Moving a Website to Another Server – Redirect Traffic to the New Server While DNS Propagates (for No Downtime)

If you're migrating a website from one server to another and have updated the DNS for the domain to point to the new server, some traffic will still be directed to the old server due to DNS caching.  So, while the DNS changes propagate over the internet (can take up to three days), you can still redirect traffic to the new server from the old server so that you won't suffer any downtime. 

On the old server, run these commands to redirect web traffic on port 80 (http) and port 443 (https) to the new server (adjust the {DESTINATION_IP_ADDRESS} variable accordingly):

echo 1 >/proc/sys/net/ipv4/ip_forward
iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination {DESTINATION_IP_ADDRESS}:80
iptables -t nat -A PREROUTING -p tcp --dport 443 -j DNAT --to-destination {DESTINATION_IP_ADDRESS}:443
iptables -t nat -A POSTROUTING -p tcp -d {DESTINATION_IP_ADDRESS} --dport 80 -j MASQUERADE
iptables -t nat -A POSTROUTING -p tcp -d {DESTINATION_IP_ADDRESS} --dport 443 -j MASQUERADE

Reference:  https://serverfault.com/questions/371833/changing-servers-redirect-to-new-ip-no-downtime#371870

Dual Boot Linux (Ubuntu 22.04) and Windows 11 on Modern Systems – UEFI

In order to setup a dual boot of Windows 11 and Ubuntu 22.04 on a modern system that uses UEFI, follow these steps.

1. Install Windows 11 first leaving some unpartitioned space (at least 60GB is my recommendation) on the drive you're installing Windows on.
2. Boot up the Ubuntu installer.
3. During installation, you'll be presented with an Installation Type options screen.  Choose "Something else". 

4. On the next screen, you'll see a list of drives and partitions.  On the same drive you installed Windows, create 3 new partitions. 
   1. Create an EXT4 partition for the / mount point at least 40GB in size (this is the main drive for Linux files).
   2. Create a SWAP partition at least 18GB in size.
   3. Create an EFI partition at least 500MB in size.  This is extremely important in order to get grub to install properly. 
5. Leave the "Device for boot loader installation" set as the top level drive that Windows and Ubuntu was / is being installed on.  You should not select an individual partition here.

6. Complete the installation process. 
7. You might need to change the UEFI boot order in the BIOS of your system to boot Ubuntu / Linux first versus booting the Windows EFI partition.  Since you created an EFI partition for your Linux install, it should show up as a bootable option in the bios.  Set / adjust accordingly.
8. That's it!

Creating SSL PFX Certificate for IIS Windows

To create a PFX certificate file you can import into IIS on Windows from an openssl private key and certificate file on Linux, use the below command:

openssl pkcs12 -export -legacy -out iis_certificate.pfx -inkey your_private_key.key -in your_cert.crt -certfile your_chain.crt