Event ID 1107 — DHCP Server Rogue Detection

Applies To: Windows Server 2008

When configured correctly and authorized for use on a network, Dynamic Host Configuration Protocol (DHCP) servers provide a useful administrative service. However, a misconfigured or unauthorized DHCP server can cause problems. For example, if an unauthorized DHCP server starts, it might begin either leasing incorrect IP addresses to clients or negatively acknowledging DHCP clients that attempt to renew current address leases.

To resolve these issues, DHCP servers are verified as authorized in Active Directory Domain Services before they can service clients and unauthorized, or rogue, servers are detected. This prevents most of the accidental damage caused by either misconfigured DHCP servers or correctly configured DHCP servers running on the wrong network.

Event Details

Resolve

Identify and fix any network connectivity problems

To resolve this issue, identify and fix any network connectivity problems between the‚  DHCP server and domain controller by doing the following:

• Determine if there is a network connectivity problem by using the ping command.
• Perform additional troubleshooting steps, if necessary, to help identify the cause of the problem.

To perform these tasks, refer to the following sections.

Note: The following procedures include steps for using the ping command to perform troubleshooting. Therefore, before performing these steps, check whether the firewall or Internet Protocol security (IPsec) settings on your network allow Internet Control Message Protocol (ICMP) traffic. ICMP is the TCP/IP protocol that is used by the ping command.

To perform these procedures, you must have membership in the local Administrators group, or you must have been delegated the appropriate authority.

Determine if there is a network connectivity problem

To determine if there is a network connectivity problem between the‚  DHCP‚  server and domain controller:

1. At the DHCP server, click Start, click Run, type cmd, and then click OK.
2. At the command prompt, type ping server_FQDN, where server_FQDN is the fully qualified domain name (FQDN) of the domain controller (for example, server1.contoso.com), and then press ENTER.

If the ping was successful, you will receive a reply similar to the following:

Reply from IP_address: bytes=32 time=3ms TTL=59

Reply from IP_address: bytes=32 time=20ms TTL=59

Reply from IP_address: bytes=32 time=3ms TTL=59

Reply from IP_address: bytes=32 time=6ms TTL=59

1. At the command prompt, type ping IP_address, where IP_address is the IP address of the domain controller, and then press ENTER.

If you can successfully ping the domain controller by IP address, but not by FQDN, this indicates a possible issue with DNS host name resolution.

If you cannot successfully ping the domain controller by IP address, this indicates a possible issue with network connectivity, firewall configuration, or IPsec configuration.

Perform additional troubleshooting steps

The following are some additional troubleshooting steps that you can perform to help identify the root cause of the problem:

• Ping other computers on the network to help determine the extent of the network connectivity issue.
• If you can ping other servers but not the domain controller, try to ping the domain controller from another computer. If you cannot ping the domain controller from any computer, first ensure that the domain controller is running. If the domain controller is running, check the network settings on the domain controller.
• Check the TCP/IP settings on the local computer by doing the following:

1. Click Start, click Run, type cmd, and then click OK.
2. At the command prompt, type ipconfig /all, and then press ENTER. Make sure that the information listed is correct.
3. Type ping localhost to verify that TCP/IP is installed and correctly configured on the local computer. If the ping is unsuccessful, this may indicate a corrupt TCP/IP stack or a problem with your network adapter.
4. Type ping IP_address, where IP_address is the IP address assigned to the computer. If you can ping the localhost address but not the local address, there may be an issue with the routing table or with the network adapter driver.
5. Type ping DNS_server, where DNS_server is the IP address assigned to the DNS server. If there is more than one DNS server on your network, you should ping each one. If you cannot ping the DNS servers, this indicates a potential problem with the DNS servers, or with the network between the computer and the DNS servers.
6. If the domain controller is on a different subnet, try to ping the default gateway. If you cannot ping the default gateway, this might indicate a problem with the network adapter, the router or gateway device, cabling, or other connectivity hardware.

• In Device Manager, check the status of the network adapter. To open Device Manager, click Start, click Run, type devmgmt.msc, and then click OK.
• Check network connectivity indicator lights on the computer and at the hub or router. Check network cabling.
• Check firewall settings by using the Windows Firewall with Advanced Security snap-in.
• Check IPsec settings by using the IP Security Policy Management snap-in.

Verify

To perform these procedures, you must be a member of the Administrators group, or you must have been delegated the appropriate authority.

To verify that the DHCP server is authorized in Active Directory Domain Services, perform the following steps:

1. At the DHCP server computer, click Start, click Run, type dhcpmgmt.msc, and then press ENTER.
2. Right-click DHCP, and then click Manage authorized servers.
3. If the DHCP server is authorized, it appears in the list.

To verify that clients are getting leased IP addresses from the DHCP server, perform the following steps:

1. At the DHCP-enabled client computer, click Start, in Start Search type cmd, and then press ENTER.
2. To verify the lease of the client with a DHCP server, type ipconfig /all to view lease-status information.
3. The DHCP server should be distributing leases to clients.

Related Management Information

DHCP Server Rogue Detection

DHCP Infrastructure