Complete Reference with Copy-Paste Examples
Part of The Direct Path to Linux Ubuntu
— free for all students and developers.
Every web request, API call, and webhook uses HTTP. Understanding methods, status codes, and headers is the foundation of all web development.
Browsers block unencrypted HTTP. Let's Encrypt provides free certificates. OpenSSL is the universal toolkit for all certificate operations.
Every Linux server is accessed via SSH. Key authentication, tunnels, and rsync are daily tools for every developer and sysadmin.
OAuth2, JWT, and MFA protect applications. OWASP Top 10, bcrypt, CSP headers, and fail2ban prevent the most common attacks.
Run Protocols:
# HTTP tools
curl https://api.example.com/users # GET request
curl -X POST -H "Content-Type: application/json" -d '{}' url # POST
wget -O file.html https://example.com/ # download file
# TLS / Certificates
openssl genrsa -out server.key 4096 # generate key
openssl x509 -in cert.pem -text -noout # inspect cert
openssl s_client -connect example.com:443 # test TLS
sudo certbot --apache -d example.com # Let's Encrypt
# SSH
ssh-keygen -t ed25519 -C "email@example.com" # generate key
ssh-copy-id user@host # copy key to server
ssh user@host # connect
scp file.txt user@host:/path/ # copy file
rsync -avz ./local/ user@host:/remote/ # sync
# Python
pip install requests pyjwt bcrypt paramiko
