This article details how to easily create a bootable Ubuntu USB drive that be completed in less than 20 mins (May be 10 if you’ve a fast usb drive). Having a faster USB drive would help in the long run too!
Note: this procedure requires that you create an .img file from the .iso file you download. It will also change the filesystem that is on the USB stick to make it bootable, so backup all data before continuing.
Tip: Drag and drop a file from Finder to Terminal to ‘paste’ the full path without risking typing errors.
I have been using Mac terminal to get a MAMP setup done lately and I kept running back in to and error I spent a lot of time trying to fix a while ago…sigh. This comes up when you try to install or update with brew.
Irshads-MBP:~ Ishy$ brew upgrade
Error: Cannot write to /usr/local/Cellar
Fix it this way:
sudo chown -R $USER /usr/local
Note: You can replace $USER to root as homebrew is better set with root.
I have been fascinated about IT security and firewalls. I was able to get some hands on exposure to firewall scripting if you like, during my Masters that I just completed. To rekindle my love towards this, I went back on my Ubuntu virtual machine and thought lets ‘try two simple tasks to do with iptables; adding and removing a basic rule’.
So, in Terminal, I type in :
iptables -A INPUT -s 192.168.0.6 -j DROP
This will drop all packets from the IP address after -s (for source IP). The IP here is my iPhone’s IP address. I use the Fing app on the iPhone to ping my machine after the iptables rule is activated and the packets are dropped, this is evident from the app returning the ‘unreachable’ message.
Now, to make the machine accept connections or packets from this IP address, all I have to do is delete this rule in the table. For this, I just change one character in the line as below. I would leave it for you to spot it and ponder the ‘why-hows’.
iptables -D INPUT -s 192.168.0.6 -j DROP
Now, I tried the ping from the same app on the iPhone and the machine was accepting connections.
While this is just a basic task, I would advise anyone interested in this area to explore and experiment more on iptables, its truly interesting!
Again, this is for my reference and also acting as my project journal. Feel free to ignore 😉
This post contains the chart with data from my ping flooding RTT’s on controllers OpenD, RYU and ONOS. Though I still have not been able to figure out the unpredictable OpenD behaviour as you may see from the chart, Excel has indeed helped me visualise and predict behaviour of these controllers. The Horizontal axes 1-5 are 10K,25K,50K,75K and 100K packet floods respectively.
This is a video that will motivate more and more youngsters to learn code and computers. This simple SSH ‘hack’ video (probably scripted but well played!) is definitely worth a watch. Go get your Raspberry Pi’s / VirtualBox/ VMware and get cracking!