Telegram is a very amazing messaging application focus in speed and security, Many active contributors in the Fedora project use it for the daily work and fun. basically this motivate me for use it:

Telegram has several features like the next:

  • Free (of charge, no ads)
  • Secure (side-to-side and storage encryption)
  • Open source
  • Have a clear API
  • It is multiplatform
  • Timer for message destruction (very good for dirty chats ( : )
  • and more, please check the official page for more info.

For install it in fedora we have at least three client options:

Official desktop client:

This client is not in the Fedora repos but exists the CORP from Rommon, so we need enable it and install the client:

$ sudo dnf copr enable rommon/telegram
$ sudo dnf install telegram-desktop

Know Issue: The first time telegram is executed it will generate (at least in KDE) a second desktop entry. It can be delete with the menu manager, make sure you delete the right one.

Cutegram:

Just like its name says, it is cute 😛

$ sudo dnf install cutegram

CLI Client:

For hardcore, cli geeks

$ sudo dnf install telegram-cli

Enjoy

Reading the always awesome Fedora Magazine, I discovered the Hack Font, just take a look:

this beautiful font is not ready in the fedora official repos but we can install it using the corp repo (Thanks a lot Heliocastro),

We can add the repo and install with dnf as follows:

$ sudo dnf copr enable heliocastro/hack-fonts
$ sudo dnf install hack-fonts

Or simply add the repo and install:

# cat > /etc/yum.repos.d/hack-fonts.repo
[heliocastro-hack-fonts]
name=Copr repo for hack-fonts owned by heliocastro
baseurl=https://copr-be.cloud.fedoraproject.org/results/heliocastro/hack-fonts/fedora-$releasever-$basearch/
type=rpm-md
skip_if_unavailable=True
gpgcheck=1
gpgkey=https://copr-be.cloud.fedoraproject.org/results/heliocastro/hack-fonts/pubkey.gpg
repo_gpgcheck=0
enabled=1
enabled_metadata=1
(Now CTRL+D)
# dnf install hack-fonts

Configure your favorite terminal emulator to use it and enjoy:

 

Cheers 🙂

Still we have the ugly openssl-1.0.0 dependency in fedora for the cisco packettracer network simulato,

Here the rpm, if you have i686 version or want compile your version (best security and because i don’t provide any warranty) check this post

 

Fedora Version RPM
23 http://bt0.ninja/rpm/openssl-lib-compat-1.0.0i-1.fc23.x86_64.rpm
24 http://bt0.ninja/rpm/openssl-lib-compat-1.0.0i-1.fc24.x86_64.rpm
25 http://bt0.ninja/rpm/openssl-lib-compat-1.0.0i-1.fc25.x86_64.rpm

I want update this list if necessary or by request

Cheers.

Cisco Packet Tracer 7.0 is created by Cisco SystemsTM and is now provided for free distribution. Self learners are now able to download Cisco Packet Tracer after registering on Cisco Netacad website. A free Packet Tracer 101 (English), a 1-hour self-paced online course is also offered to every registered (free) student to help them get started with PacketTracer 7.0, So you can register and download from here.

The cisco packettracer 7.0 is available for GNU/Linux under the next requirements:

  • nss and ssl libraries.
  • QT4 script-tools, WebKit and QT3 backward support.
  • Cisco NetSpace account. (Mandatory)

We need install some libraries as follows:

$ sudo dnf install zlib-devel ncurses-devel gtk2 glibc glibc-devel \\
 libstdc++ libX11-devel libXrender libXrandr libusb libXtst nss \\
 qt qtwebkit

This time we have x86 (32bits) and x86_64(64bits) Packet Tracer packages, to be sure what is our version, run:

$ uname -m

i686 (32bits)

Still we have the ugly openssl-1.0.0 dependency, so if we have a i686 (32bits) version of Fedora 25:

$ wget  http://www.deltaeridani.com/openssl-lib-compat-1.0.0i-1.fc25.i686.rpm
$ sudo rpm -Uvh openssl-lib-compat-1.0.0i-1.fc25.i686.rpm

x86_64 (64bits)

Today most people have a x86_64 machine and this time we have two options for resolve the OpenSSL dependency:

1.- Just download the package generated by me and simply trust me (I call this the ugliest method because i don’t provide any warranty):

$ wget  http://bt0.ninja/rpm/openssl-lib-compat-1.0.0i-1.fc25.x86_64.rpm
$ sudo rpm -Uvh openssl-lib-compat-1.0.0i-1.fc25.x86_64.rpm

2.- Compile your own version (I call the “just ugly” method because you can check the source):

First get the code:

$ wget http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/17/Everything/source/SRPMS/o/openssl-1.0.0i-1.fc17.src.rpm
$ sudo dnf install @development-tools fedora-packager krb5-devel
$ sudo rpm -Uvh openssl-1.0.0i-1.fc17.src.rpm

For the build process we need super user access:

$ su -
# cd rpmbuild/SPECS/
# wget http://bt0.ninja/rpm/openssl-lib-compat-1.0.0.spec
# rpmbuild -bb openssl-lib-compat-1.0.0.spec
# rpm -i ../RPMS/x86_64/openssl-lib-compat-1.0.0i-1.fc25.x86_64.rpm
# exit

So many thanks to Yves L’ECUYER owner of http://www.deltaeridani.com, the original spec and the example are all from him.

Cisco Packet Tracer 7.0 will be downloaded from Cisco Networking Academy Portal,

$ tar -xzf PacketTracer70_linux.tar.gz && cd PacketTracer70
$ chmod +x install
$ sudo ./install

After accept the EULA, the installation begins, we need set the environment variables with the next command:

$ sudo /opt/pt/set_ptenv.sh

Graphical Launcher on Gnome

At this point packettracer is ready to use but another useful thing to do is create a desktop Cisco Packet Tracer icon to launch it, first download the icon:

$ wget http://upload.wikimedia.org/wikipedia/en/d/dc/Cisco_Packet_Tracer_Icon.png
$ sudo mv Cisco_Packet_Tracer_Icon.png /usr/share/icons/

With our favorite plain text editor we will create the file /usr/share/applications/packettracer.desktop as follows:

[Desktop Entry]
Encoding=UTF-8
Name= PacketTracer 7.0 Comment=Networking Cisco GenericName=Cisco PacketTracer 7 Type=Application Exec=/opt/pt/packettracer Icon=/usr/share/icons/Cisco_Packet_Tracer_Icon.png Categories=Education; StartupNotify=true

Now we will run Cisco Packet Tracer 7.0 from our Desktop:

cheers!!!

Hello everyone,

Today I read about the problem with one assertion in systemd, I read it in the amazing blog of Andrew Ayer (Click here), Right now is necessary document this problem using the Proof of Concept published in the systemd github page.

For documentation purposes I use screenshots but the final report for the systemd bug tracking is in plain text :).

screenshot-from-2016-09-29-10-35-05

screenshot-from-2016-09-29-10-40-08

 

screenshot-from-2016-09-29-10-44-46

The calls to systemd based commands (systemd-nspaw, systemctl, etc) hangs and later shows a timeout message. No general system degradation.

Ok, Andrew Ayer has a very clever point but my opinion is better help to debugging and improve systemd.

Cheers.

 

Note: For Fedora 25 see this post http://www.bt0.ninja/packettracer-7-0-in-fedora-25/

Note: For Fedora 26 see this post http://www.bt0.ninja/packettracer-7-in-fedora-26

Note: For Fedora 27 see this post http://www.bt0.ninja/cisco-packettracer-7-1-on-fedora-27

Cisco Packet Tracer 7.0 is created by Cisco SystemsTM and is now provided for free distribution. Self learners are now able to download Cisco Packet Tracer after registering on Cisco Netacad website. A free Packet Tracer 101 (English), a 1-hour self-paced online course is also offered to every registered (free) student to help them get started with Pracer 7.0, So you can register and download from here.

The cisco packettracer 7.0 is available for GNU/Linux under the next requirements:

  • nss and ssl libraries.
  • QT4 script-tools, WebKit  and QT3 backward support.
  • Cisco NetSpace account. (Mandatory)

We need install some libraries as follows:

$ sudo dnf install zlib-devel ncurses-devel gtk2 glibc glibc-devel \\
 libstdc++ libX11-devel libXrender libXrandr libusb libXtst nss \\
 qt qtwebkit

This time we have x86 (32bits) and x86_64(64bits) Packet Tracer packages, to be sure what is our version, run:

$ uname -m

i686 (32bits)

Still we have the ugly openssl-1.0.0 dependency, so if we have a i686 (32bits) version of Fedora 24:

$ wget  http://www.deltaeridani.com/openssl-lib-compat-1.0.0i-1.fc24.i686.rpm
$ sudo rpm -Uvh openssl-lib-compat-1.0.0i-1.fc24.i686.rpm

x86_64 (64bits)

Today most people have a x86_64 machine and this time we have two options for resolve the OpenSSL dependency:

1.- Just download the package generated by me and simply trust me  (I call this the ugliest method because i don’t provide any warranty):

$ wget  http://bt0.ninja/rpm/openssl-lib-compat-1.0.0i-1.fc24.x86_64.rpm
$ sudo rpm -Uvh openssl-lib-compat-1.0.0i-1.fc24.x86_64.rpm

2.- Compile your own version (I call the “just ugly” method because you can check the source):

First get the code:

$ wget http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/17/Everything/source/SRPMS/o/openssl-1.0.0i-1.fc17.src.rpm
$ sudo dnf install @development-tools fedora-packager krb5-devel
$ sudo rpm -Uvh openssl-1.0.0i-1.fc17.src.rpm

For the build process we need super user access:

$ su -
# cd rpmbuild/SPECS/
# wget http://bt0.ninja/rpm/openssl-lib-compat-1.0.0.spec
# rpmbuild -bb openssl-lib-compat-1.0.0.spec
# rpm -i ../RPMS/x86_64/openssl-lib-compat-1.0.0i-1.fc24.x86_64.rpm
# exit

So many thanks to Yves L’ECUYER owner of http://www.deltaeridani.com, the original spec and the example are all from him.

Cisco Packet Tracer 7.0 will be downloaded from Cisco Networking Academy Portal,

$ tar -xzf PacketTracer70_linux.tar.gz && cd PacketTracer70
$ chmod +x install
$ sudo ./install

After accept the EULA, the installation begins, we need set the environment variables with the next command:

$ sudo /opt/pt/set_ptenv.sh

Graphical Launcher on Gnome

At this point packettracer is ready to use but another useful thing to do is create a desktop Cisco Packet Tracer icon to launch it, first download the icon:

$ wget http://upload.wikimedia.org/wikipedia/en/d/dc/Cisco_Packet_Tracer_Icon.png
$ sudo mv Cisco_Packet_Tracer_Icon.png /usr/share/icons/

With our favorite plain text editor we will create the file /usr/share/applications/packettracer.desktop as follows:

[Desktop Entry]
Encoding=UTF-8
Name= PacketTracer 7.0 Comment=Networking Cisco GenericName=Cisco PacketTracer 7 Type=Application Exec=/opt/pt/packettracer Icon=/usr/share/icons/Cisco_Packet_Tracer_Icon.png Categories=Education; StartupNotify=true

Now we will run Cisco Packet Tracer 7.0 from our Desktop:

Screenshot from 2016-08-04 10-43-19 Screenshot from 2016-08-04 10-43-35

cheers!!!

systemd is a system and service manager for Linux.It is (retro) compatible with systemV and LSB init scripts. It is relatively new but has been widely accepted by major Linux distributions.

Frankly, at first,  I did not like it,  I saw it too complex, bulky and don’t see any shell script on the service management, but remembering the wisdom of  Master Foo Discourses on the Two Paths, i give it one opportunity and I just fell in love.

I’ll outline a few things that I find awesome about systemd, In no particular order:

1.- It don’t use Shell scripts

Ok it is not clear but systemd is faster and scale better in bootup, when we use scripts they call many times commands like grep, awk, cd, ls and others, so this execution is slow (but easy to hack).

2.-Use the units concept

One unit is a file than encodes information about a service (.service),a mount point (.mount),a device(.device), a socket (.socket), a timer (.timer) and other abstract entities, we can enable, disable, start, stop , restart, mask units. See   man systemd.unit for details.

$ sudo systemctl start unit
$ sudo systemctl stop unit
$ sudo systemctl enable unit
$ sudo systemctl disable unit

3.- We can check the system state

Just with this commands:

$ systemctl status

and list running and failed units

$ systemctl list-units
$ systemctl --failed

4.- It is hotplug capable

systemd assumes that all resources may appear and dissapear at any time, this is one of the reasons because systemd depends of dbus but right now, our systems become dynamic systems with lowest downtime when adding or removing hardware.

5.- It is modular

All of what is now rc.sysinit is split out into many independent services, each of which is well documented and easy to understand.

6.- Can deploy containers with systemd-nspawn

I talk about it in this post.

7.- The systemd timers

Timers have built-in support for calendar time events, monotonic time events, and can be run asynchronously.Timers Timers can be used as an alternative to CRON and “at command”  but timers have a more complex syntax than crontab entries but our duty as sysadmins is learn it.

8.- systemd is a cross-distro project

Every major and many, many minor distros have had people contributing to systemd, it is the default in Debian 8, Fedora, OpenSuse, Ubuntu (Leaving Upstart for systemd) and many many others distros use systemd.

9.- systemd do power management

You can poweroff, restart, suspend or hibernate using systemd. (for unprivileged users you need polkit)

$ sudo systemctl poweroff
$ sudo systemctl reboot
$ sudo systemctl suspend
$ sudo systemctl hibernate

10.- Have a build-in logging system

systemd has its own logging system called the journal; therefore, running a syslog daemon is no longer required. To read the log, use:

# journalctl

The systemd journal event notification message logging classification corresponds to classical BSD syslog protocol style (RFC 5424).

For more information about systemd:

Cheers!!!