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My Scriptorium on GitHub

I consider myself something of a toolsmith... when solving problems I often end up writing a script (or lengthy 'one-liner' more likely). Sometimes that script ends up being rather useful and I find myself using it frequently. Now you can perhaps benefit from this too (and perhaps improve on it).

You can find a hand-picked assortment of widely applicable such scripts and tools in my scriptorium on GitHub. If you're an admin of Linux systems (or Unix systems), then there may be something of use for you there.


Popular posts from this blog

ORA-12170: TNS:Connect timeout — resolved

If you're dealing with Oracle clients, you may be familiar with the error message
ERROR ORA-12170: TNS:Connect timed out occurred I was recently asked to investigate such a problem where an application server was having trouble talking to a database server. This issue was blocking progress on a number of projects in our development environment, and our developers' agile post-it note progress note board had a red post-it saying 'Waiting for Cameron', so I thought I should promote it to the front of my rather long list of things I needed to do... it probably also helped that the problem domain was rather interesting to me, and so it ended being a late-night productivity session where I wasn't interrupted and my experimentation wouldn't disrupt others. I think my colleagues are still getting used to seeing email from me at the wee hours of the morning.

This can masquerade as a number of other error strings as well. Here's what you might see in the sqlnet.log f…

Getting MySQL server to run with SSL

I needed to get an old version of MySQL server running with SSL. Thankfully, that support has been there for a long time, although on my previous try I found it rather frustrating and gave it over for some other job that needed doing.

If securing client connections to a database server is a non-negotiable requirement, I would suggest that MySQL is perhaps a poor-fit and other options, such as PostgreSQL -- according to common web-consensus and my interactions with developers would suggest -- should be first considered. While MySQL can do SSL connections, it does so in a rather poor way that leaves much to be desired.

UPDATED 2014-04-28 for MySQL 5.0 (on ancient Debian Etch).

Here is the fast guide to getting SSL on MySQL server. I'm doing this on a Debian 7 ("Wheezy") server. To complete things, I'll test connectivity from a 5.1 client as well as a reasonably up-to-date MySQL Workbench 5.2 CE, plus a Python 2.6 client; just to see what sort of pain awaits.

UPDATE: 2014-0…

From DNS Packet Capture to analysis in Kibana

UPDATE June 2015: Forget this post, just head for the Beats component for ElasticSearch. Beats is based on PacketBeat (the same people). That said, I haven't used it yet.

If you're trying to get analytics on DNS traffic on a busy or potentially overloaded DNS server, then you really don't want to enable query logging. You'd be better off getting data from a traffic capture. If you're capturing this on the DNS server, ensure the capture file doesn't flood the disk or degrade performance overmuch (here I'm capturing it on a separate partition, and running it at a reduced priority).

# nice tcpdump -p -nn -i eth0 -s0 -w /spare/dns.pcap port domain

Great, so now you've got a lot of packets (set's say at least a million, which is a reasonably short capture). Despite being short, that is still a massive pain to work with in Wireshark, and Wireshark is not the best tool for faceting the message stream so you can can look for patterns (eg. to find relationshi…