Mobile IPv4 secure firewall traversal with deployment of foreign agents

Currently mobile IP can enable mobile users to enjoy seamless roaming. However, if home networks are firewall-protected, mobile users can not access their home networks without successful authentication. So mobile users are out of contact with their home agents and then get lost to some extent. In this paper, we consider the case that, in mobile IPv4, a mobile node away from home obtains a care-of address from a foreign agent and communicates with its home agent and a correspondent node that are both behind the firewall of the home network. Our solution can achieve successful firewall traversal as well as end-to-end security by applying IPsec mechanisms on network entities. It does not require any modification of protocols and network entities. Besides, if foreign agents are deployed hierarchically, the security associations do not need to be renegotiated whenever a mobile node changes its network attachment point.