How to redirect the work of all applications through a proxy in xubuntu?

Question

linux

Greetings! Please tell me how you can pass absolutely everything through the specified system proxies?
Based on a couple of tickets, I followed the instructions, but the same Firefox, without instructions to use system proxies, connects directly, not to mention any terminal applications. Thanks for the help!
askubuntu.com/questions/150210/how-do-i-set-system...
superuser.com/questions/357688/how-to-configure-pr...