgrading to Edgy. It all worked fine in Dapper. Please help if you have any understanding of DBUS, Gnome audio and ALSA. I don’t know where to go from here. So for now I’ll have to use my limited spare time on trying to help the docs team.

On a side note, check Jokosher out if you are interested in Linux audio production, we’re always looking for developers.

Been Around the World

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Well actually haven’t but it feels like I have. I only went to Cyprus but it’s been chaos since I got back. It’s been a while so here’s a rundown.

Went to Cyprus, the Turkish part. It’s really nice, very peaceful where I went but you can see the place is in the middle of (re)development. It has suffered from under investment since the split with the Greek side but you get a sense that they are suddenly becoming aware of the income from tourism. Most of the place seems to be either run-down and covered in patches of debris or is being developed as fast as you can see, there are homes and apartments being built everywhere. Still, worse than British workers, there seem to be 7 or 8 people doing construction job and all but one of them are watching the other one do something small and fiddly.

I turned 30. I didn’t celebrate other than go for a meal with my family. Not that I was pissed off or depressed at my passing youth, merely that I just couldn’t be arsed. I really don’t feel like going out and getting wrecked these days, which was pretty much par for course during my late teens and 20s. Guess I’m getting old, but I can neither afford to waste money in such a way, nor waste the day afterwards recovering and more often than not, the day after that too. Some of my best friends also turned 30. Happy birthday to Rich, Adele, Anna, Joan, my nemesis Felim Whiteley who all share the same birthday as me and are also not listening apart from Felim probably. Hope you’re well my man, oh and by the way, someone left you a message in my comments. I can mail you his address if you don’t already have it.

I started doing a CCNA, funded by work, this is kinda cool but it’s all theory at the moment. I’m looking forward to playing with routers and stuff. It’s a real struggle to find the time to get my work done, especially with 2 or 3 weeks to catch up on after my holiday but I’m almost back up to date.

My mobile phone seems to be a bit fucked. The signal has always been a bit weak at home, but I’ve had calls drop out without signal problems and SMS messages that didn’t turn up. If you sent me a message and I didn’t reply then I can only apologise. Worse than this is the fact that the screen is now fuzzy in the top half and it’s a struggle to read messages some times. Ahh well, I’m not going to waste money I don’t have buying a new one when I’ll get a new one in March. Still I gotta wait for about 4 months with a dodgy phone.

I reinstalled my Ubuntu desktop with Edgy, which was kindly released on my birthday. The main reason was to make a clean sweep as both me and Aq wondered in the when we upgraded to Dapper whether we had missed out on some of the wizzy bits and pieces by doing so; and also to put my /home partition on Linux software RAID so I could play with it.

At work I’m busy as always. Top projects are still Asterisk, which I’ve been away from for quite a while, but which may well become quite important and a few other things. I have a number of “Dear Lazyweb” requests coming up so may well be asking for your advice.

I also have to learn PHP which is going to be a challenge given that I’m already short on time and doing a CCNA. Anyone got recommendations for PHP5 books or courses? My employer would like a number of us to learn at the same time, in a semi-organised way.

Oh yes and I’ve been ill for the last week. I was in a bad way Sunday and Monday, went in to work for a meeting feeling lousy on Tuesday but have been getting better since. My throat is still really sore and my chest is heavy, I haven’t smoked since I’ve been ill and I’m having sleepless nights. Hopefully I’ll be properly recovered soon.

That’s all for now, no doubt I will think of more stuff to write after hitting submit and will then take another 6 weeks to write them out. Hope you’re all well you kerrazy kidz.