Test Common Wifi Internet Issues
Understanding Internet Addressing Process
When connecting to the Internet, you are assigned a unique address such as the Public IPv4 address 173.129.7.66 or an IPv6 address like 2000:54f9:864:8526:1a39:7dcc:16f6:99cd. These addresses can be verified at https://test-ipv6.com/. However, conveying these addresses to individuals less knowledgeable about technology, or even identifying MAC addresses like 8d:6a:db:cc:ca:f4, can be prone to errors and quickly become complex. Moreover, these addresses do not provide historical data, especially from previous incidents.
Navigating the World Wide Web
When accessing a webpage such as https://gusikowski.com, the first step is to request information from a DNS server. This server translates the host portion (gusikowski) and the Top Level Domain (com) of the URL into an IP address, such as 69.1.189.219. Additionally, your computer and browser relay their type with all web requests, for example:
Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
Significance of Default Gateways
Typically, a default gateway is automatically assigned via DHCP. Your computer is allocated a default gateway, such as 10.38.249.155 (commonly ending in .1 or .254 based on the scope size), to which all its traffic is directed for further routing. For IPv6, a more detailed explanation is available in the article how-to-fix-ipv6-connectivity/, and the process can be verified on Mac or Linux operating systems using:
<br>
IPv4 Routes and the Host IPv4 Route Table (inc. VPN)
netstat -rn -f inet | egrep -i "default|0/1|128.0/1"
0/1 172.18.12.193 UGScg utun3 default 10.38.249.155 UGScg en0 128.0/1 172.18.12.193 UGSc utun3
Note: We are not just looking for the default but also for any VPN that overrides the public v4 address space.
IPv6 Routes and the Host IPv6 Route Table (inc. VPN)
netstat -rn -f inet6 | egrep -i "default|2000::/3"
If you have IPv6 active the above should return at least one route (as per below) via a known interface such as “en0 " on a Mac.
default fe80:1247:ac25:a685:30b6%en0 UGcg en0 default fe80::%utun0 UGcIg utun0 default fe80::%utun1 UGcIg utun1 default fe80::%utun2 UGcIg utun2 2000::/3 utun3 USc utun3
Note: We are not just looking for the default but also for any VPN that overrides the public v6 address space.
Debugging DHCP for both IPv4 and IPv6
To get a look at the low level DHCP configuration (Mac/Linux):
ipconfig getpacket en0
...
domain_name_server (ip_mult): {1.77.74.45, 200.143.202.144}
end (none):
...
So, in the above we are not getting IPv6 DNS servers from the DHCPv4 reply but…
ipconfig getv6packet en0
DHCPv6 REPLY (7) Transaction ID 0x80940b Length 76
Options[4] = {
CLIENTID (1) Length 14: DUID LLT HW 1 Time 668691856 Addr 8d:6a:db:cc:ca:f4
DNS_SERVERS (23) Length 32: 2606:4700:4700::1111, 2001:4860:4860::8844
DOMAIN_LIST (24) Length 0: Invalid
SERVERID (2) Length 10: DUID LL HW 1 Addr ab:3f:a5:91:6a:78
}
Diagnose and Resolve Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you might be using a wired or wireless (Wi-Fi) medium at the physical and data layer.
Tips for Apple macOS / OSX Users
Whether you’re running 10.15.6, 11.2.3, or 12.3.1, there are various troubleshooting tools available for OSX/macOS. However, these tools don’t provide a consistent set of related values over time. This is where automated remote troubleshooting becomes essential, particularly for teams engaged in remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
One valuable tool on OSX/macOS is the sudo wdutil info command, which provides current wireless settings and can be configured to generate specific troubleshooting logs. Additionally, the sysdiagnose tool offers a comprehensive range of logs, although much of it is only relevant in relation to wireless, similar to wdutil.
To run sysdiagnose in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, use sudo /usr/bin/sysdiagnose and be prepared for large file sizes of about 300MB. After running the command, you can locate the logs in Finder at the correct location or navigate to /var/tmp using Cmd+Shift+G.
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