firejail

$ firejail [application] [options]

Eg. Firefox

$ firejail firefox --net=eth0 # suppose we have a default interface named eth0

• --net=eth0:

Restrict network access to the eth0 interface. To allow this option for regular (non-root) users, we have to comment out the restricted-network yes line in the /etc/firejail/firejail.config file:

# Restricted networking grants access to --interface, --net=ethXXX and --netfilter only to root user. Regular users are only allowed --net=none
restricted-network yes # comment out this line to remove the restrictions for regular users

Suppose we have a simple web server running on localhost port 8888:

$ python3 -m http.server 8888

Usually, accessing http://localhost:8888 from the web browser will return the directory listing from which the server is running. However, if we supply the option --net=eth0 to the firejail command when running the web browser (eg. firefox), the access will be blocked, and we will receive an error when trying to access the address.

This is because we access the localhost address via the loopback (lo) interface, which has not been allowed.

Examples

1. Safe document viewer

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