IPS Intrusion prevention system P2P Peer-to-peer Malware Malicious software IDS Intrusion detection system VPN Virtual private network ACL access Control list HIPS Host-based IPS NIPS Network-based IPS TTL Time-to-live DoS Denial of service DDoS Distributed denial of service 入侵偵測系統 入侵防禦系統 資訊安全