How does traceroute work?

It uses the TTL (Time To Live) parameter and UDP to get the path. Each router which is passed needs to decrease the TTL value of a packet and if it is below 1 the router will discard it and send a ICMP (time exceeded) back to the source. So traceroute sends the first packet with a TTL of 1 to reach the first router and one more with a TTL of 2 to reach the second and so on. You get the picture. But how does it know when the destination is reached? Well it useses another trick for that.  Traceroute sends out a UDP Packet with it with a port higher than 3000. It is very unlikely that this port will be opened at the destination so it will get back from the destination a ICMP packet (port unreachable) which is the answer to the question.

Important: Remember that not all packets are going the same way and it’s likely that they use different paths.

admin on June 27th 2013 in IT, Network

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Scam Email: URGENT: “company name” Brand Registration Confirmation!

This is a scam mail where they tell you that somebody is trying to register your domain name with another topleveldomain. If  you answer to it you will probably bid against an imaginary company which doesn’t exist and get an expensive domain name or even just loose the money.  Of course if you ask who wants to buy it they won’t tell you because of privacy issues.

Email Content:

(Please forward to the President or Brand Owner, thank you)

Dear Sir/Madam,
We are a registration agency of Asian Domain Registration Organization in China. I have something to confirm with you. We formally received an application on June 17, 2013 that a company which self-styled "Abtry International Co.,Ltd" were applying to register "company name" as their Brand Name and some domain names through our firm.

Now we are handling this registration, and after our initial checking, we found these names were similar to your company’s, so we need to check with you whether your company has authorized that company to register these names. If you authorized this, we will finish the registration at once. If you did not authorize, please let us know within 7 workdays, so that we will handle this issue better. Out of the time limit we will unconditionally finish the registration for "Abtry International Co.,Ltd". Looking forward to your prompt reply.

Best Regards

Hannah Lin

admin on June 19th 2013 in Email, IT

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Migrate Printers from Windows 2008 to 2012 with Powershell

It is possible to export all printers from Windows 2008 Server and import them again into Windows 2012. I tried this method but got just error messages and I didn’t like the fact, that it imports also the old drivers. So I installed first the necessary printer drivers on the new server and run the script below to create all the printers. It automatically adds the necessary ports and the printers. If you want to add more parameters it is easily possible.

Create CSV file with the printers (printers.csv):
Name, IP, Driver, Location
"PRINTER01", "192.168.1.10", "Xerox Global Print Driver PCL6", "Main Building, First Floor"
"PRINTER02", "192.168.1.11", "Xerox Global Print Driver PCL6", "Main Building, Second Floor"

Script to import the printers (printers.ps1):
$printers = Import-Csv c:\temp\powershell\printers.csv
 
foreach ($printer in $printers) {
    Add-PrinterPort -Name $printer.Name -PrinterHostAddress $printer.IP
    Add-Printer -Name $printer.Name -DriverName $printer.Driver -PortName $printer.Name -Comment $printer.Comment -ShareName $printer.Name
    Set-printer -Name $printer.Name -Shared $true -Published $true
}

admin on June 6th 2013 in IT, Windows Server

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Install SNMP with Powershell on Windows 2012

If you run the command without the management tools then you won’t have the tabs to configure the snmp-service. By the way the argument –Whatif shows you in advance what would be installed if you run the command. So to actually installe it run the command without –WhatIf.

#Add-WindowsFeature -Name SNMP-Service -IncludeAllSubFeature -IncludeManagementTools –Restart –WhatIf

admin on June 4th 2013 in IT, PowerShell, Windows Server

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Debugging: Install/Deinstall Services within Visual Studio

To run a service you actually need to compile it and install it with InstallUtil.exe. To make this process faster you can easily add this function to Visual Studio.
Go to “Tools\External Tools….” and add following:

image

Title
Install Service

Command
C:\Windows\Microsoft.NET\Framework\v4.0.30319\InstallUtil.exe

Arguments
$(TargetPath)

Initial directory
$(TargetDir)

Use Output Window
Should be selected

To uninstall the service Add following:

Title
Uninstall Service

Arguments
/u $(TargetPath)

Initial directory
$(TargetDir)

Use Output Window
Should be selected

admin on May 31st 2013 in .Net, IT

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Enable Settings to be able to manage a Windows Server 2012 Core

Powershell
Enable-PSRemoting –Force

Tests
Test-WSMan –ComputerName [Computer]
Enter-PSSession –ComputerName [Computer]

Manage via Server Manager
Configure-SMRemoting.exe –Enable

MMC
Enable-NetFirewallRule –DisplayGroup “Windows Remote Management”

Remote Desktop
cscript C:\Windows\System32\Scregedit.wsf /ar 0

or just conifgure it via sconfig

Tests
Run from another machine mstsc and connect to the server.

admin on May 2nd 2013 in Windows Server

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See who is logged into a computer remotly and how to log off from a remote computer

With this query you get a list of all logged on users:
quser /SERVER:servername

Pick the ID from above to log off the user:
logoff 2 /SERVER:servername

admin on April 22nd 2013 in IT, Windows, Windows Server

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Install Active Directory from a media to save initial replication time

If you need to setup Active Directory on another location and you don’t much bandwith you can install it from a media.

On the source AD create the files to copy to the media:
#ntdsutil
#activate instance ntds
#ifm

#create rodc c:\temp
For a Read Only Domain Controller

#create full c:\temp
For a Standard Domain Controller
#quit
#quit

Check the files and copy it to a media. On the new DC you can choose the files for the first replication

admin on March 6th 2013 in IT, Windows Server

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How to upgrade from Windows 2012 Standard to Data Center

Run following command with your Data Center Key:
DISM /Online /Set-Edition:ServerDatacenter /AcceptEula /ProductKey: YOUR_PRODUCT_KEY

admin on March 6th 2013 in IT, Windows Server

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How to access/edit Active Directory Schema

regsvr32 schmmgmt.dll
mmc
Add Snapin Schema

admin on March 5th 2013 in IT, Windows Server

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