Category Archives: Networking

Linux WiFi manual setup

You might have faced to have your laptop that doesn’t boot with your nice GUI interface, with Network Manager that handles your wifi connection. Maybe due to a failed update or a broken package.

Well, it happened to me exactly for that reason: some issues with an upgrade. And how can you fix a broken package or dependency without internet connection?

Oooh yes, that’s a nightmare! Thankfully, I found this handy article, which I will list some handy commands, that did help me in restoring the connection on my laptop, allowing me to fix the upgrade and restore its functionality.

NOTE: I had iwconfig and wpasupplicant already installed. If not, I should have downloaded the packages and all their dependencies and manually install them with dpkg -i command

Identify what’s the name of your wifi interface

iwconfig

This should return something like wlp4s0

Guessing that you know already the SSID (e.g. HomeFancyWiFi) of your wifi and the password (e.g. myWiFiPassw0rd), you can run directly this command:

wpa_passphrase HomeFancyWiFi myWiFiPassw0rd | sudo tee /etc/wpa_supplicant.conf
wpa_supplicant -c /etc/wpa_supplicant.conf -i wlp4s0

This will generate the config file, connect to the wifi. Once you see that all works as expected, you could use the -B flag to put the wpa_suppicant in background and release the terminal.

wpa_supplicant -B -c /etc/wpa_supplicant.conf -i wlp4s0

Alternatively, you can move to another tab (ALT+F1,F2,F3… in the text mode console), and run dhcpclient to get an IP and the DNS set.

dhclient wlp4s0

Once done, you can run iwconfig just to verify that the interface has the IP and do some basic network troubleshooting like ping etc to make sure all works, and you can go back to fix your broken upgrade ūüôā

Ubuntu 16.04 – Wake on LAN

I have struggled a bit trying to understand while my Ubuntu 16.04 wasn’t waking up with the common¬† etherwake¬† commad.

I found the solution on this link:

you should disable Default option in Network-Manager GUI and enable only the Magic option. If you try this, then you should check if everything is ok opening the shell and issuing this command:

You should see the line:

If it’s not¬†g¬†but¬†d¬†or something else, something could be wrong.

Once done that, and verified with the command¬† ethtool <myNetinterface> | grep "Wake-on:"¬†, all started to work again ūüôā

 

Bridge / Bond interfaces CentOS/RedHat

Just few notes about how to bridge or bond network interfaces in CentOS/RedHat systems

 

Sources:

Linux Firewall notes

IPTABLES GENERIC

 


UBUNTU – UFW

https://help.ubuntu.com/community/UFW

 


CENTOS / RH – Firewalld

Saved rules in: /etc/sysconfig/iptables

 

Remote port forwarding via SSH

Imagine that you¬†want to access a specific port on a remote server from your local machine. Basically, a “remote port forwarding”.

This remote server is not accessible directly from internet. It is NAT’d behind firewall.
To access the remote server you need to connect firstly to a remote bastion server (accessible from internet) and from there, you will be able to access the server.
Your current machine is also within restricted network and unable to ssh out. You can ssh into a local bastion server only. From this local bastion you can ssh out.

As long as you have access to the 2 bastions servers, you will be able to run the following script.

The script points/links a local_port on your local machine to the ssh port of the remote bastion, via your local bastion.
After that, it will connect the remote port or the remote server to a new_local_port, ssh’ing via local_port.

Example below shows a way to have the VNC port 5900 available locally on port 5910.
I’m using port 8888 as local port.
Local Bastion ssh port is 8022.
Remote Bastion ssh port is 9022.

Example:

 

And here a full script:

 

Physically restart Sky router via Raspberry Pi

I have a Sky Hub router, the SR102 (black). Previously I had the white version as well.
Nice routers, pretty stable, but badly locked. You can change the SID of your wifi, change the password… not either sure if you can do a proper port forwarding. So… perfect for my mum,¬†but a pain for whoever wants a little bit of extra control.

I had already an ASUS RT-N16 with DD-WRT firmware¬†so I used the DMZ function on the Sky router to have some sort of “link” of the public IP of my broadband directly on the WAN interface of the router. In this way it’s like that is my ASUS router that does the connection and I can play as freely as I want, without caring much about the Sky router.

However, it happens that sometimes you need to give a full reboot to the main Sky router. And maybe do this automatically or via command line/script. And here it’s when things are getting more complicated.

The Sky Hub router allows you to reboot it via HTTP. Using the DMZ anyway will bypass the router itself and forward all the requests to the ASUS router. Also, I have never liked the idea to expose my router management page to the Internet, but I rather prefer to connect via SSH on a Raspberry Pi and issue commands from the terminal (telnet/ssh).

So, beside my multiple attempts to find a way to curl the button on the page, I had to find an alternative way to makes this happen. Of course, it didn’t help either to call the Sky Helpline asking if there was a remote possibility to have telnet enabled.

After a bit of talks on Facebook with some friends, here the solution: Remote Controlled Sockets with Pi-mote

Yes. If I can’t reboot from¬†inside, let’s to that from¬†outside!

The process was pretty straight forward.

First of all, I had to turn off my Raspberry Pi, and plug the¬†“little green piece of board” as mentioned in here

After that, I’ve turned the pi on again, and installed the required packages. Happily I found that there is now the python library available for¬†energenie, so I have installed them as well, making my life easier ūüôā

Once done, I have created these two basic script and I have run one a time, to configure the socket plugs.

Make sure to plug the ONE SOCKET PLUG A TIME and run the relative script.

You can find more information in the previous PDF, but these sockets learn who they are based on which commands they are receiving during the learning mode (enabling keeping the green button pressed for about 5 seconds when switched off). So if you run the first script with both plugs connected and in learning mode, they will do exactly the same, and unless you want to control two sockets at the same time, better to follow the instructions ūüôā

Script to configure the first socket:

 

Script to configure the second socket:

 

And now, my simple script to make… “the magic”: plugs.py

You can use this script to control any sockets (up to 4 – hardware limitation).

And here a bash wrapper (I’m not really good in python sorry) that calls plugs.py and restart the router:¬†restart_sky_router

 

Now, I can have my Nagios system to check for the speed as documented here and eventually issue restart_sky_router script to see if it fixes the issue. Or simply be able to have a command to integrate in your scripts!

 

Disable firewalld – Centos 7

Install iptables and remove firewalld

Banana Pi Pro – WLAN configuration

Add ‘ap6210‘ to /etc/modules to enable WiFi, and use modprobe ap6210 to force load the module.

Check dmesg to see if all has been loaded correctly. If not, reboot and check again.

Install the required packages:

Modify /etc/network/interfaces

Bring the interface up:

Source: http://oyox.de/882-wlan-auf-bananian-banana-pi-einrichten/