firewall

Terraform GCP Firewall

by Ulysses · Jun 6, 2021

How to create GCP firewall via Terraform.

Ingress

provider "google" {
    project = "project-id"
}
resource "google_compute_firewall" "default" {
    name    = "test-firewall"
    description = "this is a test firewall"
    priority = "1000"
    direction = "INGRESS"
    network = "projects/project-id/regions/us-east1/subnetworks/default"
    target_service_accounts = ["service-account-compute@developer.gserviceaccount.com"]
    source_ranges = ["10.128.0.0/20"]
    allow {
        protocol = "tcp"
        ports    = ["80", "8080", "1000-2000"]
    }
}

Egress

provider "google" {
    project = "project-id"
}
resource "google_compute_firewall" "default" {
    name    = "test-firewall"
    description = "this is a test firewall"
    priority = "1000"
    direction = "EGRESS"
    network = "projects/project-id/regions/us-east1/subnetworks/default"
    target_service_accounts = ["service-account-compute@developer.gserviceaccount.com"]
    destination_ranges = ["10.128.0.0/20"]
    allow {
        protocol = "tcp"
        ports    = ["80", "8080", "1000-2000"]
    }
}

Service account to Service account.

provider "google" {
    project = "project-id"
}
resource "google_compute_firewall" "default" {
    name    = "test-firewall"
    description = "this is a test firewall"
    priority = "1000"
    direction = "INGRESS"
    network = "projects/project-id/regions/us-east1/subnetworks/default"
    source_service_accounts = ["source-service-account-compute@developer.gserviceaccount.com"]
    target_service_accounts = ["target-service-account-compute@developer.gserviceaccount.com"]
    source_ranges = ["10.128.0.0/20"]
    allow {
        protocol = "tcp"
        ports    = ["80", "8080", "1000-2000"]
    }
}

GCP Firewall Source Service Account

by Ulysses · Feb 16, 2021

Here’s how to create a firewall from service account to service account.

gcloud compute firewall-rules create "firewall-name" \
--description="firewall-description" \
--priority "1000" \
--direction INGRESS \
--action allow \
--network "network-name" \
--source-service-accounts="service@account.net" \
--target-service-accounts="service@account.net" \
--rules tcp:9001

Instead of source-range, it’s using source-service-accounts.

AWS EC2 Firewall rules are defined within security groups. Security groups are attached to an instance. An instance can have up to 5 security groups. Essentially, this script gathers all the security groups associated with an instance, loops through them, and then outputs the ingress and egress rules of each security group to a file in a text format.

#!/bin/bash
# set variables
instanceid='i-xxxxxxxxxxxxxxxx'
region='us-east-1'
profile='sample'
# log and temp files
output="ec2-sg.log"
tmpfil="ec2-sg.tmp"
# empty log at start
> $output
# get sg ids
aws ec2 describe-instances \
--instance-ids $instanceid \
--region $region \
--profile $profile \
--query 'Reservations[*].Instances[*].SecurityGroups[*].[GroupId]' --output text > $tmpfil
while read -r id; do
  echo '============================================' >> $output
  echo $id >> $output
  echo '============================================' >> $output
  echo '---------------- INGRESS -------------------' >> $output
  aws ec2 describe-security-groups \
  --group-ids $id \
  --profile $profile \
  --region $region \
  --output text \
  --query 'SecurityGroups[].IpPermissions[].[FromPort,ToPort,IpProtocol,IpRanges[].CidrIp[]|[0]]' >> $output
  echo '---------------- EGRESS --------------------' >> $output
  aws ec2 describe-security-groups \
  --group-ids $id \
  --profile $profile \
  --region $region \
  --output text \
  --query 'SecurityGroups[].IpPermissionsEgress[].[FromPort,ToPort,IpProtocol,IpRanges[].CidrIp[]|[0]]' >> $output
done < $tmpfil

Here’s a sample output.

============================================
sg-xxxxxxxxxxxxxxx
============================================
---------------- INGRESS -------------------
5985    5985    tcp     10.0.0.220/32
10005   10005   tcp     10.0.0.164/32
---------------- EGRESS --------------------
80      80      tcp     10.0.0.14/32
40000   65535   udp     10.0.0.0/8
3389    3389    tcp     10.0.0.96/32
9389    9389    tcp     10.0.0.0/8
5985    5986    tcp     10.0.0.96/32

GCP Create Firewall with Tags

by Ulysses · May 28, 2020

Here’s another way to create a firewall in GCP using network tag as targets.

gcloud compute firewall-rules create "firewall-name" \
    --description="egress rule to allow port 8000 to destination" \
    --priority "1000" \
    --direction EGRESS \
    --action allow \
    --network "your-network" \
    --target-tags="your-network-tag" \
    --destination-ranges="10.0.0.1/32" \
    --rules tcp:8000

GCP SDK Firewall Rule AH and ESP

by Ulysses · Feb 26, 2020

Here’s how to add a GCP firewall rule with the AH (authentication header) and ESP (Encapsulating Security Payload) protocols.

gcloud compute firewall-rules update "firewall-name" \
    --description="firewall description" \
    --priority "1000" \
    --target-service-accounts="service-account@gserviceaccount.com" \
    --destination-ranges="10.0.0.0/8" \
    --rules 50,51,tcp:80,udp:1000

There is no need to add protocols for AH and ESP. Just the port numbers.