How Do You Test Apple Connectivity
Demystifying Internet Addressing
When using the Internet, you will be assigned a Public IPv4 address, such as 225.252.57.81, or an IPv6 address, such as 2000:6f31:3791:39e9:3fc0:1f86:3390:93ee. You can verify your assigned address at https://test-ipv6.com/. However, explaining these addresses, or even MAC addresses like 14:ae:23:42:72:f8, to individuals who are not familiar with technical jargon can lead to errors and confusion. Furthermore, this method does not provide any historical data, especially regarding past issues.
Navigating the World Wide Web
When attempting to access a website, such as https://greenholt.name, you first contact a DNS server to translate the host portion (greenholt) and the Top Level Domain (name) of the URL into an IP address, such as 67.167.248.10. Your computer and browser convey their type with each web request, for example: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
Understanding the Role of Default Gateways
Your default gateway is typically an address that is automatically configured through DHCP. This address, such as 10.255.219.98 (although they usually end in .1 or .254 based on the size of the scope), is where your computer directs all of its traffic to be routed elsewhere. For IPv6, you can find detailed instructions on how-to-fix-ipv6-connectivity/, or check 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 10.255.219.98 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 fe80:6ca:10dd:ed4f:9565%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): {28.28.229.101, 66.149.191.83}
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 14:ae:23:42:72:f8
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 24:c5:89:cf:53:06
}
Dealing with Wired and Wireless Connectivity Issues
When it comes to sending data to your router, you might be using either a wired or wireless (Wi-Fi) connection at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX Users
Regardless of whether you are using OSX/macOS version 10.14.8, 11.2.7, or 12.3.9, there are various troubleshooting tools available. 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 that are remote and embrace the Work From Anywhere (WFA) concept.
Useful Built-in Scripts
One useful tool for OSX/macOS users is sudo wdutil info, which provides a dump of current wireless settings to the command line interface. This tool can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a variety of logs, although much of it relates to wireless and is only point-in-time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & will execute the tool in the background and write logs to /var/tmp/<blah>.tar.gz. Alternatively, running it interactively by executing sudo /usr/bin/sysdiagnose will prompt a privacy warning. When not run in the background, it should open Finder in the correct location, or users can navigate to /var/tmp using Finder with Cmd+Shift+G. It is important to note that the file sizes are approximately 300MB.
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