Test Apple IP Settings
The Function of Internet Addressing
When using the Internet, it is possible to obtain a Public IPv4 address such as 97.187.36.43 or an IPv6 address such as 2000:94dc:cbf8:dc48:56d4:5ab0:1630:1a5f. This information can be verified at https://test-ipv6.com/. However, attempting to convey these addresses to individuals who are not well-versed in technology, or even recite MAC addresses like 52:89:fa:8c:6e:90, can be prone to errors and become complex rather swiftly. Moreover, this method does not provide historical data, particularly from the time when previous issues arose.
Navigating the Internet
In order to access a website such as https://schaefer.org, the first step is to contact a DNS server, which will convert the host portion (schaefer) combined with the Top Level Domain (org) of the URL into an IP address such as 48.66.107.192. When making web requests, your computer and browser actually send their type, for example: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
The Significance of Default Gateways
Typically, your default gateway is an address that is automatically configured via DHCP. This results in obtaining a default gateway such as 192.168.217.247 (although they usually end in .1 or .254 based on the size of the scope). This is the destination where all of your computer’s traffic is sent to be routed further. For a detailed examination of IPv6, refer to our comprehensive guide on how-to-fix-ipv6-connectivity/. However, you can also check on Mac or Linux using the following command:
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 192.168.217.247 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 fe80:854e:c9fb:4fa8:29d3%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): {130.208.24.236, 13.24.145.240}
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 52:89:fa:8c:6e:90
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 66:df:50:92:ba:75
}
Resolve Issues with Wired or Wireless Connections
When it comes to transmitting data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting on Apple macOS / OSX Systems
Regardless of the version of OSX/macOS you are operating on, whether it’s 10.12.5, 11.5.2, or 12.0.6, there are various tools available for resolving issues. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes essential, especially for teams that practice 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 CLI and can be configured to generate specific troubleshooting logs. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, though much of it is only relevant to wireless 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 you. Alternatively, you can run sudo /usr/bin/sysdiagnose interactively, which will provide a privacy warning and open Finder in the correct location. Just be cautious of the file sizes, which can be around 300MB.
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