Ok folks, for any of you out there that manage Solaris machines (or want to), I have written up an article detailing one of the fundamental and basic things you do a lot of. Creating disk mirrors with SVM or Solaris Volume Manager. Now, this article does more than just tell you how to create the mirror, although it does do that. In addition, I tried to explain what was going on so that you could get an understanding of what was happening when you were running the commands. In the near future, we’ll have more articles dealing with SVM on such topics as how to replace a failed drive, and even other RAID options. For now though, we dig in to the area of mirrors. Check it out, I hope you find it useful!
Finding the right RDNS blacklist from SANS
Anyone reading this post, that also runs a mail server should immediately know what I am talking about. Reverse DNS blacklists for mail servers to stop spam. What are these lists? Well, these are lists of known bad senders (open relays, spambots, spamfriendlies, whatever) that are maintained and setup to act like a DNS server. When you configure your mail server (and some clients too! Mailwasher anyone?), you can tell it to check all incoming mail senders against the blacklist, and then what to do if they are on it, like bouncing, deleting, tagging, etc. Basically, it works by doing a reverse DNS lookup agains’t the blacklist server, if the address in question is found (i.e. it resolves), then it’s a match and the mail is dealt with. These are very handy for helping slow the flow of spam. Here is an article from SANS about how to pick a good one, and some things to look out for. This is a good read from a good place, check it out.
Google using too much energy?
This is actually kind of funny, at least I got a chuckle out of it. There is an article on Slashdot that talks about Google and how the folk at Nature Climate Change is arguing that Google’s white background is using too much electricity to display on all of our monitors, and that if they would just change to a black background it would save the world, end global warming, feed your dog, and make your girlfriend come back. Sounds kind of silly to me, but then again, look at how many tons of weight they shaved off of the space shuttle by not painting that big fuel tank!
Super Network Tool Bundle
Need a bundle of network tools? I mean one application that can ping, traceroute, nslookup, whois, and more? With advanced features like SMTP open relay checking and DNS zone transfers? A tool that doesn’t cost hundreds of dollars? The list goes on, have I enticed you enough? Good!
I found this app a long time ago, and it is steadfastly entrenched in my kit to this day. It’s called Sam Spade, and it’s named after the famed detective to be sure. The folk that wrote it offer it up for free, and it’s a very handy tool for anyone that ever needs to do network type work. Spend a few minutes reading up on it, and going through setting the settings, it’s worth it although it’ll work out of the box. I think you’ll find it a valuable tool too.
Simple PERL file backup script
I am one of those type of people that like to make backup copies of files before I tinker with them, especially when I am modifying important files like system stuff. It’s always a good idea to make a backup copy before you edit something so you can put it back if you break it. For that reason, I wrote this simple little PERL script that I then put somewhere in my path so I can run it from anywhere. I call it simply “bu” so that it’s easy to type and use. What it does is copy the target file you specify, to a file of the same name only with a date stamp appended to it. I have found this to be a really handy tool, so I thought I would share.
Take a look at the script here.
Check it out, I hope you find it as useful as I have.
Make your crontab more user friendly!
All you *nix users out there are probably just like me. You use cron a lot, and for some mighty important things. However, you just don’t quite use it enough to keep the exact order of the values for when to kick off a job in your head. Well, for me, an easy way to help that is to put what I call headers into your crontab. These are in fact comments, but they spell out what to put where and act as a reference so you can get back to getting work done, instead of googling for the information! Check it out:
# minute (0-59),
# | hour (0-23),
# | | day of the month (1-31),
# | | | month of the year (1-12),
# | | | | day of the week (0-6 with 0=Sunday).
# / | | | | commands
3 2 * * 0,6 /some/command/to/run
3 2 * * 1-5 /another/command/to/run
How’s that? Pretty nifty, huh? Be sure to take out the last two lines that I stuck there for examples.
Enjoy!