Network

SSH (Secure Shell)¶

• Login to a remote server:

  ssh username@remote_host
  

• Connect to a remote server on a specific port:

  ssh -p port_number username@remote_host
  

• Run a command on a remote server:

  ssh username@remote_host command_to_run
  

• Use an SSH key for authentication:

  ssh -i /path/to/private_key username@remote_host
  

• SSH Tunneling (Local Port Forwarding):

  ssh -L local_port:destination_host:destination_port username@remote_host
  

• SSH Reverse Port Forwarding:

  ssh -R remote_port:destination_host:destination_port username@remote_host
  

• Copy SSH public key to server (Password-less SSH):

  ssh-copy-id username@remote_host
  

SCP (Secure Copy Protocol)¶

• Copy file from local to remote:

  scp /path/to/local_file username@remote_host:/path/to/remote_dir
  

• Copy file from remote to local:

  scp username@remote_host:/path/to/remote_file /path/to/local_dir
  

• Copy directory recursively:

  scp -r /path/to/local_dir username@remote_host:/path/to/remote_dir
  

File Transfer with Rsync¶

• Sync files from local to remote:

  rsync -avz /path/to/local_dir username@remote_host:/path/to/remote_dir
  

• Sync files from remote to local:

  rsync -avz username@remote_host:/path/to/remote_dir /path/to/local_dir
  

• Delete files from the destination that don’t exist on the source:

  rsync -avz --delete /path/to/source_dir username@remote_host:/path/to/destination_dir
  

Network Tools¶

• Check network connectivity (Ping):

  ping remote_host
  

• Trace route to a host:

  traceroute remote_host
  

• Display network interfaces and IP addresses: or

  ip addr
  

  ifconfig
  

• Check open ports on a remote host:

  nmap remote_host
  

• Check currently established connections: or

  netstat -an
  

  ss -tuln
  

File and Process Operations¶

• View open files used by a process:

  lsof -p process_id
  

• Kill a process by its name:

  pkill process_name
  

• Kill a process by its PID:

  kill -9 process_id
  

Networking & Monitoring¶

• Monitor traffic on an interface:

  tcpdump -i interface
  

• Check bandwidth usage:

  iftop -i interface
  

• Query DNS for a domain:

  nslookup domain_name
  

• Perform a more detailed DNS query:

  dig domain_name
  

Firewall Configuration (ufw)¶

• Enable UFW (Uncomplicated Firewall):

  sudo ufw enable
  

• Allow a specific port:

  sudo ufw allow port_number
  

• Check UFW status:

  sudo ufw status
  

Network Configuration¶

• Change hostname:

  sudo hostnamectl set-hostname new_hostname
  

• View routing table:

  ip route
  

• Add a static route:

  ip route add destination_network via gateway_ip dev interface
  

Other Useful Commands¶

• Speedtest CLI (Check internet speed):

  speedtest-cli
  

• Download file from the web: or

  wget file_url
  

  curl -O file_url
  

• Test the reachability of a specific port:

  nc -zv remote_host port_number