Troubleshooting Application Networking - Paiet/Tech-Journal-for-Everything GitHub Wiki

  • Testing client connectivity
    • telnet - Unencrypted shell session
    • ssh - Encrypted shell session
    • ftp - Unencrypted file transfers
  • Testing non-standard services
    • netcat
      • Tests connections to hosts
      • nc
      • sudo apt install netcat
      • nc itpro.tv 80
      • GET
      • Ctrl-D
      • netstat -an or ss -an
  • Packet Capture
    • tcpdump
    • Displays packets passing through an interface
    • tcpdump -i eth0 > data.txt
    • tail -f ./data.txt
  • Reset Networking
    • sudo service network restart
    • sudo systemctl restart network.service
    • sudo /etc/init.d/networking restart
    • sudo systemctl restart systemd-resolved
      • sudo ifup eth0 - Enable an interface
    • sudo ifdown eth0 - Disable an interface