Yes, you can not only access firewall from your
VPS server, it is even possible to make changes when you want to do it. Many users do configure IP tables rules to secure the server the way they want and add to the level of security of their business. Remember, one of the key features of VPS hosting services is that it gives you root access to your virtual private space which enables to make use of the resources the way you want to for optimizing results. The same feature allows you to access firewalls and make your system more secure.