The Study of the VoIP through Firewall Security

Today Internet is very prosperous. Network firewalls have become basic network security equipments. Not only enterprises will set up firewall system, most of SOHOs and individual users also set up a firewall as a standard device. Because public IP is not sufficient in the IPv4-based environment, so most of networks are using NAT (Network Address Translation) mechanism to translation their private IP. Thus NAT also increases the complexity of VoIP (Voice over IP) through a firewall environment. In order to allow VoIP network environment in normal operation in a firewall environment, IETF and the VoIP industry propose a lot of solution. This article is going to present some common frameworks for analysis VoIP operation and looking forward to provide VoIP normally working in a firewall network environment.