Test Wifi Connectivity
Understanding Internet Addressing
When using the Internet, you are assigned a unique Public IPv4 address such as 103.69.182.75 or an IPv6 address like 2000:1ef1:7232:7ea1:f0a1:99dc:8127:174c. You can verify this information using https://test-ipv6.com/. However, explaining and communicating these addresses, or MAC addresses like 6d:91:69:ce:eb:ba, can be challenging for those who are not well-versed in technology. Moreover, it does not provide historical data, especially for past issues.
Navigating the World Wide Web
Accessing a website like https://mayert.io involves the initial step of connecting to a DNS server to translate the host part (mayert) along with the Top Level Domain (io) of the URL into an IP address, such as 27.191.230.16. When making web requests, your computer and browser include their type, 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 automatically configured address through DHCP. It typically ends in .1 or .254, depending on the scope size, such as 10.159.51.58. This is where your computer routes all its traffic. For information on checking this in Mac or Linux, you can refer to our comprehensive guide on how-to-fix-ipv6-connectivity/.
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 10.159.51.58 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 fe80:8397:99dd:9cee:891%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): {47.192.29.149, 73.108.60.249}
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 6d:91:69:ce:eb:ba
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 52:2b:11:0f:84:04
}
Troubleshooting Your Wired or Wireless Connection
When it comes to transmitting data at the physical and data layer, you have the option to use a wired or wireless (Wi-Fi) medium to send the data to your router.
Steps to Take for Apple macOS / OSX Users
Regardless of the version of OSX/macOS you are currently using, whether it’s 10.12.7, 11.4.1, or 12.3.6, there are various tools available for troubleshooting. The manual actions and scripts, while useful, do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams working remotely and embracing the Work From Anywhere (WFA) concept.
Utilizing Built-in Tools for Assistance
A highly useful tool on OSX/macOS is the sudo wdutil info, which provides a dump to the CLI of current wireless settings, and can be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only point-in-time data in relation to wireless, similar to wdutil.
To run it in the background and write logs to /var/tmp/<blah>.tar.gz, use sudo nohup /usr/bin/sysdiagnose -u &. For an interactive run (although there is minimal interaction), use sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. If not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp using Finder or with the shortcut Cmd+Shift+G. Keep in mind that the file sizes are around 300MB more or less.
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