Check Common Wifi No Access
Understanding How the Internet Addressing System Functions
When using the Internet, you are assigned a Public IPv4 address, such as 60.220.117.116, or an IPv6 address, like 2000:e869:5461:f770:f67f:ac7f:9b14:9594. Verification of this information can be done at https://test-ipv6.com/. However, conveying these addresses to individuals who are not technologically inclined can be error-prone and complicated, especially when dealing with MAC addresses like 32:b0:11:1f:08:30. Additionally, this method does not provide historical data from previous occurrences.
Navigating the World Wide Web
In order to access a webpage, such as https://thompson.io, you first connect to a DNS server to translate the host portion (thompson) in combination with the Top Level Domain (io) of the URL to an IP address, such as 119.225.184.0. Your computer and browser include its type 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
Typically, your default gateway is automatically configured through DHCP and you are assigned an address such as 10.139.43.252 (although they typically end in .1 or .254 based on the scope size), which serves as the destination for all your computer’s outgoing traffic. For a detailed analysis on IPv6, refer to how-to-fix-ipv6-connectivity/. On Mac or Linux, you can verify this using the following command:
ifconfig | grep inet6
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 10.139.43.252 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 fe80:4d0:46fc:10b3:e51c%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): {57.151.106.47, 255.27.113.247}
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 32:b0:11:1f:08:30
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 8c:b6:63:64:b5:23
}
Addressing Connectivity Issues for Wired and Wireless Networks
When it comes to transmitting data to your router, you might be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple’s macOS
Regardless of whether you are running OSX/macOS version 10.15.4, 11.6.4, or 12.2.2, there are several tools available for troubleshooting. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams adopting remote work and the Work From Anywhere (WFA) approach.
Useful Built-in Utilities
One valuable tool on OSX/macOS is the sudo wdutil info command, which provides a dump of the current wireless settings to the CLI and can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to create a wide range of logs, although many are only relevant to a specific point in time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz for you. Alternatively, you can run sudo /usr/bin/sysdiagnose interactively (although there is minimal interaction) 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 or use Finder with Cmd+Shift+G to locate the path. However, be mindful of the file sizes, which are approximately 300MB.
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