How Do You Test OSX Issues
The Functionality of Internet Addressing
When using the Internet, individuals can have either a Public IPv4 address, such as 106.192.31.204, or an IPv6 address, like 2000:883f:2749:bd5:68ae:e057:bbb7:b5fe. Verification of these addresses can be conducted at https://test-ipv6.com/. Communicating these addresses to those who are not technologically savvy, or even mentioning MAC addresses like b4:b3:ba:bf:4e:62, can quickly become complex and prone to errors. Furthermore, it does not provide any historical data, especially when dealing with past issues.
Navigating the Internet
In order to access a webpage, such as https://batz.name, individuals must first connect to a DNS server, which translates the host portion (batz) combined with the Top Level Domain (name) of the URL into an IP address, such as 192.196.63.251. With each web request, the type of computer and browser is actually sent, for example: Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16.
The Significance of Default Gateways
Typically, a default gateway is an automatically configured address via DHCP. Individuals receive a default gateway, such as 192.168.89.99 (although they usually end in .1 or .254 depending on the scope size), to which their computer forwards all traffic to be routed onwards. For IPv6, a detailed guide on how-to-fix-ipv6-connectivity/ is available, and verification can be done on Mac or Linux by 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 192.168.89.99 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:b329:c948:f46:1573%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): {231.188.128.236, 167.50.27.154}
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 b4:b3:ba:bf:4e:62
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 c5:27:a9:d9:45:14
}
Resolving Connectivity Issues for Wired and Wireless Networks
When it comes to transmitting data to your router, you may be utilizing either a wired or a wireless (Wi-Fi) connection at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX Users
Regardless of whether you are running OSX/macOS versions like 10.15.2, 11.1.8, or 12.3.4, there are various troubleshooting tools available. However, these manual methods and scripts do not provide a continuous set of related values over time. This is where remote automated troubleshooting becomes valuable, especially for teams that have embraced remote work and Work From Anywhere (WFA).
Helpful Built-in Scripts
One useful tool on OSX/macOS is the sudo wdutil info command, which displays the current wireless settings and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to produce a wide range of logs, although much of it is only relevant to wireless settings at a specific point in time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz. For an interactive run (despite minimal interaction), you can use sudo /usr/bin/sysdiagnose and it will issue a privacy warning. If not run in the background, it will open Finder in the correct location, or you can navigate to /var/tmp using Cmd+Shift+G in Finder. Keep in mind that the file sizes will be approximately 300MB.
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