Linux




Convert mb4 to mp3 files in one run with ffmpeg

Folks at Defcon.org have been somewhat inconsistent in publishing their conference audio archives - once they do it in mb4 format, once in mp3 . As I listen to them on my mobile phone during my commuting to the work and it doesn't accept anything but mp3 I had to first …



You need no MX record to get mails

That one is funny. One client of ours that is actually themselves provide ISP services in a far-far-away land asked to add PTR record for their mail server . But that was dull, the interesting part was that their domain had absolutely NO MX record ! Only A record for the mail …



Skynet got blacklisted - Google mail servers entered RBL of Sorbs.net

When yesterday my client sent me the headers of blocked by eSafe (Aladdin) mails I was quite surprised - the message said " Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this …



List of valid domain names for load testing DNS

I am currently running a bunch of tests on DNS resolver software called Unbound to see what it is worth and for that needed a list of valid domain names in different but controllable TLDs. The only resource to download such list I could find was 3 million records file …



Query non-standard port of SNMP with snmpwalk

TLDR: Add colon to the IP address (no space), then the custom port. Sometimes the simple things are the ones to perplex us the most . Today I needed to add an SNMP monitoring of the Radware Linkproof load balancer listening on the port 7777 . Not a big deal, I thought …



MAC finder script

While I don't like going down to Layer 2 , recently I had to do it - I didn't know IP address of the Cisco router I wanted to connect to but I had access to the Cisco router sitting in the same network. That would be pretty easy to do #show …



Solaris interfaces – create assign delete

Working with interfaces in Solaris is pretty much the same as in Linux - you've got ifconfig, netstat,route. It looks in output a bit different but if you're used to the *BSD way of things you'll find yourself at home. So the most basic thing follows - bring interface up, assign …



How to choose the password that noone can guess and you cant remember

Of course you know what the good password should be - random letters including capitals, peppered with numbers and enhanced with printable control characters. The only problem with these recommendations is that there are very few people in the world that can memorize such incomprehensible sequence of chars. So if someone …



Top 10 usernames used in SSH brute force

As a follow up to yesterday's post I thought it would be interesting to know statistics of the usernames used in those brute force probes. Find below awk/sed script to get usernames for failed ssh login attempts from OpenSSH daemon and sort it for statistics. Also I attach the …



SSH brute force is on the rise, awk script to count failed SSH attempts

SSH brute forcing is still in high demand. I have , for my own testing and pleasure, virtual servers scattered around the world. All of them being of the Linux/BSD family I manage by SSH. Also I have on purpose no static IP at home for various reasons (saving me …