Useful Commands

commands.md

Network

# TCP Ping
timeout 2 bash -c -- "while true;do nc -z example.com 443 -v -w 3;done"

Processes

 # Kill a process listening on a port
 lsof -ti:5901 | xargs kill -9

Certificates

Overview: https://sites.google.com/site/ddmwsst/digital-certificates

Generating self-signed certificates

# Use a DNS name in subject alt name
serverName=example.com
openssl req \
  -x509 \
  -sha256 \
  -nodes \
  -newkey rsa:2048 \
  -days 365 \
  -subj "/CN=$serverName/O=example inc/C=IN/ST=Haryana/L=Gurgaon" \
  -addext "subjectAltName=DNS:$serverName" \
  -keyout example.key \
  -out example.crt

# Use an IP address in subject alt name
serverIp=10.0.0.1
openssl req \
  -x509 \
  -sha256 \
  -nodes \
  -newkey rsa:2048 \
  -days 365 \
  -subj "/CN=$serverIp/O=example inc/C=IN/ST=Haryana/L=Gurgaon" \
  -addext "subjectAltName=IP:$serverIp" \
  -keyout example.key \
  -out example.crt

Checking certificates

# Check a key
openssl rsa -in example.key -check

# Check a certificate
openssl x509 -in example.crt -text -noout

# Check server TLS certificates
openssl s_client -connect example.com:443

# Obtain TLS certificate thumbprint
openssl s_client -connect example.com:443 < /dev/null 2>/dev/null | openssl x509 -fingerprint -noout -in /dev/stdin

# Check expiry
openssl s_client -servername example.com -connect example.com:443 2>/dev/null | openssl x509 -noout -date

String Manipulation

# Certificate as a single string (no line breaks)
awk 'NF {sub(/\r/, ""); printf "%s\\n",$0;}'  c.pem

Remove password from a pkcs12

# PASSWORD is your current password
# YourPKCSFile is the file you want to convert
# NewPKCSWithoutPassphraseFile is the target file for the PKCS12 without passphrase

# First, extract the certificate:
openssl pkcs12 -clcerts -nokeys -in "YourPKCSFile" -out certificate.crt -password pass:PASSWORD -passin pass:PASSWORD

# Second, the CA key:
openssl pkcs12 -cacerts -nokeys -in "YourPKCSFile" -out ca-cert.ca -password pass:PASSWORD -passin pass:PASSWORD

# Third, the private key:
openssl pkcs12 -nocerts -in "YourPKCSFile" -out private.key -password pass:PASSWORD -passin pass:PASSWORD -passout pass:TemporaryPassword

# Now remove the passphrase:
openssl rsa -in private.key -out "NewKeyFile.key" -passin pass:TemporaryPassword

# Put things together for the new PKCS file:
cat "NewKeyFile.key" "certificate.crt" "ca-cert.ca" > PEM.pem
openssl pkcs12 -export -nodes -CAfile ca-cert.ca -in PEM.pem -out "NewPKCSWithoutPassphraseFile"

github.com/distribution/distribution

Monolithic Upload blob

# Initiate upload
curl -H "Authorization: Basic <base64-username-password>" -X POST --data "" https://localhost/v2/repo/blobs/uploads/

# Complete upload
curl -H "Content-Type : application/octet-stream" -H "Authorization: Basic <base64-username-password>" -X PUT --data "{}" --insecure  "https://<opaque-path-from-previous-step>&digest=sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a"