How To Check Apple Issues
Understanding Internet Addressing
When using the Internet, you are assigned a unique Public IPv4 address like 83.176.98.62 or an IPv6 address like 2000:79a6:a587:5f4a:2b3f:a85b:b318:330c. You can verify this information by visiting https://test-ipv6.com/. However, explaining and communicating these addresses to individuals who are not well-versed in technology, as well as identifying MAC addresses like 4d:d1:4a:b1:14:0d, can be prone to errors and can become complex. Additionally, this method does not provide any historical data, especially when issues have occurred in the past.
Navigating the World Wide Web
In order to access a website such as https://wisozk.org, you initially connect to a DNS server to convert the host portion (wisozk) combined with the Top Level Domain (org) of the URL into an IP address like 11.135.234.111. Interestingly, your computer and browser transmit their type with every web request, for example: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
The Significance of Default Gateways
The default gateway is typically an automatically assigned address through DHCP. It is usually an address like 192.168.210.26 (although they often end in .1 or .254 based on the scope size), and this is the location where your computer sends all of its traffic to be routed further. For IPv6, detailed instructions are available on how-to-fix-ipv6-connectivity/, but on Mac or Linux, you can confirm this by running:
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 192.168.210.26 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:d7bb:ce2:bc4f:2109%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): {50.211.154.56, 22.110.49.30}
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 4d:d1:4a:b1:14:0d
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 a3:cf:92:8b:19:2d
}
Resolve Connectivity Issues in Wired and Wireless Networks
When transmitting data to your router, you may utilize either a wired or wireless (Wi-fi) medium at the physical and data layer.
Effective Solutions for macOS Users
Regardless of whether you are running OSX/macOS versions such as 10.11.4, 11.0.9, or 12.2.5, there are various troubleshooting tools available. However, these manual interventions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that embrace remote work and Work From Anywhere (WFA).
Useful Built-in Tools for Troubleshooting
One incredibly useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of the current wireless settings to the CLI. It can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool offers a comprehensive range of logs related to wireless, although much of the information is only relevant to a specific point in time, similar to wdutil.
To run the sysdiagnose tool in the background and generate logs in /var/tmp/<blah>.tar.gz, use the following command: sudo nohup /usr/bin/sysdiagnose -u &. Alternatively, you can run it interactively with the command: sudo /usr/bin/sysdiagnose, which will provide 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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