Amar Helloween

Today we are going to learn how to fix route issues on Linux. Suppose you have 2 NIC interface (one is for public traffic - 100 GBPS Link and other one in Private interface for private communication 10 GBPS Link ). What is the exact issue ? Initially our customers reported that they were unable to reach internet on the box (They tried performing ping 8.8.8.8 -or- ping google.com). It was not working via both IP and domain name even tried with browser. So lets begin the troubleshooting : Step 1 : Replicate the issue from your side, because we need to be 100% sure before deep diving. Step 2 : We were able to replicate the same. It was 100% packet loss. So now we need to check if the public interface is up and running or not . Our public interface is eth1 so run command : ip a This will show you if interface is UP / Down. Eth1 was up and running here. Step 3 : Next I was interested to see how is the traffic going out - is it crossing any single hop or not , whether Gateway is reachable

Here are the list of some useful Linux commands that's used on a day-to-day work and are equally important for interview purposes.  1. How to check memory usage free -h -h is to make the result readable by humans. 2. How to check disk usage df -h 3. How to check CPU Usage top 4. How to quickly find the process id of a program pgrep <ProcessName> 5. How to find the Linux Kernal version uname -r amar@LPF22E8MA:~$ uname -r 4.4.0-19041-Microsoft 6. How to find the Operating System (OS) version cat /etc/os-release lsb_release -a amar@LPF22E8MA:~$ cat /etc/os-release NAME="Ubuntu" VERSION="20.04 LTS (Focal Fossa)" ID=ubuntu ID_LIKE=debian PRETTY_NAME="Ubuntu 20.04 LTS" VERSION_ID="20.04" HOME_URL="https://www.ubuntu.com/" SUPPORT_URL="https://help.ubuntu.com/" BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/" PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy" VERSION_C

Today, we are going to see how to copy a file to remote destination using WINRM. Traditionally SMB Protocol (File Sharing \\Servername\C$) was used to transfer the files but nowadays you will find SMB Protocol disabled on some servers so you will require firewall changes to perform that.  On the other hand WINRM Protocol 5985 is mostly open for Powershell Remote sessions, so we will use that to transfer the files. Lets get started : Step 1 : Create a PS Session for that server  $Session = New-PSSession -ComputerName <ServerName> Step 2 : Use Copy-Item with -ToSession to transfer the file using WINRM Copy-Item -Path C:\Scripts\Amar\TestFile.txt -ToSession $Session -Destination "D:\" TestFile.txt file will get copied from local system to the D Drive of the remote server. Happy Learning :)

Today we are going to learn how to remove an AD User which is not Active since a long time lets say 1 year. As a part of Server hardening best practices, you should always run checks to remove the disabled or orphan accounts from Active directory. We will be using the Active Directory module in Powershell to perform the activity : CODE :  $Date =(Get-Date).AddDays(-365) Get-ADUser -Filter 'LastLogondate -le $Date' -Properties LastLogonDate | Select Name, LastLogonDate To remove the ADUser use : Remove-ADUser -Identity "<SamAccountName>"