How Do You Support OSX Connectivity
Explanation of Internet Addressing System
When connecting to the Internet, you are assigned a Public IPv4 address, such as 14.51.96.81, or an IPv6 address, like 2000:445:4ef6:5aee:2695:13b6:24be:cd7a. You can verify this by visiting https://test-ipv6.com/. However, conveying these addresses, as well as MAC addresses, such as 4f:3e:59:55:d7:f9, can be prone to errors, especially for non-technical individuals. Additionally, it does not provide any historical data.
Procedure for Accessing Websites
To access a website, such as https://kassulke.info, you first contact a DNS server to translate the host (kassulke) and the Top Level Domain (info) of the URL to an IP address, like 81.245.131.96. Every time your computer and browser send their types with 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.
Significance of Default Gateways
Your default gateway is typically an automatically configured address via DHCP. You receive a default gateway, such as 10.185.182.177 (usually ending in .1 or .254 depending on the scope size), to which your computer forwards all its traffic. For IPv6, we offer an in-depth guide on how-to-fix-ipv6-connectivity/, but you can verify it 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 10.185.182.177 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:ca7c:f312:2f48:dac8%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): {21.65.86.36, 246.69.141.13}
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 4f:3e:59:55:d7:f9
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 1c:a4:7a:9b:32:92
}
Resolve Wired and Wireless Connectivity Issues
Whether you are utilizing a wired or wireless (Wi-Fi) connection to transmit data to your router, issues at the physical and data layer can arise.
Troubleshooting Tips for Apple macOS / OSX
Regardless of the version of OSX/macOS you are running, be it 10.14.7, 11.4.7, or 12.3.5, there is a variety of troubleshooting tools available. However, these manual actions and scripts do not provide a consistent set of correlated values over time. This is where automated remote troubleshooting becomes valuable, particularly for teams that embrace remote work and Work From Anywhere (WFA).
In-Built Scripts for Assistance
One useful tool in OSX/macOS is sudo wdutil info, which offers a dump of current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can generate a wide range of logs, although much of it is only relevant to wireless settings at a specific point in time, similar to wdutil.
By running sudo nohup /usr/bin/sysdiagnose -u & in the background, logs will be written to /var/tmp/<blah>.tar.gz. For an interactive mode (although there is minimal interaction), you can run sudo /usr/bin/sysdiagnose, which will prompt 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. However, be cautious of file sizes, which can be around 300MB.
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