How Do You Test Apple IP Settings
Understanding the Function of Internet Addressing
When connecting to the Internet, you will be assigned a public IP address, such as 191.20.94.60 for IPv4 or 2000:d53:11a2:63cd:36e1:f63a:92bc:a4d0 for IPv6. This can be verified by visiting https://test-ipv6.com/. However, explaining these addresses, including MAC addresses like a2:d5:7e:bc:fa:70, to those unfamiliar with technical terminology can lead to errors and complexity. Moreover, it does not provide any historical data, particularly when tracing past issues.
Navigating the Internet
Accessing a webpage, such as https://walsh.com, involves initially contacting a DNS server to convert the URL’s host portion (walsh) in combination with its Top Level Domain (com) into an IP address, like 49.73.222.180. When making web requests, your computer and browser both send their type, 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
By default, your gateway is assigned an address automatically through DHCP, such as 10.177.29.16 (typically ending in .1 or .254 based on the scope size), and serves as the point where your computer forwards all its traffic for routing. More information on troubleshooting IPv6 connectivity can be found in our in-depth guide at how-to-fix-ipv6-connectivity/. Instructions for Mac or Linux verification are also available.
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 10.177.29.16 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 fe80:5695:9aaa:d091:7317%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): {14.95.33.161, 167.222.53.135}
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 a2:d5:7e:bc:fa:70
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 7a:af:91:9d:f4:96
}
Troubleshooting Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
How to Address Problems on Apple macOS / OSX
Regardless of whether you are using OSX/macOS 10.12.6, 11.6.4, or 12.2.3, there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a set of interconnected values over time. This is where automated remote troubleshooting becomes essential, especially for teams that adopt remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
One useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Another tool, the sysdiagnose tool, can be used to generate a wide range of logs, although much of it is only relevant to wireless at a specific point in time, similar to wdutil.
To run the sysdiagnose tool in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, use the command sudo /usr/bin/sysdiagnose, but be aware that the file sizes can reach around 300MB. After running the command, it should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G.
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