Diagnosing Network Connections - Paiet/Tech-Journal-for-Everything GitHub Wiki

  • ping - Test server connectivity
  • dig - Perform a DNS lookup
  • nslookup - Perform a DNS lookup
  • host - Perform a DNS lookup
  • traceroute - Display the path to a host
  • tracepath - Test connectivity along the path
  • telnet - Unencrypted shell session
  • ssh - Encrypted shell session
  • ftp - Unencrypted file transfers
  • ifconfig - Display information about network interfaces
  • route - Display and manipulate the routing table
    • route -n displays routing table
    • Useful for temporary changes
    • route add default gw 192.168.0.1
    • route add -net 192.168.1.0 netmask 255.255.255.0 gw 192.168.0.1
  • netstat - Display network connections
    • netstat -atp (All sessions)
    • netstat -tp (Active sessions)
    • netstat --route displays routing table
    • netstat --program attempts to display software using ports
  • Reset Networking
    • service network restart
    • systemctl restart network.service
      • ifup eth0 - Enable an interface
    • ifdown eth0 - Disable an interface
  • Packet Capture
    • tcpdump
    • Displays packets passing through an interface
    • tcpdump -i eth0 > data.txt
    • tail -f ./data.txt