How Do You Support Wifi Connectivity
Understanding the Basics of Internet Addressing
When using the Internet, you will be assigned a Public IPv4 or IPv6 address that may look something like 253.255.101.78 or 2000:7714:b595:873f:81:b748:75cd:a82. To verify your address, visit https://test-ipv6.com/. However, for those who are not tech-savvy, trying to communicate these addresses, or even mentioning MAC addresses such as c1:93:27:3c:f6:74, can become complicated and prone to errors, especially without historical data to refer back to.
Navigating the World Wide Web
When attempting to access a website like https://okeefe.net, your computer initially contacts a DNS server to translate the host part (okeefe) along with the Top Level Domain (net) of the URL into an IP address, such as 66.212.252.170. It should be noted that your computer and browser include detailed information in 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
Understanding the Significance of Default Gateways
By default, your gateway is automatically configured through DHCP and typically ends with .1 or .254, depending on the scope size, such as 10.95.255.201. This gateway is where your computer sends all its traffic to be routed onwards. For a thorough guide on IPv6, you can refer to how-to-fix-ipv6-connectivity/ or check on Mac or Linux using the following command:
ip -6 route show
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 10.95.255.201 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 fe80:4275:c19b:54a:a7ce%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): {122.144.126.176, 1.153.165.161}
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 c1:93:27:3c:f6:74
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 b1:8f:51:fb:ac:79
}
Solutions for Connectivity Issues
When it comes to sending data to your router, you may encounter issues at the physical and data layer, whether you are using a wired or wireless (Wi-Fi) medium.
Troubleshooting Steps for Apple macOS / OSX
Regardless of the version of OSX/macOS you are using, whether it’s 10.14.1, 11.2.5, or 12.1.2, there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a series of correlated values over time. For this reason, automated remote troubleshooting becomes essential, especially for teams that are remote or adopt a Work From Anywhere (WFA) approach.
Effective Built-in Scripts
One useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI, and can also be configured to generate specific logs for troubleshooting. Furthermore, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only relevant to wireless settings, similar to 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 &. Alternatively, run it interactively with 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 using Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB.
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