Anmol Sharma

Friendica Ldap not working

Anmol Sharma

Thu, 19 Nov 2020 03:51:11 -0800

@Friendica Support (Friendica Support)
I am trying to debug the Ldap issue for Friendica Yunohost package. This is the reason the PR for latest release in still pending.
The ldap plugin seems to be enable on fresh install. But something in Authentication.php is not working the way it use to be.
Here is the log for a ldap user tying to login.

[WARNING]: authenticate: failed login attempt {"action":"login","username":"anmol@yolo.test","ip":"10.61.111.1"} - {"file":"Authentication.php","line":272,"function":"withPassword","uid":"6d2315","process_id":14968}

Server Yunohost

Friendica Support

Thu, 19 Nov 2020 03:51:13 -0800

🔁 Repeated @Anmol Sharma's Note

Comparing two float values in shell

Anmol Sharma

Thu, 12 Nov 2020 17:14:10 -0800 last edited: Sun, 22 Nov 2020 09:36:38 -0800

Comparing the two integers in shell works as expected. But working with float is difficult. We get error if we try to compare float values in normal if statement. Here is a work around to compare the float values in shell.

#!/bin/bash
version=5.0.0
var=$(awk 'BEGIN{ print "'$version'"<"'5.0.0'" }') 
if  [ "$var" -eq 1 ]; then
        echo "true"
fi

#shell #script #server

Server How-To Shell

Installing Linux inside Linux

Anmol Sharma

Fri, 06 Nov 2020 11:34:48 -0800 last edited: Fri, 06 Nov 2020 12:08:45 -0800

Chroot and installing Debian inside base Linux

Installing a Linux inside a Linux and giving the access through ssh to a user and providing some services through the main server is a very specific requirement, an interesting one to have in your admin skills.

I assume you will be installing an app my_webapp__1 through Yunohost that gives a empty container for PHP use. But if you want try this on normal Debian system, then you must have an web server installed like Nginx, Apache etc. A folder and user with user having access to that folder. Lastly a ssh server to connect remotely.
If your installation is ready go to step 2. Assume my_webapp__1 as your folder and user. Change the names according to your configurations.

Install my_webapp on yunohost.

# yunohost app install https://github.com/YunoHost-Apps/my_webapp_ynh/

Remove force sftp for the app from ssh
```
# nano /etc/ssh/sshd_config
```
Remove
```
ForceCommand internal-sftp
```
from the my_webapp__1 or the what ever your my_webapp instance number is.
Allow the user to have ssh permission by adding the line
```
AllowUsers  my_webapp__1
```
Restart ssh
```
# service ssh restart
```
Install debootstrap. Read more about chroot and debootstrap here
```
# apt-get install debootstrap
```

Install the choice of os in chroot directory.

# debootstrap stable /var/www/my_webapp__1 http://deb.debian.org/debian/

You can login to the root of the new installed os by chroot
```
# chroot /var/www/my_webapp__1
```
Install the required packages like ssh,sudo
```
# apt-get install ssh sudo
```
Exit the chroot
```
# exit
```
The uid of users should be same for both users in the real os and the chroot os. So we put the real os uid of the my_webapp1 user to the chroot my_webapp1 after creating it.
```
# cat  /etc/passwd
```
Check the uid of the my_webapp__1 and copy it.
Again login to chroot directory by step 7 and create a user my_webapp__1 in chroot OS.
```
# adduser my_webapp__1
```
Give it the same password as real OS user.
Make the uid of the real os same with the chroot os by coping the uid of real os to chroot os.
```
 # nano  /etc/passwd
```
Copy the uid to the my_webapp__2
Now you can ssh to the chroot folder with the my_webapp__1 user.

Try it

$ ssh my_webapp__1@domain.tld

Enter password and you will be in the shell as my_webapp__1 user of chroot os.

Sometimes the my_webapp1 will require root privileges. For this either you can give my_webapp2 as root privileges or login as root by su. Other way is giving user privilege to run sudo without password and with root access by editing /etc/sudoers.
Login to the chroot root by step 7 again and add the user to have sudo privieges.

# nano /etc/sudoers

Add this line under Allow members of group sudo to execute any command

my_webapp__1 ALL=(ALL) NOPASSWD: ALL

Now you can ssh to the chroot by ssh my_webapp__1@domain.tld and run any command which require by sudo.

#server #Yunohot #ssh #Debian #chroot #debootstrap #linux

Server Yunohost how-to

Domain redirects in Nginx

Anmol Sharma

Fri, 30 Oct 2020 09:55:06 -0700

There are situations when you want to redirect a domain to other domain for various reasons like your site is hosted on example.com and you want www.example.com to go to example.com where your site is or you may have a landing page which you want to point from many other domains for advertisement. This can be done through Nginx by redirecting the domain or sub-domain to that particular site.

Edit the below file by nano or vim:

$ nano /etc/nginx/conf.d/www.example.com.conf

Add the following code inside it.

location / 
{
      return 301 $scheme://example.com$request_uri;
}

Now the www.example.com will be redirected to example.com.

#nginx #server #domain

Nginx Server

Grab the bounced emails

Anmol Sharma

Wed, 21 Oct 2020 06:00:16 -0700

There maybe times when someone would send an email to your server with wrong address which would bounce. As an system admin you should keep a track of these wrong mails and map them with probably correct mail address. This will help your users to get important emails which they otherwise would have missed.

Here is the grep command which gets the email address of the bounced address sent to your server.

$ grep 'User unknown in virtual mailbox table' /var/log/mail.log | sed -e 's/.*to=<//g' | sed -e 's/>.*//g' | sort -t: -u -k1,1

Your configuration maybe different, so may require to do little changes to it.
#mails #server #logs

Mails Logs Server How-To