Hello
My team is able to to build chat module like in freelancer site. We are experienced in CodeIgniter and other php frameworks like Zend, laravel, Symfony.
In area of web development our main specialization is LAMP stack of technologies (Linux, Apache, MySQL, PHP) but our developers have experience with Python, Node.js and Javascript ES6.
We have good knowledge in technologies requested in your project.
At this moment 50% of our business is Managed Services and 50% of our business is web development. That is why we are experienced in Linux and Plesk and AWS.
In area of providing Managed Services we have experience with such technologies as Virtuozzo, different types of virtualization (OpenVZ, KVM, XEN), different distributives of OS Linux / OS Unix / OS MS Windows Server systems, VPN/DNS/IPTables/Firewalls/web servers/mail servers configuration and tuning etc.
We provide a full range of Managed Networking Services, including System Administration, Technical Support of web servers and network equipment worldwide executed by our team of experts. In my team I have good Linux experts. Some of my Senior System Administrators are very known in open source community because they are maintainers of core one of the most popular Linux.
P.S. regarding all your requirements I hope you realize that such a project cannot cost 250 usd.
If you really need such a module - feel free to conatact us in a chat to discuss all the details.