Windows 7: The Default Gateway is not Available

I encountered a problem affecting a Windows 7 Ultimate (64-bit) system,  where the Internet connection was randomly disconnected, often while downloading a large file or streaming media across the network.  The Windows network troubleshooting wizard was able to correct the issue temporarily by performing a reset of the Network Adapter (Manually doing the same also restored connectivity).  Oddly enough,  the Local Area Network connection remained active,  but the Internet link was show as disconnected.  The network troubleshooting wizard identified the problem as being that the “Default Gateway was not available” even though the Broadband router was online and working fine for other computers.

After running some searches on the issue, I discovered that there were a large number of Windows 7 users who had been experiencing a similar problem.  The common factor was often the use of an NVidia NForce onboard network adapter,  however in this case the computer in question was using an Atheros 10/100/1000base-t controller (Onboard an ASUS motherboard).

The initial recommendation provided was that affected users should acquire updated NIC drivers from the manufacturer of their network card,  however there were no update drivers available for the Atheros card.

Luckily I came across information posted by a user suffering from the same problem on a similar system using the same onboard NIC (Atheros).  The recommendation that corrected the problem permanently was to:

Open Device Manager

Locate the Network Adapter

Right click, Properties

Go to Advanced tab

Locate the Task Offload (aka TCP offload) property on the list and set it to Disabled

After setting this property and applying the changes,  the Internet connection remained stable and no longer dropped out when transferring large amounts of data.

For more information see:
http://www.sevenforums.com/network-sharing/5787-problems-atheros-l1-ethernet-adapter-win7-x64.html
http://social.answers.microsoft.com/Forums/en-US/w7hardware/thread/59bcb7f5-fcca-44a4-b1db-787b1d269825

Scan a Network for Live IP Addresses (netping)

Ever come across a Linksys, Dlink, Netgear router or network printer that wasn’t documented and you have no idea what LAN IP was used so you can connect. This lightweght util does a great job scanning a network for live IPs on the wire:

http://www.codeplex.com/NetPing

 

Success Story of Our Proactive Server Support (PSS) Monitoring

Imagine it’s a quiet Saturday afternoon in the office. No week-day interruptions. You think to yourself, “This is going to be a very productive day.” Suddenly, you’re disconnected from the server, the Internet, the whole network!server overheat cartoon

You call your IT person on his cell phone.  Minutes into the call, your IT person asks you to hold as he has another call coming in. You wait patiently on hold for a minute and he clicks back over.  He informs you that the call was from Kazmarek Technology Solutions. They had received alerts that your network was down. And better yet, they will have an engineer right over to address the situation.

This true story happened a few weeks ago. The problem turned out to be a burnt out 24-port switch. We replaced the switch with a loaner switch from KTS and our client was back in business within 30 minutes.

KTS was able to respond quickly because the client subscribed to our Proactive Server Support, a proactive and preventative service we offer to keep your servers and networking equipment running optimally, as well as react quickly to issues with our 24/7 monitoring. 

Contact KTS today for more information on how you can keep your servers running smoothly with our Proactive Server Support.

See the rest of our latest newsletter here.


Don’t let this happen to your servers! 

 

 

 

 

 

Add SPF record to DNS

These days many mailservers are requiring reverse DNS (rDNS) and SPF records to validate the sender from this domain.

How does SPF work:

SPF is easy to understand. The “Internet” uses DNS (Domain Name System) to resolve Domain Names (as an example www.msexchange.org) into IP addresses. DNS is also used to direct requests for different services like e-mail and Web Servers. For every Domain around the world an MX (Mail Exchanger) record must exist. An MX record tells the e-mail sender where the target server for receiving mail is located.

SPF is publishing “reverse MX” records in DNS which tells the mail sender which machines send mail from the domain.

The recipient of the e-mail can now check these records to ensure that e-mail is coming from a “trusted” sender from this domain.

These “reverse MX” records can be easily published in DNS. It takes only one line in DNS to fullfil all requirements.

Microsoft has come up with a good and easy wizard (webpage not downloadable tool) that asks a few questions and spits out the correct SPF.

How to add SPF file to Windows Server DNS – link

OpenSPF Website – link or old site

Reset Snap Server Admin Password

The following procedure can be used on a Snap Server (tested with 2200) to reset the settings to factory defaults:

  1. Power off the Snap Server (wait for all lights to turn off).
  2. Hold down the reset button while powering the Snap Server on.  Wait for the System and Disk lights to flash in unison.
  3. Release the reset button.
  4. Press the reset button again according to the action you wish to perform:
    • Once to reset the IP address.
    • Twice to reset the Admin password (default is blank).
    • Three times to clear the network settings
    • Four times to clear all settings
    • Five times to initiate FLUP mode (for updates)
    • Six times to boot without mounting hard drives.
  5. Watch the disk light to confirm that it blinks the correct number of times to correspond with your selection.  If it doesnt, repeat step 4.
  6. Press and hold the reset button until the Snap Server resets.

DHCPLOC Utility – Detect Rogue DHCP Servers on your network

http://technet2.microsoft.com/windowsserver/en/library/8fa42e83-ec08-4a9b-9057-8909f7ed433e1033.mspx?mfr=true
This command-line tool displays the DHCP servers active on the subnet. If it detects any unauthorized DHCP servers, it beeps and sends out alert messages. It also displays packets that it detects from DHCP servers; you can specify whether to display packets from all DHCP servers or only those from unauthorized servers.

You can also use this tool to determine which DHCP servers are available to a DHCP client and to detect unauthorized DHCP servers on a subnet.

Here is the DHCPLOC syntax:

dhcploc /p /a:”AlertNameList” /i:AlertInterval ComputerIPAddress [ValidDHCPServerList]

/p suppresses display of detected packets from any of the authorized DHCP servers specified in ValidDHCPServerList. /a:”AlertNameList” sends alert messages to the names in AlertNameList if any unauthorized DHCP servers are found.

/i:AlertInterval specifies the alert frequency in seconds.

ComputerIPAddress specifies the IP address of the computer from which you are running DHCPLoc. If the computer has multiple adapters, you must specify the IP address of the adapter that is connected to the subnet you want to test.

ValidDHCPServerList specifies the IP addresses of any number of authorized DHCP servers. The tool does not send alerts when it detects packets from the servers in this list; however, it displays those packets unless you use the /p parameter.

Kazmarek Employees can find the utility on the KTS FTP server in the DownloadsMicrosoft Windows – ServerDHCPLoc location

Alternativily the utilty is available in the Support Tools directory on the Windows Server CD.

How to Use Netgear Wireless Routers as an AP

Netgear wireless routers can be used as an AP using the following supported method from Netgear:

http://kbserver.netgear.com/kb_web_files/n101496.asp

Default admin access password list for all makes and models of networking hardware

http://www.phenoelit.de/dpl/dpl.html