Linux

Notes on Encrypted /home directory, post install.

by

I decided to encrypt the /home directory on a notebook, post install, as I was going to take it out of the house. There's nothing too important on it, but I probably should look after my ssh keys at least! The laptop is a low end Dell, running Mint (based on Ubuntu). It has a slightly odd configuration in that I have the /home partition mounted separately.

OK, so the first thing I did was to copy the big files onto a separate, non-encrypted partition. I did this for two reasons. Firstly the encryption process creates a copy of your home directory which you can roll back to. This means in your /home partition you need enough room for two copies of your home dir. I didn't. Secondly, the encryption process obviously encrypts each file as it goes. I thought by moving out the large files (Music and Videos directories basically), that this would speed up the encryption process.

Read more

mysql not starting – errno: 24 – Too many open files

by

This was a really strange one and might be peculiar to debian servers. I was trying to change a couple of mysql default settings, so after editing the config file, I restarted mysql on a webserver and it didn't come back up again. There were a bunch of errors in the /var/log/mysql.log saying "errno: 24 – Too many open files". And in fact mysql was so busy pumping these errors out, that it didn't have time to do any databasing on the files it was able to open.

After a bit of experimentation (read 'panic'), I discovered that rebooting the server started mysql up fine, but doing a 'service mysql restart' produced the file errors, so I rebooted and left it running while I investigated.

Read more

WordPress Multisite Blog Mass Removal Script

by

I was moving a WPMU site to a new server and saw that the database had grown to about 250Mb, and there were about 700 blogs running on the server. I used a few database queries to pull out a list of which blogs I wanted to delete — basically any which had a creation date and last update date the same, and any with only one post etc — at which point I had a list of 300 blog IDs. So was I going to manually delete them all? Nope, I did what any sensible person did, and wrote a script to do it.

Read more

vnstat for webservers

by

This is quickly becoming one of my favourite tools when setting up webservers, after discovering it recently. I have all sorts of monitoring set up and use munin a lot, but vnstat seems to be a very lightweight daemon which gives you insight into the traffic to and from your box. Best of all it integrates well with logwatch, so it will send you a quick report every day so you can see immediately if something is going wrong.

Read more

UFW script for Logwatch

by

I enabled UFW on an Ubuntu server recently and started getting all manner of stuff in my logwatch reports. It activated a section called 'iptables' and started logging every line in syslog with [UFW BLOCK] in it. It was marginally interesting, but not really worth the space devoted to it, so I decided to write a little script to parse the UFW log and summarise the top Blocked Hosts and top Blocked Ports. Therefore I could easily see if there was a change in pattern.

Read more