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Windows Networking Troubleshooting.md

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Windows Networking Troubleshooting Guide

Questions to answer:

  • Is an IP address assigned?
  • What is the subnet mask?
  • What is the default gateway?
  • What is the DNS server set as?
  • Which interface are you using to communicate?
  • What port are you trying to reach?
  • What protocol are you trying to talk over?
  • Is the interface enabled?
  • Is the firewall blocking your traffic?
  • Do you need to be connected to a VPN?

Windows Networking Commands:

arp - Displays and modifies the IP-to-Physical address translation tables used by address resolution protocol (ARP).

ipconfig - IP interface configuration details

getmac - Display the MAC address for network adapters on a system.

netstat - Displays protocol statistics and current TCP/IP network connections.

nslookup - Queries the specified DNS server and retrieves the records for the domain.

ping - Whatever you want it to be.

route - Manipulates network routing tables.

tracert - Trace the path that a packet.

After each step, check if you're networking issue is fixed.

Step 1:

  • Check Layer 1 (cables are pugged in and devices are powered on)

Step 2:

  • Check if the firewall is enabled and which profile is active (Domain, Public, Private)
    • netsh advfirewall show currentprofile
  • Check your firewall rules
    • Open Windows Firewall with Advanced security, make note of the default behavior for traffic that does not match a rule. Check both inbound and outbound rules for anything that may be blocking your traffic. Filter by profile and filter by state .

Step 3:

  • Check the interface config
    • ipconfig /all - find the relevant interface
    • To get to the adapter settings:
      • Right-click the network icon in the system tray
      • Right-click the relevant adapter > Properties
      • Scroll down to IPv4 > Properties (Disable IPv6 while you're here)
      • OR Control Panel > Network & Internet > Network & Sharing Center > Click connection name > Properties
    • If a DHCP address is not desired or isn't being assigned, unselect "Obtain an IP address Automatically"
    • Set a static IP address in the proper subnet, set the correct subnet mask, set the default gateway IP (confirm with Network Admin)
    • Set primary and seconday DNS servers (confirm with Network Admin)
    • It's usually best to check "Validate Settings Upon Exit"

Step 4:

  • Check what your default routes are
    • netstat -r
    • route print
    • If necessary, flush the routing table after statically setting your IP settings then try to send the traffic you want (route -f)
  • Check DNS records
    • ipconfig /displaydns

Step 5:

  • Make sure that the networking related services are running

Step 6:

  • Confirm MAC addresses in your ARP table are correct (may require interacting with other humans)

Step 7:

  • Start a packet captue to see if you can gain any more insight into the issue.
    • Wireshark
    • Windows Message Analyzer
      • (In Administrative Command Prompt)
      • netsh trace start capture=yes
      • netsh trace stop
      • Attach both files to the case
      • You can then save and export the capture to view in Wireshark

If all of the above fails, THEN it's ok to yell at the network admin :)