The present invention discloses a network security system including a firewall arranged between the internal network and the external network, and a trusted node arranged between the firewall and the external network, which is used to provide a data channel between the internal network and the external network, and forward the data transported between the internal network and the external network; the firewall includes a first port configured at the internal network oriented side of the firewall and a second port configured at the external network oriented side of the firewall; and the trusted node includes a media-stream receiving port used to converge the data from the second port. The present invention also discloses a network security method.