Network

Tech Short: How To Change The MTU – Server 2016

 

Troubleshooting an application issues which could possibly be network related.  I found myself needing to make some adjustment to the maximum transmission unit (MTU) setting of my server.  As such what better time to post a quick technical short on how to go about doing this.

 

How To Change The MTU – Windows Server 2016

Requirements:

  • Logon and Administrator permission on Server
  • Network Connectivity
  • Time to reboot

 

Procedure:

From the desktop of your Windows Server 2016 server open an Administrative command prompt by Right-Clicking on the start button and select  – Command Prompt (Admin).

Once in the command prompt you we be using netsh to determine the IDX of the installed interface devices. this is performed by using the following command:  netsh interface ipv4 show interfaces

Take note of the IDX interface that you would like to change the MTU on as this is what we need to specify when changing the MTU settings.

Using netsh again you issue the following command: netsh interface ipv4 set subinterface “number-goes-here” mtu=1400 store=persistent

Please note that the subinerface will be the IDX number from the first netsh command and that the MTU setting is a value less than the original 1500.

Now you can reboot to have the changes take effect.  I have also noticed the disabling the interface and  re-enabling also works.

 

 

Disable Windows Firewall Server Core

Server Core now installed and what is the first command I choose to run in PowerShell

Its a command to disable all firewall profiles:

 

TechShort: PowerShell to Setup VPN Connections

Here is a way we can be consistent with our setup of VPN connections on computers.

Using PowerShell this is made simple with a small script on a USB stick, network share or whatever method you choose to get the to the client machine

The following is a one line PowerShell command:

Next is to see if this can be placed in a group policy to have it automated on end user computers

I hope this helps your process of machine setups.

– Jermal

Ref: https://technet.microsoft.com/en-us/%5Clibrary/JJ554820(v=WPS.630).aspx

ET P2P Torrent Client User-Agent (Solid Core/0.82)

I have been seeing this alert “ET P2P Torrent Client User-Agent (Solid Core/0.82)” on networks for sometime now and was able to narrow it down to being related to Adobe Flash (Firefox and Chrome). I am not sure why Adobe is using a torrent client in its flash but this seems to be the source.

This is also triggered not only by updating the software, but from the web installer when it connects out.

I later confirmed this myself with the assistance of another who updated their flash and triggered this alert.

 

I hope you enjoyed this post
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Some Basic Use of Nmap

Nmap (“Network Mapper”) is a free and open source utility for network discovery and security auditing. I along with many other systems and network administrators also find it to be a useful tool for the right job. Nmap can be installed and used in Windows, and mostly common in Linux distributions such as Debian and the well known Ubuntu.

You can get the Windows install form http://nmap.org/ along with the Linux versions.  In Linux (Debian) I simple sudo apt-get install nmap -y and the rest is done in a few seconds.

Now that you have Nmap, what can you do? Here are some examples I use every so often:

~# nmap google.com – gives me info about google.com (Hostname google.com resolves to 11 IPs..)

~# nmap 192.168.1.0/24 – scans my network and return info on machines and service ports listening

~# nmap -sP 192.168.1.100 – attempts to detect if a host is up or down

~# nmap -PN 192.168.1.100 – attempts to detect if a host is up or down (no pings sent)

~# nmap -sT 192.168.1.100 – port scan using TCP

~# nmap -sU 192.168.1.100 – port scan using UDP

~# nmap -O 192.168.1.100 – attempts to identify the remote OS, returns TCP/IP fingerprint

And I could go on, but lets just end these example here and I’m sure you’ll find others.

Run … run, you clever boy … and remember. – Clara Oswald