Karan Kaw's Blog

Thursday, June 17, 2021

EBS --------> 1 EC2 Instance is mapped to EBS - Block Level Storage

EFS ----------> Multiple EC2 Instances - Mounted to this File System - Common across multiple Apps

The main differences between EBS and EFS is that EBS is only accessible from a single EC2 instance in your particular AWS region, while EFS allows you to mount the file system across multiple regions and instances.

S3 --> S3 is Object Level storage. S3 is not limited to EC2, Its linked to CloudFront through which many Media etc are hosted there.

Monday, June 14, 2021

IPTABLES, Firewall, Actual Firewall + Security Group - AWS

https://www.tecmint.com/fix-no-route-to-host-ssh-error-in-linux/

https://www.cyberciti.biz/faq/how-to-list-all-iptables-rules-in-linux/

sudo nmap -p 6900,25,22,8080,21000,7856,9084 10.79.197.70

sudo iptables -S

sudo nmap -p 6900,25,22,8080,21000,7856,9084 10.79.197.70

https://www.e2enetworks.com/help/knowledge-base/how-to-open-ports-on-iptables-in-a-linux-server/#step-1-list-the-current-iptables-rules

sudo iptables -D IN_public_allow -p tcp -m tcp --dport 7856 -m conntrack --ctstate NEW,UNTRACKED -j ACCEPT

sudo iptables -A IN_public_allow -p tcp -m tcp --dport 7856 -m conntrack --ctstate NEW,UNTRACKED -j ACCEPT

Sunday, June 13, 2021

Zscaler Private Access (ZPA) , CHATTR Linux, Immuable, VPC -> PrefixList

https://superuser.com/questions/1647896/putty-key-format-too-new-when-using-ppk-file-for-putty-ssh-key-authentication

VPC -> PrefixList
https://docs.aws.amazon.com/vpc/latest/userguide/managed-prefix-lists.html

https://aws.amazon.com/marketplace/pp/prodview-epy3md7fcvk4g?ref=cns_srchrow

https://www.fugue.co/blog/cloud-network-security-101-aws-security-groups-vs-nacls

https://www.javatpoint.com/aws-nacl-vs-security-group

https://mylearningsonline.com/aws-services/aws-vpc-security-group-nacl/

https://www.davidc.net/sites/default/subnets/subnets.html

http://www.cronmaker.com/

https://www.baeldung.com/linux/grep-sed-awk-differences#1-basic-syntax-1

chattr +i [To make it immutable, Its not related to access permissions] - Change Attribute

SetUserBit

SetGroupBit chmod 2775 chmod +ug rw

which Which executable

whereis

https://stackoverflow.com/questions/39239276/how-to-enable-a-directory-listing-in-apache-web-server

Saturday, June 5, 2021

Azure Pipelines, YAML Schema

https://docs.microsoft.com/en-us/azure/devops/pipelines/yaml-schema?view=azure-devops&tabs=schema%2Cparameter-schema

https://docs.microsoft.com/en-us/azure/devops/pipelines/get-started/key-pipelines-concepts?view=azure-devops

https://docs.microsoft.com/en-us/azure/devops/pipelines/repos/azure-repos-git?view=azure-devops&tabs=yaml#ci-triggers

https://faun.pub/reduce-your-build-time-using-caching-in-azure-pipelines-7a7bd0201cee

Resources

Trigger

Pipeline -> Stage(Implicit) -> Jobs -> Steps [Task, Script, Checkout]

jobs:

- job: Job_1

displayName: Agent job 1

pool:

vmImage: ubuntu-latest

steps:

-script: echo "Hello World"

pool:

name: Default

demands: SpecialSoftware # Check if SpecialSoftware capability exists

stages:

- stage: A

jobs:

- job: A1

- job: A2

- stage: B

jobs:

- job: B1

- job: B2

https://docs.microsoft.com/en-us/azure/devops/pipelines/process/phases?view=azure-devops&tabs=yaml

stages:

- stage: A

# stage B runs if A fails

- stage: B

condition: failed()

# stage C runs if B succeeds

- stage: C

dependsOn:

- A

- B

condition: succeeded('B')

If you choose to specify a pool at the stage level, then all jobs defined in that stage will use that pool unless otherwise specified at the job-level.

stages:

- stage: A

pool: StageAPool

jobs:

- job: A1 # will run on "StageAPool" pool based on the pool defined on the stage

- job: A2 # will run on "JobPool" pool

pool: JobPool

jobs:

- job: Foo

steps:

- script: echo Hello!

condition: always() # this step will always run, even if the pipeline is canceled

- job: Bar

dependsOn: Foo

condition: failed() # this job will only run if Foo fails

https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/hosted?view=azure-devops&tabs=yaml

jobs:

- job: Debug

steps:

- script: echo hello from the Debug build

- job: Release

dependsOn: Debug

steps:

- script: echo hello from the Release build

You can organize pipeline jobs into stages. Stages are the major divisions in a pipeline: "build this app", "run these tests", and "deploy to pre-production" are good examples of stages. They are logical boundaries in your pipeline where you can pause the pipeline and perform various checks.

Pipeline > Stages >Stage>Steps>Step

jobs:

- job: A

steps:

- bash: echo "A"

- job: B

steps:

- bash: echo "B"

If you organize your pipeline into multiple stages, you use the stages keyword.

If you choose to specify a pool at the stage level, then all jobs defined in that stage will use that pool unless otherwise specified at the job-level

stages:

- stage: A

jobs:

- job: A1

- job: A2

- stage: B

jobs:

- job: B1

- job: B2

When you define multiple stages in a pipeline, by default, they run sequentially in the order in which you define them in the YAML file. The exception to this is when you add dependencies. With dependencies, stages run in the order of the dependsOn requirements

stages:

- stage: string

dependsOn: string

condition: string

-----------------------------------------------------------

You can organize your pipeline into jobs. Every pipeline has at least one job. A job is a series of steps that run sequentially as a unit. In other words, a job is the smallest unit of work that can be scheduled to run.

In the simplest case, a pipeline has a single job. In that case, you do not have to explicitly use the job keyword

jobs:

- job: myJob

timeoutInMinutes: 10

pool:

vmImage: 'ubuntu-16.04'

steps:

- bash: echo "Hello world"

/usr/lib/jvm/adoptopenjdk-11-hotspot-amd64

# update-alternatives --config java

update-alternatives --list java

echo ls /etc/alternatives