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How to generate an RSA Keypair

Generate a certificate (PEM)

For more security use -aes512 4096

openssl genrsa -out key.pem -aes256 2048

Extract public key as PEM

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Various certificate-conversions

Exports

Export public certificate/key from pfx

openssl pkcs12 -in <cert>.pfx -clcerts -nokeys -out <pub_cert>.pem

Export certificate

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#!/bin/bash
# more shortcuts at https://www.sslshopper.com/article-most-common-java-keytool-keystore-commands.html

# list certificates included in a keystore
keytool -list -v -keystore keystore.jks
# with specific storetype:
keytool -list -v -storetype jceks keystore.jks

# check a specific certificate
keytool -printcert -v -file mydomain.crt

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# check active connections
netstat -ant | grep 4444 | wc -l

# only established connections
netstat -ant | grep 4444 | grep -i established | wc -l
# idle connections
netstat -an -f inet | grep -v EST | grep IDLE | wc -l


# in loop

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# first, format USB as ExtFAT (using Disk Utility)

# convert .iso to .img
hdiutil convert -format UDRW -o ./ubuntu-18.04.2-server-amd64.img ubuntu-18.04.2-server-amd64.iso

# mac adds .dmg at the end, we need to remove that
mv ubuntu-18.04.2-server-amd64.img.dmg ubuntu-18.04.2-server-amd64.img

# find out the disk-name:
diskutil list

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Various Links for developers

Linux

• Debian Manpages
• DigitalOcean openssl essentials

Development

• HTTP CSP-Headers

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# How to do updates to your environment
# more details to deployments and scaling:
# https://kubernetes.io/docs/concepts/workloads/controllers/deployment/

# 1. update the deployment.yml file and run
kubectl apply -f <deployment.yml>

# 2. update an image:
kubectl set image <deployment/nginx-deployment> <nginx>=<nginx:1.9.1>

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# Secrets handling
# create secret
kubectl create secret generic db-user-pass --from-file=./username.txt --from-file=./password.txt

# get Secrets
kubectl get secrets
# get secret details
kubectl get secret mysecret -o yaml
# encode secret values
echo "asdfghjkl==" | base64 --decode

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# scale to 10 replicas
kubectl scale deployment <nginx-deployment> --replicas=10

# auto-Scaling
kubectl autoscale deployment <nginx-deployment> --min=2 --max=8 --cpu-percent=80

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# Documentation: https://kubernetes.io/docs
#
# get kubernetes version and info
kubectl version

# get infor on pods
kubectl get pods
# get info on deployments
kubectl get deployments
kubectl describe deployments