How Can I Support MacOS Internet
Understanding Internet Addressing
When using the Internet, it is common to have a Public IPv4 address such as 30.83.110.247 or the longer IPv6 address like 2000:9688:46ec:2b77:23f7:4c5:2a1d:e7eb. You can verify your address at https://test-ipv6.com/. However, these addresses, as well as MAC addresses like e8:f1:66:9f:17:bd, can be challenging for non-technical individuals to use and communicate effectively without errors. Moreover, they do not provide historical data, particularly when addressing past issues.
Navigating the Internet
When accessing a website, such as https://turner.com, your computer initially contacts a DNS server to translate the URL’s host portion (turner) and Top Level Domain (com) into an IP address like 102.90.18.159. In addition, your computer and browser include their specifications in all web requests, such as Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A.
The Significance of Default Gateways
Your default gateway is typically an automatically provided address through DHCP, such as 192.168.59.154 (although it commonly ends in .1 or .254 depending on the scope size). This gateway is where your computer sends all its traffic to be routed onwards. For IPv6, detailed instructions can be found at how-to-fix-ipv6-connectivity/, but you can check on Mac or Linux with the following commands:
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 192.168.59.154 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 fe80:7483:4f33:921f:4f28%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): {129.47.216.141, 212.207.59.133}
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 e8:f1:66:9f:17:bd
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 86:f5:04:85:6a:84
}
Fixing Connectivity Issues for Wired and Wireless Networks
When it comes to transmitting data to your router, you have the option of using a wired or wireless (Wi-Fi) medium at the physical and data layer.
Resolving Issues on Apple macOS / OSX
Irrespective of the version of OSX/macOS you are using, whether it’s 10.12.2, 11.6.2, or 12.1.8, there are various 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 valuable, particularly for teams that endorse remote work and Work From Anywhere (WFA).
Utilizing Built-in Tools for Assistance
One highly 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 set up to generate specific logs for troubleshooting. Furthermore, the sysdiagnose tool can be used to generate a wide array of logs, albeit most of the information is only relevant to the wireless at a specific point in time, much like wdutil.
To run the sysdiagnose tool in the background and generate logs at /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 use the command sudo /usr/bin/sysdiagnose, which will display a privacy warning. When not run in the background, the tool should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. Be mindful of the file sizes, which are approximately 300MB each.
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