Linux Bash Snippets

snippets.sh

# Start reverse SSH tunnel from internal server to external endpoint on port 443
# Port 8081 on external endpoint will then be connectable to internal server localsql port 1433
ssh -N -R 0.0.0.0:8081:localsql:1433 remoteuser@company-endpoint.westeurope.cloudapp.azure.com -p 443 -i ./remoteuser.pem

# Show certificate for SMTP server with implicit TLS
openssl s_client -connect smtp.some-server.com:465 -servername smtp.some-server.com

# Show certificate for SMTP server with explicit TLS
openssl s_client -connect smtp.some-server.com:587 -servername smtp.some-server.com -starttls smtp

# Fetch date from an API where URL is stored in sqlite database and set locally as a replacement for NTP
sqlite3 /opt/owi/SqlOWI.db "select Value from AppSettings where Key='ApiUrl'" | xargs -i curl -s {}/_api/check | grep -oP \(\?\<=\time\":\"\)[^\"]+ | xargs -i date --set={}