Archive for the ‘Windows’ Category

How to backup Outlook Mailbox / Export Exchange Mail backup to .pst

Tuesday, November 17th, 2020

Reading Time: 3minutes


In the corporate world most of us are forced to use as a desktop environment some kind of Windows version 7 / 8 / 10  version with Outlook configured to use Microsoft Exchange MailServer mailbox set to use POP3 or IMAP account.
Sometimes for new employees for Knowledge transfer purposes having a backup copy of some employee who was laid off or as most of the times has left the company for a better position or simply due to boredom.

Even just for backup purposes in case if by mistake you have deleted some mails out of your mailbox it is useful thing to create a Mailbox backup of whole mail address data especially as with time the amount of Emails grows to many, many thousand of emails year by year and under some circumstances where you have a Mailbox data Limit to up to lets say 4 Gigabytes per mailbox it is useful to periodically clean up old mails, but for the historical reference to create a backup of old email.

Even at some times it is useful to create a whole backup of mailbox every year and then delete the content of Mail data for this year from Outlook.

Export of mail data in Outlook configured email is exported to .PST file format– [ MS-PST ]: Outlook Personal Folders.

Each Personal Folders File (.PST) represents a Message store that contains an arbitrary hierarchy of Folder objects, which contains Message objects, which can contain Attachment objects. Information about Folder objects, Message objects, and Attachment objects are stored in properties, which collectively contain all of the information about the particular item.

If you want to back up the message folders locally to work PC (in addition to keeping them on the Exchange server), you can automatically move or delete older items with AutoArchive (feature of Outlook) or export the items to .pst file that you can restore later as needed and use by importing.

So how to backup / export your Email correspondence to .PTS?

1. Select File -> Open & Export -> Import/Export


2. Select Export to a file, and then select Next.


3.Select Outlook Data File (.pst), and select Next.


4. Select the mail folder you want to back up and select Next.


5. Choose a location and name for your backup file, and then select Finish.


To ensure no one has access to your .pst files, after finish you'll be prompted to enter and confirm a password (or if you don't want pass leave pass field as empty), and then select OK.

The produced .pst file will be stored by default under C:\Users\Username\Documents\Outlook Files.

The messages that you keep in a .pst file are no different from other standard messages in outlook. You can forward, reply, or search through the stored messages as you do with other messages.

Set Domain multiple alias (Aliases) in IIS on Windows server howto

Saturday, October 24th, 2020

Reading Time: 4minutes

On Linux as mentioned in my previous article it is pretty easy to use the VirtualHost Apache directive etc. to create ServerName and ServerAlias but on IIS Domain multiple alias add too me a while to google.

<VirtualHost *>

In click and pray environments as Winblows, sometimes something rather easy to be done can be really annoying if you are not sure what to do and where to click and you have not passed some of the many cryptic microsoft offered ceritification programs offer for professional sysadmins, I'll name a few of them as to introduce UNIX guys like me to what you might ask a M$ admin during an interview if you want to check his 31337 Windows Sk!lls 🙂


  • Microsoft Certified Professional (MCP)
  • Microsoft Technology Associate (MTA) –
  • Microsoft Certified Solutions Expert (MCSE)-
  • Microsoft Specialist (MS) etc. –

A full list of Microsoft Certifed Professsional program here

Ok enough of  balling.

Here is  how to  create a domain alias in IIS on Windows server.

Login to your server and click on the START button then ‘Run’¦’, and then type ‘inetmgr.exe’.

Certainly you can go and click trough the Administrative tools section to start ISS manager, but for me this is fastest and easiest way.


Now expand the (local computer), then ‘Web Sites’ and locate the site for which you want to add alias (here it is called additional web site identification).

Right click on the domain and choose ‘Properties’ option at the bottom.

This will open the properties window where you have to choose ‘Web Site’ and then to locate ‘Website identification‘ section. Click on the ‘Advanced’¦’ button which stands next to the IP of the domain.

Advanced Web site identification window (Microsoft likes to see the word ‘Advanced’ in all of the management menus) will be opened, where we are going to add a new domain alias.


Click on the ‘Add’¦’ button and ‘Add/Edit website (alias)identification’ window will appear.


Make sure that you will choose the same IP address from the dropdown menu, then set the port number on which your web server is running (the default is 80), write the domain you want, and click ‘OK’ to create the new domain alias.

Actually click ‘OK’ until you have ‘Advanced Web site identification’ and the domain properties windows closed.

Right click on the domain again and ‘Stop’ and ‘Start’ the service.
This will be enough the IIS domain alias to start working.


Another useful thing for novice IIS admins that come from UNIX is a domain1 to domain2 redirect, this is done with writting an IIS rule which is an interesting but long topic for a limited post as like this, but just for the reference of fun to let you know this exist.

Domain 1 to Domain 2 Redirect
This rule comes handy when you change the name of your site or may be when you need to catch and alias and direct it to your main site. If the new and the old URLs share some elements, then you could just use this rule to have the matching pattern together with the redirect target being


That's all folks, if you enjoyed the clicking laziness you're ready to retrain yourself to become a successful lazy Windows admin who calls Microsoft Support everyday as many of the errors and problems Windows sysadmins experience as I heard from a friend can only be managed by M$ Support (if they can be managed at all). 

Yes that's it the great and wonderful life of the avarage sysadmin. Long live computing … it's great! Everyday something broken needs to get fixed everyday something to rethink / relearn / reupdate and restructure or migrate a never ending story of weirdness.

A remark to  make, the idea for this post is originated based on a task I had to do long time ago on IIS, the images and the description behind them are taking from a post originally written on Domain Aliasing in IIS originally written by Anthony Gee unfortunately his blog is not available anymore so credits goes to him.

How to restart Microsoft IIS with command via Windows command line

Friday, August 19th, 2011

Reading Time: < 1minute

I'm tuning a Windows 2003 for better performance and securing it against DoS of service attacks. After applying all the changes I needed to restart the WebServer for the new configurations to take effect.
As I'm not a GUI kind of guy I found it handy there is a fast command to restart the Microsoft Internet Information Server. The command to restart IIS is:

c:> iisreset

How to check Microsoft IIS webserver version

Monday, July 21st, 2014

Reading Time: 2minutes

If you have to tune some weirdly behaviour Microsoft IIS (Internet Information Services) webserver, the first thing to do is to collect information about the system you're dealing with – get version of installed Windows and check what kind of IIS version is running on the Windows server?

To get the version of installed Windows on the system you just logged in, the quickest way I use is:

Start -> My Computer (right mouse button) Properties


Run regedit from cmd.exe and go and check value of registry value:




As you can see in screenshot in this particular case it is IIS version 6.0.

An alternative way to check the IIS version in some cases (if IIS version return is not disabled) is to telnet to webserver:

telnet your-webserver 80

Once connected Send:


Also on some Windows versions it is possible to check IIS webserver version from Internet Information Services Management Cosnole:

To check IIS version from IIS Manager:

Start (button) -> Control Panel -> Administrative Tools -> "Internet Information Services" IIS Manager

From IIS Manager go to:

Help -> About Microsoft Management Console

Here is a list with most common IIS version output you will get depending on the version of Windows server:


Windows NT 3.51 1.0
Windows NT 4 2.0-4.0
Windows Server 2000 5.0
Windows XP Professional 5.1
Windows Server 2003 6.0
Windows Vista 7.0
Windows Server 2008 7.0
Windows Server 2008 R2 7.5
Windows 7 7.5
Windows Server 2012 8.0
Windows 8 8.0
Windows Server 2012 R2 8.5
Windows 8.1 8.5

If you have only an upload FTP access to a Folder served by IIS Webserver – i.e. no access to the Win server running IIS, you can also grasp the IIS version with following .ASP code:


Save the file as anyfile.asp somewhere in IIS docroot and invoke it in browser.

How to convert .CRT SSL Certificate to .PFX format (with openssl Linux command) and Import newly generated .PFX to Windows IIS Webserver

Tuesday, September 27th, 2016

Reading Time: 3minutes


1. Converting to .CRT to.PFX file format with OpenSSL tool on GNU / Linux to import in Windows (for example, IIS)

Assuming you have generated already a certificate using the openssl Linux command and you have issued the .CRT SSL Certificate issuer file
and you need to have the new .CRT SSL Certificate installed on Windows Server (lets say on Windows 2012) with IIS Webserver version 8.5, you will need a way to convert the .CRT file to .PFX, there is plenty of ways to do that including using online Web Site SSL Certificate converter or use a stand alone program on the Windows server or even use a simple perl / python / ruby script to do the conversion but anyways the best approach will be to convert the new .CRT file to IIS supported binary Certificate format .PFX on the same (Linux certificate issuer host where you have first generated the certificate issuer request .KEY (private key file used with third party certificate issuer such as Godaddy or Hostgator to receive the .CRT / PEM file).

Here is how to generate the .PFX file based on the .CRT file for an Internal SSL Certfiicate:


openssl pkcs12 -export -in server.crt -inkey server.key -out server.pfx

On the password prompt to appear use any password because otherwise the future IIS Webserver certificate import will not work.

To do a certificate chain SSL export to be accessed from the  internet.


openssl pkcs12 -export -in server.crt -inkey server.key -out server.pfx -certfile internet v2.crt

2. Import the PFX file in Windows

Run: mmc, add snap, Certificates, Computer account, Local Computer; in the

Certificates (Local Computer) > Personal > Certificates: Select All Tasks > Import File

Enter previously chosen password.
You should get further the Message "Import was successful."

You can import the PFX file by simply copying it to the server where you want it imported and double click it this will  open Windows Importwizzard.

Then select the IIS:


Site, Properties, Directory Security, Server Certificate, Replace the current certficate, select proper Certificate. Done.

Alternatively to complete the IIS Webserver certificate import within one step when a new certificate is to be imported:

In IIS Manager interface go to :

Site, Properties, Directory Security, Server Certificate, Server Certificate Wizard

Click on



import a certificate from a .pfx file, select and enter password.


3. Import the PFX file into a Java keystore

Another thing you might need if you have the IIS Webserver using a backend Java Virtual Machine on the same or a different Windows server is to import the newly generated .PFX file within the Java VM keystore.

To import with keytool command for Java 1.6 type:


keytool -importkeystore -deststorepass your_pass_here -destkeypass changeit -destkeystore keystore.jks -srckeystore server.pfx -srcstoretype PKCS12 -srcstorepass 1234 -srcalias 1 -destalias xyz

Also the .CRT file could be directly imported into the Java keystore


Import a .crt in a Java keystore

/usr/java/jre/bin/keytool -import -keystore /webdienste/java/jdk/jre/lib/security/cacerts -file certificate.crt -alias Some alias



4. Get a list of Windows locally installed certificates

To manager installed certificates on Windows 7 / 8 / 2012 Server OS is to run command via

Start -> Run





One other way to see the installed certificates on your Windows server is checking within

Internet Explorer

Go to Tools (Alt+X) → Internet Options → Content → Certificates.


To get a a complete list of installed Certificate Chain on Windows you can use PowerShell


Get-ChildItem -Recurse Cert:


That's all folks ! 🙂


Use multiple certificates using one IP address (same IP address) on IIS Windows web server

Saturday, October 24th, 2020

Reading Time: 3minutes

If you had to administer some Windows webservers based on IIS and you're coming from the Linux realm, it would be really confusing on how you can use a single IP address to have binded multiple domain certificates.

For those who have done it on linux, they know Apache and other webservers in recent versions support the configuration Directive of a Wildcard instead of IP through the SNI extension capble to capture in the header of the incoming SSL connection the exact domain and match it correctly against the domain with the respective certificate.  Below is what I mean, lets say you have a website called and you want this domain to be pointing to another location for example to

For example in Apache Webserver this is easily done by defining 2 separate virtualhost configuration files similar to below:


<Virtualhost *>


        SSLCertificateFile /etc/letsencrypt/live/
SSLCertificateKeyFile /etc/letsencrypt/live/



<Virtualhost *>



        SSLCertificateFile /etc/letsencrypt/live/
SSLCertificateKeyFile /etc/letsencrypt/live/


Unfortunately for those who still run legacy Windows servers  with IIS version 7 / 7.5 your only option is to use separate IP addresses (or ports, but not really acceptable for public facing sites) and to bind each site with it's SSL certificate to that IP address.

IIS ver. 8+ supports the Server Name Indication extension of TLS which will allow you to bind multiple SSL sites to the same IP address/port based on the host name. It will be transparent and the binding will work the same as with non-HTTPS sites.

In Microsoft IIS Webserver to configure, it is not possible to simply edit some configurations but you have to do it the clicking way as usually happen in Windows. thus you will need to have generated the Domain Certificate requests and so on and then you can simply do as pointed in below screenshots.







New World Order, Secret Societies and the Bible Prophecies a movie research on secret societies and Bible Prophecies

Monday, April 30th, 2012

Reading Time: 2minutes

I've just completed watching a movie I found on youtube


NWO: Secret Societies and Biblical Prophecy Vol. 1

The movie is quite intriguing research on the topic of Secret Societies and connection of what happened in the world so far. The movie points at what is about to happen in the future and how there are certain groups of people who has interest for the New Wolrd Order to come.


The movie says how the Biblical  Prophecies, we can read in the bible has clearly foretold many of the things that happened like the re-creation of  Jewish Country (Israel). All this events to occur was foretold many hundred years ago in the Holy Bible (scriptures). The movie director is called Leonard Ulrich a person who graduated with double degree in Winnepig University  and University of Minnetoba Caneda. This presentational material is as it the author points himself a 5 years of research on secret societies and the New Wolrd Order. The movie discuss the major secret societies (occult) organizations existing of today and claims there is a connection between the different secret societies. As Ulrich's point is there is a clear connection between the major globalism, secret societies and ancient occult teachings. The movie can be classified under a conspiracy theory and some of the facts might be considered by many sceptical people a wild imagination, however all those who  took the time to research on the movie's stand points will assure the movie is based on hard truths. As the presentation wents through history and turns back to the modern days it exposes how connections between a numerous of FreeMasonry organizations, dictatorship regimes like Communism, Nazism, Hitler Stalin and the rest of the key figures in modern day history somehow had a connection with the occult / sorceries / magicians  or secret societies. All the America Founders, communism, nazism and the world wars the author claims, were initiated by this same secret soecities. The movie reveals shocking facts about the United Nations  anti-christian character as well as the facts that many of the modern day turns the major world leaders of this day are orchestrated based on ancient non-christian belief systems like Kabalah  I will stop here with my review and let you alone watch it and discern if the facts in the movie can be considered trustable. For me personally as a Christian, I'm pretty much convinced what the movie retells is pure facts. Unfortunately nowdays, most people are so deluded, so they can't see the pure facts, but prefer to believe the lie that the world is governed towards its destination by money only.  Well, I clearly see it myself how most people nowdays are blindly led to bow down in front of technology which is just a major tool for the building of this unrightous (unjustice) system proclaimed under the fuzzy name New World Order. I truly enjoyed the movie and I believe watching the movie will help many to realize that Christianity is not just some old tales but a religion based on facts and truths.


Fix Blocked Unresponsive keyboard keys on Windows 7 / 10

Tuesday, February 25th, 2020

Reading Time: 5minutes



The Problem

If you're still using Windows 7 Operating system in your company due to some weird security concern policies and your company gets custom end user updates from Microsoft due to a special EULA agreement and you are new to using Windows E.g. have for many users used for your daily work Linux and Mac OS you might hit a strange issue wtih many of the keyboard keys strangely being locked with some of the keys such as Num Lock, Escape tab working where the Alphabet keys then don't panic. This is not a Windows bug its a feature (as usual) 🙂

Reason behind Blocked Unresponsive Keyboard


First logical thought I had is maybe my Logitech K120 Membrane 17 EURO cheap keyboard externally attached keyboard broke up thus I've tried to connect another LOGIC keyboard I had at hand just to assure myself the problem with partial keys on kbd reacting was present with the other Working keyboard as well.
This was an indicator that either the custom installed Windows by the company Helpdesk Office with the preassumed common additional features for corporations such as Keyloggers on this Laptop has messed up somohow the Windows service that is managing the keyboard or some kind of mechanical error or electronic circuit on the laptop embedded keyboard has occured or the KBD DLL Loaded driver damaged
I have to say here a colleague of mine was having a weird keyboard problems back in the day when I was still working in Project Services as a Web and Middleware in Hewlett Packard, where misteriously a character was added to his typed content just like a key on his keyboard has stuck and he experienced this issue for quite some time, he opened the keyboard to physically check whether all is okay and even checked the keyboard electricity whether levels on each of the keys and he couldn't find anything, and after running Malware Bytes anti-malware and a couple of other anti-malware programs which found his computer was infected with Malware and issue resolved.


Hard Fix – Reboot ..


As as a solution most times so far I've restarted the Windows which was reloading the Windows kernel / DLL libraries etc.

However just hit to this Windows accessibility feature once again today and since this is not the first time I end up with unworking keyboard (perhaps due to my often) furious fast typing – where I press sometimes multiple keys in parallel as a typing error then you trigger the Windows Disabled accessibiltiy Windows Feature, which as I thought makes the PC only usable for Mouse but unusuable for providing any meaningful keyboard input.

This problem I've faced already multiple times and usually the work around was the good known Windows User recipee phrase "Restart and It will get fixed", this time I was pissed off and didn't wanted to loose another 5 minutes in Restarting Reconnecting to the Company's Cisco Secure VPN reopening all my used files Notepad++ / Outlook / Browsers etc plus I was already part of online Lync (Skype) Meeting in which Colleague was Sharing his remote Desktop checking some important stuff about Zabbix Monitored AIX machine, hence didn't wanted to restart but still wanted to use my computer and type some stuff to send Email and do a simple googling.

Temporary work around to complete work with Virtual Keyboard

Hence as a temporary work around, I've used the Windows Virtual Keyboard, I've mentioned it in the earlier  blog post – How to run Virtual Keyboard in Windows XP / Vista article
To do so I'verun by typing osk command in cmd.exe command Prompt:

Either Search for osk.exe from Start menu


or run via command line via

Windows Button (on the Keyboard) + R and run

cmd.exe -> osk




Solution Without PC Restart

After a bit of thought and Googling I've found the fix  here

From the Start -> Control Panel from here I had to go to Accessibility Options.
Select Ease of Access Center.


Select the keyboard settings and
Ensure the following options are unchecked: Turn on Sticky Keys, Turn on Toggle Keys and Turn on Filter Keys.


I've found in the Turn on Toggle Keys tick present (e.g. service was enabled) – hence  after unticking it and 

Press Apply and OK, keyboard restored its usual functions.
Now all left was to  Enjoy as your keyboard was back usable and I could conitnue my Citrix sessions and SSH console Superputty terminals  and complete my started to write E-mail
without loosing time meanlessly for reboot.


Windows 10 Disable the Filter Keys option


This feature makes your keyboard ignore brief or repeated keystrokes, which might have led to your WinKey issue in Windows 10. To disable filter keys, use the instructions below:

1. Right-click on your Start menu icon.
2. Select Settings from the menu.
3. Navigate to Ease of Access and click on it.
4. Go to the left pane and click Keyboard.
5. Locate the Filter Keys feature.
6. Toggle it off.
7. Check if this manoeuvre has resolved your issue.

Closing Notes 

Of course this might be not always the fix, as sometimes it could be that the Winblows just blows your keyboard buffer due to some buggy application or a bug, but in most of the times that should solve it 🙂
If it didn't go through and debug all the other possible reasons, check whether you have a faulty keyboard cable (if you're still on a non-bluetooth Wired Keyboard), unplug and plug the keyboard again,
scan the computer for spyware and malware, rethink what really happened or what have you done until the problem occured and whether blocked keyboard is triggered by your user action or was triggered
by some third party software anti-virus stuff that did it as an attempt to prevent keylog sniffer / Virus or other weird stuff.

Check when Windows Active Directory user expires and set user password expire to Never

Thursday, January 9th, 2020

Reading Time: 4minutes


If you're working for a company that is following high security / PCI Security Standards and you're using m$ Windows OS that belongs to the domain it is useful to know when your user is set to expiry
to know how many days are left until you'll be forced to change your Windows AD password.
In this short article I'll explain how to check Windows AD last password set date / date expiry date and how you can list expiry dates for other users, finally will explain how to set your expiry date to Never
to get rid of annoying change password every 90 days.


1. Query domain Username for Password set / Password Expires set dates

To know this info you need to know the Password expiration date for Active Directory user account, to know it just open Command Line Prompt cmd.exe

And run command:


NET USER Your-User-Name /domain


Note that, many companies does only connect you to AD for security reason only on a VPN connect with something like Cisco AnyConnect Secure Mobility Client whatever VPN connect tool is used to encrypt the traffic between you and the corporate DMZ-ed network

Below is basic NET USER command usage args:

Net User Command Options

Item          Explanation

net user    Execute the net user command alone to show a very simple list of every user account, active or not, on the computer you're currently using.

username    This is the name of the user account, up to 20 characters long, that you want to make changes to, add, or remove. Using username with no other option will show detailed information about the user in the Command Prompt window.

password    Use the password option to modify an existing password or assign one when creating a new username. The minimum characters required can be viewed using the net accounts command. A maximum of 127 characters is allowed1.
*    You also have the option of using * in place of a password to force the entering of a password in the Command Prompt window after executing the net user command.

/add    Use the /add option to add a new username on the system.
options    See Additional Net User Command Options below for a complete list of available options to be used at this point when executing net user.

/domain    This switch forces net user to execute on the current domain controller instead of the local computer.

/delete    The /delete switch removes the specified username from the system.

/help    Use this switch to display detailed information about the net user command. Using this option is the same as using the net help command with net user: net help user.
/?    The standard help command switch also works with the net user command but only displays the basic command syntax. Executing net user without options is equal to using the /? switch.



2. Listing all Active Directory users last set date / never expires and expiration dates

If you have the respective Active Directory rights and you have the Remote Server Administration Tools for Windows (RSAT Tools), you are able to do also other interesting stuff,


such as

– using PowerShell to list all user last set dates, to do so use Open Power Shell and issue:

get-aduser -filter * -properties passwordlastset, passwordneverexpires |ft Name, passwordlastset, Passwordneverexpires


This should show you info as password last set date and whether password expiration is set for account.

– Using PS to get only the password expirations for all AD existing users is with:


Get-ADUser -filter {Enabled -eq $True -and PasswordNeverExpires -eq $False} –Properties "DisplayName", "msDS-UserPasswordExpiryTimeComputed" |
Select-Object -Property "Displayname",@{Name="ExpiryDate";Expression={[datetime]::FromFileTime($_."msDS-UserPasswordExpiryTimeComputed")}}

If you need the output data to get stored in CSV file delimitered format you can add to above PS commands



3. Setting a user password to never Expiry


If the user was created with NET USER command by default it will have been created to have a password expiration. 
However if you need to create new users for yourself (assuming you have the rights), with passwords that never expire on lets say Windows Server 2016 – (if you don't care about security so much), use:

NET USER "Username" /Add /Active:Yes

WMIC USERACCOUNT WHERE "Name='Username' SET PasswordExpires=False




To view the general password policies, type following:




How to clear ARP cache on Linux / Windows for a single IP address / Flush All IPs ARP cache

Wednesday, December 11th, 2019

Reading Time: 4minutes


On times of Public Internet IP migration or Local IPs between Linux servers or especially in clustered Linux Application Services running on environments like Pacemaker / Corosync / Heartbeat with services such as Haproxy.
Once an IP gets migrated due to complex network and firewall settings often the Migrated IP from Linux Server 1 (A) to Linux Server 2 (B) keeps time until a request to reload the Internet server IP ARP cache with to point to the new IP location, causing a disruption of accessibility to the Newly configured IP address on the new locations. I will not get much into details here what are the ARP (Address Resolution protocol) and Network ARP records on a Network attached Computer and how they correspond uniquely to each IP address assigned on Ethernet or Aliased network Interfaces (eth0 eth0:1 eth0:2) . But in this article, I'll briefly explain once IP Version 4 address is migrated from one server Data Center location to another DC, how the unique corresponding ARP record kept in OS system memory should be flushed in the ARP corresponding Operating System so called ARP table (of which you should think as a logical block in memory keeping a Map of where IP addresses are located physically on a Network recognized by the corresponding Unique MAC Address.

1. List the current ARP cache entries do

Arp is part of net-tools on Debian GNU / Linux and is also available and installed by default on virtually any Linux distribution Fedora / CentOS / RHEL / Ubuntu / Arch Linux and even m$ Windows NT / XP / 2000 / 10 / whatever, the only difference is Linux tool has a bit of more functionality and has a bit more complex use.
Easiest use of arp on GNU / Linux OS-es is.

# arp -an 

The -a lists all records and -n flag is here to omit IP resolving as some IPs are really slow to resolve and output of command could get lagged.

2. Delete one IP entry from the cache

Assuming only one IP address was migrated, if you want to delete the IP entry from local ARP table on any interface:

# arp -d

It is useful to delete an ARP cached entry for IP address only on a certain interface, to do so:

# /usr/sbin/arp -i eth1 -d


3. Create ARP entry MAC address with a static one for tightened security

A useful Hack is to (assign) / bind specific Static MAC addresses to be static in the ARP cache, this is very useful to improve security and fight an ARP poisoning attacks.
Doing so is pretty easy, to do so:

Above will staticly make IP to always appear in the ARP cache table to the MAC 00:50:ba:85:85:ca. So even if we have another system with the same MAC
trying to spoof our location and thus break our real record location for the Hostname in the network holding in reality the MAC 00:50:ba:85:85:ca, poisoning us
trying to make our host to recognize to a different address this will not happen as the static ARP will be kept unchanged in ARP caching table.


 # arp -s 00:50:ba:85:85:ca


4. Flush all ARP records only for specific Ethernet Interface

After the IP on interface was migrated run:


# ip link set arp off dev eth0 ; ip link set arp on dev eth0


5. Remove a set of few IPs only migrated ARP cache entries


# for i in; do sudo arp -d $i; done

Once old ARP entries are removed the arp command would return as:


linux:~$ arp
? ( at <incomplete>  on eth1
? ( at <incomplete>  on eth2

The / entry now shows as incomplete, which means the ARP entry will be refreshed when it is needed again, this would also depend
on the used network switches / firewalls in the network settings so often could take up to 1 minute or so..


6. Flush all ARP table records on Linux



# ip -s -s neigh flush all


7. Delete ARP Cache on FreeBSD and other BSDs

# arp -d -a 


8.  Flush arp cache on Windows

Run command prompt as Administrator -> (cmd.exe)  and do:

C:\> ipconfig /all
netsh interface ip delete arpcache


9. Monitoring the arp table

On servers with multiple IP addresses, where you expect a number of IP addresses migrated to change it is useful to use watch + arp like so:

# watch -n 0.1 'arp -an'

The -n 0.1 will make the arp -an be rerun every 10 miliseconds and by the way is a useful trick to monitor stuff returned by commands that needs a higher refresh frequency.


In short in this article, was explained how to list your arp cache table.The arp command is also available both on Linux and Windows) and as integral part of OS networking it is useful to check thoroghfully to its man page (man arp).
Explained was how to create Static ARP table records to prevent ARP poisoning attacks on a server.
I went through how to delete only a single ARP records (in case if) only certain IPs on a host are changed and an ARP cache entry reload is needed, as well as how to flush the complete set of ARP records need to get refreshed, sometimes useful on networks with Buggy Network Switches or when completely changing the set of IP-addresses assigned on a server host.