How to Configure an ISP with DHCP

Transcription

1 This article provides information on how to configure an ISP with DHCP and specify the settings for the DHCP client. You can configure up to six DHCP links on a Barracuda NG Firewall. In this article: Configure the DHCP Client To enable and configure a DHCP client: Log into the Barracuda NG Firewall. Open the Network page (Config > Full Config > Box > Network). From the Configuration menu in the left navigation pane, click xdsl/dhcp/isdn. Click Lock. From the DHCP Enabled list, select yes. In the DHCP Links table, click + to add an entry for your DHCP client. Enter a name for the entry and click OK. When you enter a name for the DHCP link, you can only use numbers and characters from the Latin character set, excluding special characters. 8. In the DHCP Links window, configure the link properties, connection, DNS servers, routes, and connection monitoring. For more information on the DHCP settings, see the following DHCP s section. 9. Click OK. 10. Click Send Changes and then click Activate. DHCP s The following sections provide more information on the settings that you can configure in the DHCP Links configuration window: Some of the settings are only available in advanced configuration mode. To access this mode, expand the Configuration Mode menu in the left navigation pane and then click Switch to Advanced. Link Properties Link Active Standby Mode DHCP Connect Timeout If set to yes, the link is taken into account for link management. Otherwise, it is ignored. To activate and monitor the link after network activation, select no. To activate and monitor the link externally, select yes. The timeout for connection attempts from the DHCP link to unreachable interfaces or networks. 1 / 5

2 Connection Details DHCP Interface MTU The Ethernet interface that is connected to the cable modem. This interface is reserved for exclusive use by the cable link. No other IP addresses or networks may reside on it. On the Control > Network page, the interface is renamed as dhcp. (Advanced Configuration Mode) The MTU. DNS Use Provider DNS Use Dynamic DNS Dynamic DNS Params To use the DNS servers assigned by your provider, select yes. To activate dynamic DNS, select yes. To use dynamic DNS, you must register with Verify with your provider if using dynamic DNS is advisable with a static address or an address that rarely changes. Note that when using static or rarely changing addresses, dynamic DNS might not be appropriate because the address must change once a month. Click Edit to configure dynamic DNS settings. In the Dynamic DNS Params window, you can configure the following settings: Service Type Select a dynamic DNS service type. You can select DynamicDNS (default), StaticDNS, or CustomDNS. For additional information about available DynDNS service types, see Dyndns Name The dynamic DNS name that was registered at dyndns.org. Secure Update To use HTTPS for updates, select yes. Otherwise, HTTP is used. User Access ID The user ID for accessing the server as defined during registration at dyndns.org. Access Password The password for accessing the server as defined during registration at dyndns.org. Wildcard Support To allow the resolution to sub-hostname (regardless of the domain, the IP address pointed to is the same), select yes. MX Record The mail handler (Mail exchanger) for the given domain. MXs are used for directing mail to other servers besides the one that the hostname points to. Backup MX To use the specified MX record as a backup mail server, select yes. The registered Dyndns Name is used as the primary mail server. To only use the specified MX record, select no. It is recommended that you do not use the MX settings offered. If you still choose to use the MX settings, see for detailed information. Retry Time [mins] After this length of time, the update is restarted if the previous attempt has failed. Routing Because routing is usually configured by the network subsystem itself, you only need to specify the target networks. If your default route should be set dynamically when the DHCP connection is established, then you can add /0 to the Target Networks table. When using backup routes that can be activated when another connection type fails, specify the route preference number in the Metric field. 2 / 5

3 Own Routing Table Use Assigned IP Source Networks Create Default Target Networks Advertise Trust Level Metric Clone s GRE with Assigned IP (Advanced Configuration Mode) To specify which networks should be routed through the DHCP interface, select yes and then specify the Source Networks. To route all traffic to the target networks through this interface, select no. If you select yes for this setting, you will only be able to select LCP as the monitoring method. (Advanced Configuration Mode) To use the the IP address dynamically assigned by your Internet provider as the source network for policy routing, select yes. Until the ISP has successfully assigned an address, the rule uses as a source address. You can only enable this setting when Own Routing Table is set to yes. (Advanced Configuration Mode) Use IP/mask notation when adding source networks. For a single host, enter 32 as its netmask (for example, /32). To automatically introduce the default route assigned by the provider, select yes. If the default route will be introduced in an environment where multiple dynamic links are available, you must specify a Metric. You must specify the target networks that will be reachable through the interface. (Advanced Configuration Mode) To advertise this route via dynamic routing protocols when the OSPF/RIP/BGP service is used, select yes. Specifies which IP address types are counted by the firewall for traffic on this interface. The interface can be classified as one of the following: Unclassified Trusted DMZ Untrusted Internal01 Internal02 The preference number assigned to this link in a multiprovider environment. (Advanced Configuration Mode) To clone the dynamic routes to the main or default table (depending on the route target), select yes. This setting is useful for setups where application-based selection (explicit binding in a firewall rule) of a traffic path is supposed to coexist with link failover (proxy dynamic). (Advanced Configuration Mode) To register the assigned IP address for IP protocol 47, select Yes. Connection Monitoring Log Level Reachable IPs Unreachable Action No. of ICMP Probes Waiting Period [s/probe] Check Interval [s] If you need verbose log files to troubleshoot any issues, select debug. In this table, add target IP addresses that will be regularly pinged to monitor the availability of the connection. You must enter least one single IP address that will be accessible only via the DHCP connection. Each IP address that you enter is pinged every 20 seconds (2 ICMP packets each). If none of the IP addresses respond, the link is deactivated. Then an attempt is made to re-establish the link. Select the action to be taken if the connection cannot be established. The following options are available: Restart Restarts the DHCP connection. Increase-Metric Changes the preference for DHCP routes until the probe succeeds. (Advanced Configuration Mode) The number of ICMP echo requests sent to each probing target IP address (maximum value: 9, default: 2). (Advanced Configuration Mode) The number of seconds per probe that a reply is waited for. (Advanced Configuration Mode) The time between link probes. 3 / 5

4 Failure Standoff [s] (Advanced Configuration Mode) The delay period before subsequent attempts to establish the link; this delay helps decrease the number of failed attempts to log. 4 / 5

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