Mar 21

Linux: Mounting file as a partition

Reading time: < 1 minute When we have a file with a 'dd' of a full disk and we want to mount a partition of that disk, we have to use an offset for jumping to the beginning of the partition that we want to mount. Using 'fdisk' command we can find the partitions of that disk copied inside a file.

Once partition table is shown there is a column called ‘Start’ using the corresponding number in this column for the partition that we want we can obtain the offset required for our mounting point. Reasoning behind that is multiply start sector per number of bytes per sector.

# OFFSET = START * 512
mount -o ro,loop,offset=OFFSET FILE_WITH_DISK_INSIDE /mnt

I hope thanks to this technical note next time that I forget how to get the offset I find it fastly.

Mar 07

socat tip: create virtual serial port and link it to TCP

Reading time: < 1 minute Create a virtual serial port and publish it on TCP port:

socat pty,link=/dev/virtualcom0,rawer tcp-listen:2101

In another computer, for instance, another virtual port can be created and connected to the previous one:

socat pty,link=/dev/virtualcom0,rawer tcp:SERVER_IP:2101

If in any of those both sides we want to open a real serial port, for instance, in the server case we can run:

socat /dev/ttyS0,rawer tcp-listen:2101

More information on socat manpage.

Jan 24

ngrok – service which solve services behind NAT issues

Reading time: < 1 minute This is another short entry, in this case for recommending a service which we solve typical problem solved using a DNAT. Once we have a service on our laptop, or on a private server and we have to expose that service on the internet for some time or permanently usually we have to go the firewall, or router and create a NAT rule forwarding a port. This is a simple and powerful service which is going to solve that for you. There is a free account for understanding and testing the service, other plans are available and especially affordable for professional requirements.

I was frogetting to say it’s compatible with Linux, Windows and Mac.

Nov 22

Python logger, quite interesting wrapper for python logging library

Reading time: < 1 minute Python logging library is really flexible and powerful but usually, you need some time for setting up the basics or just for logging in a simple script, some commands and settings have to be done. Daiquiri is a library which wrapper python logging library and offers a simple interface for start enjoying logging features in python. Next, there is a hello world example extracted from Daiquiri documentation which shows how easy it gets nice output from the console when you're programming simple scripts. daiquiri python library, hello world example


Nov 03

Google Chrome multiple profiles for productivity

Reading time: < 1 minute Hi everyone, some time ago Eloi gave a very good idea about how to use multiple profiles in Google Chrome for organizing different contents with different nature. And the most important thing, associate default Google accounts to the browser depending on those activities. Next video is a description of how I use that trick.

Oct 31

Three headphones until I get succeed

Reading time: 3 – 4 minutes

This is post entry is a summary of my experience with three different headphones until I found one which is compatible with Google Meet (professional version of Google Hangout). I spent a lot of hours every day working with video conference applications like Skype and others. It means stay sat for a long time, and when I don’t have to be in front of my screen I appreciate if I can walk around my room. Of course, this is only possible when the headphones that you use are wireless. A long time ago I had wired headphones and ended tired of having small incidents which damage my ears or drop off anything which was on my table.

So, I decided to read some benchmarks about high-quality headphones, I considered a tool for my job and I decided to spend my money. Having my requirements as a reference and using the benchmark readings for checking them I finally bought the Sennheiser PXC550. I’m not going to say whatever you can find in regular reviews, just some words to say this is a very good product with an excellent sound quality. But, not works with Google Meet (Hangout). What I mean is my voice it could not be understood by other peers. It’s impossible to understand anything. Using applications like Skype, or phone calls the quality was very good. Or using the headphones from my mobile phone and the Google Meet application the quality was good.

Thanks to Amazon guarantee I returned the product and I bought the Bose QuietComfort 35. Also a very good product, maybe a little bit worse than the Sennheiser one in some aspects but anyway a world-class product. Problems with Google Meet (Hangout) were even worst, in this case, sound quality was bad not only from my mic also other people of conversation had a really bad quality. Again with Skype, the quality was good. But when I connect the headphones to my mobile using Google Meet the sound quality was horrible, impossible to use.

Finally, I bought the Plantronics BackBeat PRO 2 SE. From those three that I tried this is the product with less quality IMHO. But Google Meet from my laptop works, my voice quality is not very good but it’s good enough for using them. Again I’m talking about a very good product, with a very good quality. In front of the other two, these ones are weighty, old fashion design, less comfortable, and worst sound quality. Some advantages that I found, the most important of course is it works with Google Meet (Hangout). The sound is louder at the maximum volume, and there are physical buttons for mute and on/off/pairing. Another advantage is the Bluetooth class 1 which give better coverage when I’m not next to the computer.

I didn’t say anything so far, but I’m talking always about Bluetooth connections with my laptop where I have a Windows 10 installed with Google Chrome. Laptop Bluetooth version is 4.0 HCI and LMP version: 6.1280 manufactured by Intel and driver version is 19.30.1646.853 (date: 2016-11-14).

If anybody knows a little bit more about this topic or wants to exchange any similar experience I’ll appreciate.