This is a simple setup guide to enabling Two Factor Authentication (2FA) on Linux SSH login. I this article I wont go deep into setup and issues that I have faced when implementing this. First thing is first Update your system first. I have used Ubuntu 20.04 and it is always up to date. To enable 2FA you need to install google authenticator modules sudo apt install libpam-google-authenticator Configuration for PAM and SSHD Add the the following line to /etc/pam.d/sshd and After adding this line please restart the sshd services. auth required pam_google_authenticator.so Go to /etc/ssh/sshd_config and check if the following line exist. Default value will be "no" so change it to "yes" to activate. ChallengeResponseAuthentication yes Configuration for Authenticator In the terminal run google authenticator command It will ask few things to acknowledge by user. Details you can see from the below video. Once this part is done you are ready to use the 2FA in ubuntu. T
Some of the GSM/GPRS chips do not support HTTP services and since the modems are controlled via AT commands, the AT command sets are very limited to HTTP commands in NEOWAY M590E.
The only option to communicate with any cloud based or locally hosted server was using TCP protocol. I have used HTTP services in many of my projects and experiments, it is easy and with few lines of code can manage an HTTP requests. For weeks i have been struggling with TCP request and every time it fails to connect or sometimes data is sent but from server side there is no new data fetched.
Basically TCP is transport layer in OSI model and HTTP is in application layer. TCP will do a socket based connection to servers predefined port. For example test.com:8989. what i mean is it needs a listener to listen to port that you define or open to use.
After weeks of reading articles and AT command sets thoroughly, finally i managed to handle a TCP request from modem. But still it fails sometimes or unable to connect to server ....blah blah..
The only option to communicate with any cloud based or locally hosted server was using TCP protocol. I have used HTTP services in many of my projects and experiments, it is easy and with few lines of code can manage an HTTP requests. For weeks i have been struggling with TCP request and every time it fails to connect or sometimes data is sent but from server side there is no new data fetched.
Basically TCP is transport layer in OSI model and HTTP is in application layer. TCP will do a socket based connection to servers predefined port. For example test.com:8989. what i mean is it needs a listener to listen to port that you define or open to use.
After weeks of reading articles and AT command sets thoroughly, finally i managed to handle a TCP request from modem. But still it fails sometimes or unable to connect to server ....blah blah..
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| NEOWAY M590E chip connected to microcontroller |
Finally figured out a way to send the commands with error checking and if fails it will retry the steps again until it is successful. The following AT commands are used for NEOWAY chips and for different vendors AT command sets are different so if you are trying TCP request flow that i have used in here please bare that in your mind. :P
at+xisp=0
at+cgdcont=1,"IP","your APN"
at+xiic=1
at+tcpsetup=1,server-address,port
at+tcpsend=1,number of chars
> --- when this prompt comes up, you can send the data.
GET /test.html HTTP1.1
HOST:server-address,port
Connection:keep-alive
CTRL+Z ---once the data is loaded..send termination command to send data
at+tcpclose=1 --- disconnect IP connection
AT+CGATT=0 --- disconnect GPRS connection
I send all these commands from micro controller and mean time watching for prompts and error handling. Timing is very important to send the command and get the results back.
I have posted a video of how my code is handling the errors.
Please subscribe to my YouTube channel and Instagram. A very special thanks to Andrea's for supporting me.
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