ZyXEL Communications G.SHDSL.bis 4-port Security Gateway P-793H - Manual (Page 15)

P-793H User’s Guide
Table of Contents 15
9.4 Connection Direction ........................................................................................133
9.4.1 LAN to WAN Rules .................................................................................134
9.4.2 Alerts .......................................................................................................134
9.5 Triangle Route ..................................................................................................134
9.5.1 The “Triangle Route” Problem ................................................................134
9.5.2 Solving the “Triangle Route” Problem .....................................................135
9.6 General Firewall Policy ....................................................................................136
9.7 Firewall Rules Summary .................................................................................137
9.7.1 Configuring Firewall Rules ....................................................................138
9.7.2 Customized Services .............................................................................141
9.7.3 Configuring A Customized Service ........................................................141
9.8 Example Firewall Rule .....................................................................................142
9.9 Anti-Probing .....................................................................................................146
9.10 DoS Thresholds ............................................................................................147
9.10.1 Threshold Values ..................................................................................147
9.10.2 Half-Open Sessions ..............................................................................148
9.10.2.1 TCP Maximum Incomplete and Blocking Time ...........................148
9.10.3 Configuring Firewall Thresholds ...........................................................149
Chapter 10
Content Filtering .................................................................................................. 151
10.1 Content Filtering Overview ............................................................................151
10.2 Configuring Keyword Blocking .......................................................................151
10.3 Configuring the Schedule ..............................................................................152
10.4 Configuring Trusted Computers ....................................................................153
Chapter 11
IPSec VPN ............................................................................................................. 155
11.1 IPSec VPN Overview .....................................................................................155
11.1.1 IKE SA Overview ..................................................................................156
11.1.1.1 IP Addresses of the ZyXEL Device and Remote IPSec Router ..156
11.1.1.2 IKE SA Proposal ..........................................................................157
11.1.1.3 Diffie-Hellman (DH) Key Exchange .............................................157
11.1.1.4 Authentication ..............................................................................158
11.1.2 Additional Topics for IKE SA .................................................................159
11.1.2.1 Negotiation Mode ........................................................................159
11.1.2.2 VPN, NAT and NAT Traversal .....................................................160
11.1.3 IPSec SA Overview ...............................................................................160
11.1.3.1 Local Network and Remote Network ...........................................161
11.1.3.2 Active Protocol .............................................................................161
11.1.3.3 Encapsulation ..............................................................................161
11.1.3.4 IPSec SA Proposal and Perfect Forward Secrecy ......................162
11.1.4 Additional Topics for IPSec SA .............................................................162