Test Wifi Internet Issues
Understanding the Operation of Internet Addresses
When using the Internet, it is possible to have a Public IPv4 address such as 153.8.92.10 or an IPv6 address like 2000:d74d:27bb:28e:eb6e:a146:af76:d8e1. This can be verified at https://test-ipv6.com/. However, explaining or using these addresses, as well as calling out MAC addresses like dd:bc:61:ca:dd:fb, can be prone to errors and becomes complex quickly. Moreover, this does not provide any historical data, especially when addressing past issues.
Navigating through Online Sites
In order to access a website such as https://schumm-emard.co, the initial step is to access a DNS server to convert the host portion (schumm-emard) combined with the Top Level Domain (co) of the URL, into an IP address like 195.93.222.152. The computer and browser sends its type with all web requests, for example: Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
Significance of Default Gateways
The default gateway is usually an address configured automatically via DHCP, such as 172.16.159.40 (although they generally end in .1 or .254 depending on the scope size). This is the point where a computer sends all its traffic to be routed onwards. For IPv6, an in-depth discussion is available at how-to-fix-ipv6-connectivity/, with the ability to check on Mac or Linux using the following code:
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 172.16.159.40 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:a8b2:a754:8d80:f9f1%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): {249.53.80.19, 101.239.34.242}
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 dd:bc:61:ca:dd:fb
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 22:5e:8f:7c:31:15
}
Solutions for Resolving Wired and Wireless Connectivity Issues
When it comes to transferring data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Steps to Take on Apple macOS / OSX Devices
Regardless of whether you are running OSX/macOS versions such as 10.15.7, 11.4.5, or 12.2.9, there is a wide range of troubleshooting tools available. However, these tools and scripts do not provide a set of correlated values over time, making automated remote troubleshooting an essential solution, particularly for teams that embrace remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
A very handy tool on OSX/macOS is the sudo wdutil info, which dumps current wireless related settings to the CLI and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a variety of logs, although much of it is only related to wireless at a specific point in time, much like wdutil.
To run it in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. For an interactive run (although there is not much interaction), use the command sudo /usr/bin/sysdiagnose, which will give a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to point Finder to the path. However, be aware of the file sizes, which are approximately 300MB.
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