How To Check Apple Connectivity
The Functionality of Internet Addressing
When using the Internet, you are assigned a Public IPv4 address, such as 28.17.244.158, or an IPv6 address, like 2000:95ee:f028:567d:e989:fb3c:581b:49ea. You can verify your address at https://test-ipv6.com/. However, conveying these addresses to individuals who are not technologically adept can lead to errors and complications, especially when dealing with MAC addresses, such as 78:d6:b1:a4:08:db. Furthermore, this method does not provide any historical data on past occurrences of issues.
Navigating the Internet
Accessing a website, such as https://schaden.org, involves an initial interaction with a DNS server to translate the host portion (schaden) combined with the Top Level Domain (org) into an IP address, such as 219.90.34.143. Additionally, your computer and browser send their type along with 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
The Significance of Default Gateways
Your default gateway is typically an address automatically configured via DHCP, such as 10.166.17.227 (usually ending in .1 or .254, depending on the scope size). This gateway is responsible for routing all your computer’s traffic. For IPv6, you can refer to our comprehensive guide on how-to-fix-ipv6-connectivity/, or check on Mac or Linux with the following command:
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 10.166.17.227 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 fe80:8233:5afc:9d3c:ac45%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): {228.83.108.150, 28.80.208.85}
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 78:d6:b1:a4:08:db
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 89:98:92:a1:ca:72
}
Resolve Issues with Wired or Wireless Connections
When it comes to the physical and data layer, you may be utilizing either a wired or wireless (Wi-Fi) medium to transmit data to your router.
Troubleshooting Solutions for Apple macOS / OSX
Regardless of the version of OSX/macOS you are using, whether it’s 10.13.8, 11.1.6, or 12.1.7, there are various tools available for resolving issues. However, these manual actions and scripts fall short in providing a series of correlated values over time. This is where automated remote troubleshooting becomes invaluable, particularly for teams that have adopted remote work and Work From Anywhere (WFA).
Embedded Scripts for Assistance
One extremely useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings to the CLI and can also be configured to generate specific logs for troubleshooting. Moreover, the sysdiagnose tool, while more comprehensive, can be utilized to generate a wide range of logs (although many are only relevant to wireless settings, similar to wdutil).
To run it in the background and have it write logs to /var/tmp/<blah>.tar.gz, use the commandsudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, simply use the commandsudo /usr/bin/sysdiagnose and it will prompt a privacy warning. When not run in the background, it should open Finder in the correct location, allowing you to navigate to /var/tmp or use Finder with Cmd+Shift+G to point Finder to the path. Take note of the file sizes, which are roughly around 300MB.
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