Fix Apple Issues
The Functionality of Internet Addressing
When using the Internet, you can be assigned a Public IPv4 address such as 191.202.129.154 or an IPv6 address like 2000:1d4c:897:6290:97f2:b640:a4b3:8147. To confirm this, you can visit https://test-ipv6.com/. However, conveying these addresses to those who are not well-versed in technology, or even mentioning MAC addresses like de:9f:4b:94:9b:d6, can lead to errors and become complex. Moreover, this does not provide historical data, especially from previous issues.
Navigating the Internet
In order to reach a website like https://rippin-lehner.info, your device initially contacts a DNS server to convert the host portion (rippin-lehner) in combination with the Top Level Domain (info) of the URL to an IP address such as 99.235.9.234. Additionally, your computer and browser includes its type with all web requests e.g. 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 via DHCP. You receive a default gateway like 172.25.144.162 (although they typically end in .1 or .254 based on the scope size) and this is where your computer sends all its data to be routed further. For IPv6, you can find more detailed information on how-to-fix-ipv6-connectivity/, or you can verify on Mac or Linux 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 172.25.144.162 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 fe80:1cd3:6892:8684:4d0%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): {2.114.140.239, 137.111.187.118}
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 de:9f:4b:94:9b:d6
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 82:fb:75:62:b2:72
}
Fixing Wired and Wireless Connectivity Issues
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 Tips for Apple macOS / OSX
Regardless of the version of OSX/macOS you have, whether it’s 10.13.1, 11.3.4, or 12.3.3, there are a variety of troubleshooting tools available. However, manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes crucial, especially for teams that practice remote work and Work From Anywhere (WFA).
Useful Built-in Scripts for Troubleshooting
One useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Moreover, the sysdiagnose tool can be used to generate a comprehensive set of logs related to wireless issues, although much of it is only point-in-time data 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 &. If you prefer to run it interactively, use the command sudo /usr/bin/sysdiagnose. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp manually. Keep in mind that the file sizes are approximately 300MB.
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