How Can I Support Apple Connectivity
Understanding the Function of Internet Addressing
When using the Internet, you are assigned a Public IPv4 address, such as 28.36.131.179, or an IPv6 address like 2000:6cdb:1ed4:9b3f:f2a9:15d:9eeb:b787. You can verify your address by visiting https://test-ipv6.com/. However, these addresses, including MAC addresses like 88:37:c5:e3:a8:d2, can be challenging for individuals without a technical background to communicate and remember. Furthermore, they do not provide historical data, particularly from previous incidents.
Navigating the Internet
When accessing a website, such as https://von-kuhlman.name, a request is made to a DNS server to translate the host portion (von-kuhlman) and the Top Level Domain (name) of the URL into an IP address like 10.6.50.198. Interestingly, your computer and browser send their type along with all web requests, as shown in the example: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
Significance of Default Gateways
The default gateway is typically assigned automatically through DHCP and is often a numeric address ending in .1 or .254, depending on the scope size, such as 192.168.28.249. This is where your computer directs all its traffic for routing. For IPv6, detailed information on resolving connectivity issues can be found at how-to-fix-ipv6-connectivity/. Additionally, on Mac or Linux systems, verification can be performed by 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 192.168.28.249 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 fe80:199:aa88:a656:7825%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): {211.122.153.242, 45.56.70.235}
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 88:37:c5:e3:a8:d2
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 ef:67:c1:4d:41:3b
}
Fixing Connectivity Issues for Wired and Wireless Networks
When it comes to transmitting data to your router, you may be using either a wired or a wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple’s macOS / OSX Systems
Irrespective of whether you are running OSX/macOS versions such as 10.12.1, 11.1.2, or 12.3.5, there is a variety of 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, particularly for teams that are in favor of remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
A highly useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings to the command-line interface and can be configured to generate specific logs for troubleshooting. Furthermore, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only relevant to the point in time in relation to wireless, similar to wdutil.
To run sysdiagnose in the background and write logs to /var/tmp/<blah>.tar.gz, you can use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can run sudo /usr/bin/sysdiagnose, which 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 using Finder with Cmd+Shift+G to point Finder to the path. However, be cautious of the file sizes, which are about 300MB more or less.
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