Uly.me

cloud engineer

network

Migrate VM to Other Network

Here’s how to move a VM to another network.

Stop the VM.

gcloud compute instances stop server-name \
--zone=us-central1-c \
--project project-id

Migrate the VM. Use self link for network and subnetwork.

gcloud compute instances network-interfaces update server-name \
--zone=us-central1-c \
--network-interface=nic0 \
--network=your-network \
--subnetwork=your-sub-network \
--project project-id

Start the VM.

gcloud compute instances start server-name \
--zone=us-central1-c \
--project project-id

GCP Reserve Alias IP

Make an IP alias reservation.

gcloud compute instances network-interfaces update instance-name \
--zone us-central1-c \
--aliases default:/32 \
--project project-id

GCP Add New Route

Here’s how to add a new route in Google Cloud Platform.

gcloud compute routes create name-of-new-route \
  --destination-range=200.20.0.0/15 \
  --next-hop-gateway=default-internet-gateway \
  --project=host-project \
  --network="default" \
  --priority=900

AWS Enable Enhance Network Support

When changing machine types, you may be asked to enable the latest ENA driver for Enhanced Network Support on an Amazon EC2 instance. There are several instructions depending on the Linux OS flavor. Here are the instructions to enable. In some cases, you may need to rebuild the kernel module. To verify that the ena module is installed, use the modinfo command as shown in the following example.

modinfo ena

You also may have to enable the enhanced networking attribute on the instance.

aws ec2 modify-instance-attribute --instance-id instance_id --ena-support

Nmap

Here’s how to list all the devices on your network using nmap.

nmap -sn 192.168.0.0/24

If nmap is not installed, install it.

yum install nmap
apt install nmap

Netstat

Netstat is a utility for gathering network statistics. It comes preinstalled on most systems.

If missing, here’s how to install.

# Redhat, CentOS
yum install net-tools
# Debian, Ubuntu, Mint
apt install net-tools
# SLES, SUSE
zypper install net-tools

Here are some common and useful commands.

# show version
netstat -v
# show routing table
netstat -nr
# show network interface statistics
netstat -ai
# show network connections
netstat -ant
# show network services
netstat -tulpn

GCP ILB Issue Targets Not Healthy

I ran into an issue with Google Compute Engine TCP internal load balancer. The targets are unhealthy although all configs were correct installed. At one time the targets were working, but somehow they became unhealthy. In the end, 3 things needed to be checked.

  1. Make sure GCP’s guest environment is installed.
  2. Add the internal load balancer VIP address to the network properties.
  3. Add route via cmd. “route ADD VIP MASK 255.255.255.255”

You will need to change the server’s IP from DHCP to static to add ILB VIP.