How Do You Check Wifi Connectivity

Understanding the Functioning of Internet Addressing

When using the Internet, individuals can obtain a Public IPv4 address, such as 142.158.205.201, or an IPv6 address like 2000:9372:7d2f:34ef:1115:e6b0:5807:eed0. Verification of this can be done at https://test-ipv6.com/. However, attempting to communicate these addresses, or even referencing MAC addresses like e9:fe:76:34:21:c3, can be prone to errors and quickly become complex for those not well-versed in technology. Furthermore, this method does not provide any historical data, especially from previous occurrences of problems.

Navigating the Internet

When wanting to access a web page, such as https://ratke-robel.info, the first step is to contact a DNS server to convert the host portion (ratke-robel) along with the Top Level Domain (info) of the URL to an IP address, such as 224.213.240.139. With each web request, your computer and browser actually conveys its type, as seen in an example like
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A.

Significance of Default Gateways

Typically, the default gateway is an address that is automatically configured via DHCP. A default gateway could be 192.168.193.83 (although they usually end in .1 or .254 depending on the scope size), and it is where a computer sends all its traffic to be routed onwards. For a detailed explanation on IPv6, refer to how-to-fix-ipv6-connectivity/. Verification on Mac or Linux systems can be done using:

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  192.168.193.83    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:af1a:1150:c754:8c0c%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): {252.136.82.48, 140.235.106.139}
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 e9:fe:76:34:21:c3
  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 eb:ab:4d:58:72:31
}

Resolve Connectivity Issues for Wired and Wireless Networks

When it comes to transmitting data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.

Troubleshooting on Apple macOS / OSX

Regardless of the version of OSX/macOS you are using, whether it’s 10.11.7, 11.0.8, or 12.3.6, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes especially valuable, particularly for teams that have embraced remote work and Work From Anywhere (WFA) practices.

Utilizing Built-in Scripts for Assistance

A very useful tool on OSX/macOS is ‘sudo wdutil info’, which provides a dump to the CLI of current wireless settings, and can also be configured to generate specific troubleshooting logs. Additionally, the ‘sysdiagnose’ tool can be used to generate a wide range of logs, although much of it is only point-in-time information related to wireless, similar to wdutil. To run ‘sysdiagnose’ in the background, use the command ‘sudo nohup /usr/bin/sysdiagnose -u &’ and it will write logs to ‘/var/tmp/.tar.gz’. If you prefer to run it interactively, use ‘sudo /usr/bin/sysdiagnose’ and it 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’ using Finder with Cmd+Shift+G. Just be mindful of the file sizes, which are approximately 300MB.

Possibly Helpful Videos

Video	Title	Channel
	Wireless Adjuster Certification - Do You Need It?	Wireless LAN Professionals
	Hotspot 2.0 WLPC Wireless LAN Weekly EP 49	Wireless LAN Professionals
	Real World Protocol Analysis Peter Mackenzie WLPC_EU Lisbon 2017	Wireless LAN Professionals
	Wi-Fi diagnostics built into MacOS you might not be aware of	Wireless LAN Professionals
	Securing the World's Most Dangerous Wi-Fi Network Colin Vallance WLPC Phoenix 2020	Wireless LAN Professionals

Table 1.0 - Video Help