Protocol-independent settings | D-Link DFL-700 instruction

Protocol-independent settings

Allow ICMP errors from the destination to the source – ICMP error messages are sent in several situations: for example, when an IP packet cannot reach its destination. The purpose of these error control messages is to provide feedback about problems in the communication environment.

However, ICMP error messages and firewalls are usually not a very good combination; the ICMP error messages are initiated at the destination host (or a device within the path to the destination) and sent to the originating host. The result is that the ICMP error message will be interpreted by the firewall as a new connection and dropped, if not explicitly allowed by the firewall rule-set. Now, allowing any inbound ICMP message to be able have those error messages forwarded is generally not a good idea.

To solve this problem, DFL-700 can be instructed to pass an ICMP error message only if it is related to an existing connection. Check this option to enable this feature for connections using this service.

ALG – Like other stateful inspection based firewalls, DFL-700 filters on information found in packet headers, for instance in IP, TCP, UDP and ICMP headers.

In some situations though, filtering on header data only is not sufficient. The FTP protocol, for instance, includes IP address and port information in the protocol payload. In these cases, the firewall needs to be able to examine the payload data and carry out appropriate actions. DFL-700 provides this functionality using Application Layer Gateways, also known as ALGs.

To use an Application Layer Gateway, the appropriate Application Layer Gateway definition is selected in the dropdown menu. The selected Application Layer Gateway will thus manage network traffic that matches the policy using this service.

Currently, DFL-700 supports two Application Layer Gateways, one is used to manage the FTP protocol and the other one is a HTTP Content Filtering ALG. For detailed information about how to configure the HTTP Application Layer Gateway, please see the Content Filtering chapter.

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D-Link DFL-700 manual Protocol-independent settings

Contents

Link DFL-700 Contents Firewall Servers Status 129 132 Introduction Features and BenefitsAccess Control supported Introduction to Firewalls Introduction to Local Area Networking LEDs Physical Connections Package Contents System Requirements Resetting the DFL700 Managing D-Link DFL-700 Administration Settings Administrative Access Add ping access to an interface Add Admin access to an interface Add Read-only access to an interface Enable Snmp access to an interface Interfaces SystemChange IP of the LAN or DMZ interface WAN Interface Settings Using Dhcp WAN Interface Settings Using Static IPIP Address The IP address of the WAN interface. This is WAN Interface Settings Using PPPoE Password WAN Interface Settings Using Pptp Password The password supplied to you by your ISP WAN Interface Settings Using BigPondTraffic Shaping MTU Configuration Routing Remove a Static Route Add a new Static RouteGo to System and Routing Logging Enable Audit Logging Enable LoggingEnable E-mail alerting for ISD/IDP events Page Time Changing time zone Using NTP to sync timeSetting time and date manually Checking the Set the system time box Policy modes FirewallPolicy Action Types Schedule Service FilterSource and Destination Filter Intrusion Detection / Prevention Traffic Shaping Add a new policy Enable the Intrusion Detection / Prevention checkbox Configure Intrusion DetectionEnable the Delete policy checkbox Change order of policy Configure Intrusion Prevention Port mapping / Virtual Servers Add a new mapping Enable the Delete mapping checkbox Delete mapping Administrative users Add Administrative User Change Administrative User Password Change Administrative User Access levelEnable the Change password checkbox Delete Administrative User Enable the Delete user checkbox Users DFL-700 Radius Support Enable User Authentication via Http / Https Enable Radius Support Change User Password Add User Delete User Schedules Add new recurring schedule Services Adding TCP, UDP or TCP/UDP Service Grouping Services Adding IP Protocol Protocol-independent settings VPN Introduction to IPsec Introduction to L2TP Introduction to PptpPoint-to-Point Protocol Authentication Protocols MPPE, Microsoft Point-To-Point Encryption Authentication protocol L2TP/PPTP Clients Authentication Protocol Introduction chapter L2TP/PPTP Servers Mppe encryption VPN between two networks Creating a LAN-to-LAN IPSec VPN Tunnel VPN between client and an internal network Creating a Roaming Users IPSec VPN Tunnel Adding a L2TP/PPTP VPN Client Adding a L2TP/PPTP VPN Server VPN Advanced Settings IKE Proposal List Proposal ListsIPSec Proposal List Local identities CertificatesTrusting Certificates Certificates of remote peers Certificate Authorities Identities Content Filtering Active content handling Edit the URL Global Whitelist Edit the URL Global Blacklist Active content handling Dhcp Server Settings Servers Disable Dhcp Server/Relayer Enable Dhcp ServerEnable Dhcp Relay Enable by checking the Use built-in Dhcp Server box Enable DNS Relayer DNS Relayer SettingsEnable by checking the Enable DNS Relayer box Disable DNS Relayer Ping ToolsPing Example Add Dynamic DNS Settings Dynamic DNS Exporting the DFL-700’s Configuration BackupRestoring the DFL-700’s Configuration Restoring system settings to factory defaults Restart/ResetRestarting the DFL-700 Page Upgrade Firmware UpgradeUpgrade IDS Signature-database System StatusCPU Load Interfaces VPN Connections Dhcp Server Users Drop events How to read the logsUsage events Conn events Open Example Close Example Step by step guides LAN IP 192.168.4.1, Subnet mask LAN-to-LAN VPN using IPsecLocal net 192.168.4.0/24 Enable Automatically add a route for the remote network Remote Net 192.168.1.0/24 LAN IP 192.168.1.1, Subnet mask Local net 192.168.1.0/24 Remote Net 192.168.4.0/24 LAN-to-LAN VPN using Pptp Username BranchOffice Click Activate and wait for the firewall to restart Settings for Main office Page Select Local database Under Users in local database click Add newPage LAN-to-LAN VPN using L2TP Username BranchOffice Check Use IPsec encryption Settings for Main office Page Select Local database Under Users in local database click Add new More secure LAN-to-LAN VPN solution Page Page Settings for Main office Settings for the Windows XP client Windows XP client and Pptp server Select Connect to the network at my workplace and click Next Select Virtual Private Network connection and click Next Name the connection MainOffice and click Next 108 Select Do not dial the initial connection and click Next Page Click Properties Page Setup interfaces, System-Interfaces WAN IP193.0.2.20 Page Windows XP client and L2TP server 116 Settings for Main office Page Content filtering Firewall-Services Select HTTP/HTML Content Filtering in the ALG dropdownPage Page Intrusion detection and prevention Page Check Enable E-mail alerting for IDS/IDP events Limit bandwidth to a service Traffic shaping Guarantee bandwidth to a service Page Appendixes Appendix a Icmp Types and CodesPage Appendix B Common IP Protocol Numbers ESP Limited Warranty What Is Not Covered Wichtige Sicherheitshinweise Advertencia de Marca de la CE CE Mark WarningWarnung Attenzione Vcci Warning Offices 138 Page 140