| 摘要 |
The invention provides a transmission system, for example, an ATM transmission system, which is adapted for the transmission of IP data packets, and which includes an IP-network, a network protected by a firewall, and means for temporarily opening the firewall to enable IP data packets to be transmitted through the firewall to the protected network. The firewall operates in a manner whereby a particular type of IP-packet, i.e. a Ping (ICMP)-packet, is allowed to pass through the firewall, IP-traffic can pass through the firewall from the inside thereof to the outside thereof, and IP-traffic, similar to that which is sent from the inside of the firewall to the outside of the firewall, can be transmitted through the firewall to the protected network for a limited period of time. In particular, the firewall opening means include two IC-breakers, which are located on opposite sides of said firewall, and which have a structure and functionality dictated by the manner in which the firewall operates. In other words, when an IP data packet, destined for the protected networks, is received by the IC-breaker located on the outside of the firewall, the IC-breakers are adapted to communicate with each other to create the temporary opening in the firewall via which the IP data packet is sent to the protected network. |
