Apt proxy configuration on Ubuntu 20.04 Focal Fossa Linux

You are reading a quick tutorial on how to configure apt proxy server and client on Ubuntu 20.04 Focal Fossa Linux

In this tutorial you will learn:

Software Requirements and Conventions Used

Software Requirements and Linux Command Line Conventions
Category	Requirements, Conventions or Software Version Used
System	Installed or upgraded Ubuntu 20.04 Focal Fossa
Software	N/A
Other	Privileged access to your Linux system as root or via the `sudo` command.
Conventions	# – requires given linux commands to be executed with root privileges either directly as a root user or by use of `sudo` command $ – requires given linux commands to be executed as a regular non-privileged user

By default the your new apt proxy server will deny any traffic from unknown hosts and this may result in the following error message 403 Access to cache prohibited .
To configure allowed hosts open the main apt cacher configuration file /etc/apt-cacher/apt-cacher.conf and uncomment the following line to allow any host to access apt-cacher’s resources:
```
allowed_hosts = *
```
Read the enclosed documentation regarding the allowed_hosts directive if the above configuration is to permissive for your environment.
Start and enable the proxy server to start after reboot:
```
$ sudo systemctl enable --now apt-cacher
```
Confirm that the apt proxy is up and running. The apt proxy server should be now listening on port3142:
```
$ ss -tl | grep 3142
LISTEN    0         128                0.0.0.0:3142              0.0.0.0:*
```
In case your Ubuntu system has firewall enabled, you will need to open a firewall port 3142 in order to allow incoming traffic:
```
$ sudo ufw allow from any to any port 3142 proto tcp
```

Using your apt-cacher proxy IP address or host name create a file eg. /etc/apt/apt.conf.d/30proxy with the following content while updating the IP address with the IP address of your apt-cacher server:
```
Acquire::http { Proxy "http://192.168.1.115:3142"; };
```
All is now ready and configured. Run apt command to confirm the apt cacher proxy configuration:
```
$ sudo apt udpate
```
If all went well check the content of the /var/cache/apt-cacher/ directory of your apt proxy server for new packages and updates.