How Can I Troubleshoot Apple Internet
Functioning of Internet Addressing
When using the Internet, individuals may receive a Public IPv4 address such as 0.219.247.175 or an IPv6 address like 2000:40ae:1f88:1c8d:e59:ad66:a898:5494. This can be verified at https://test-ipv6.com/. However, communicating these addresses, or identifying MAC addresses like cd:49:10:c9:3b:a1, can be error-prone and complex for those who are not knowledgeable about technology. Moreover, this approach does not provide any historical data, particularly concerning past issues that may have occurred.
Navigating the Internet
In order to access a webpage, such as https://zieme-schumm.io, users initially connect to a DNS server to convert the host portion (zieme-schumm) along with the Top Level Domain (io) of the URL into an IP address like 27.64.141.55. When making web requests, your computer and browser actually sends its type information, such as Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Significance of Default Gateways
The default gateway is typically an address that is automatically configured via DHCP. You may receive a default gateway like 172.16.54.70 (although they typically end in .1 or .254 depending on the scope size) and this is the location where your computer sends all of its traffic to be routed onward. For IPv6 guidance, there is an in-depth exploration available at how-to-fix-ipv6-connectivity/, however, you can perform a check on Mac or Linux using 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 172.16.54.70 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:eea3:2b69:9e6c:83c5%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): {247.145.41.160, 94.24.217.149}
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 cd:49:10:c9:3b:a1
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 c7:ee:ed:f9:bc:05
}
Fixing Connection Issues for Wired and Wireless Networks
When it comes to transmitting data at the physical and data layer, you have the option of using either a wired or a wireless (Wi-Fi) medium to send the data to your router.
Troubleshooting Tips for Apple macOS / OSX
No matter which version of OSX/macOS you are using, whether it’s 10.11.9, 11.6.2, or 12.2.4, there are several tools available for troubleshooting. However, these manual actions and scripts do not provide a series of correlated values over time. This is where the benefits of automated remote troubleshooting come into play, especially for teams that are embracing remote work and Work From Anywhere (WFA).
Utilizing In-Built Scripts for Assistance
One useful tool on OSX/macOS is the sudo wdutil info, which provides a dump to the CLI of the current wireless settings and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although many of them are point-in-time only in relation to wireless, similar to wdutil.
To run it 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 use the command sudo /usr/bin/sysdiagnose, but be aware that it 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. Keep in mind that the file sizes are approximately 300MB.
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