How Do You Test Mac Issues
Understanding Internet Addressing
When you connect to the Internet, you are assigned a Public IPv4 address such as 26.38.49.81 or an IPv6 address like 2000:7f60:baab:c391:c824:d6c3:cb08:725a. You can verify this information at https://test-ipv6.com/. However, conveying these addresses to non-technical individuals, or even referencing MAC addresses like 97:ff:06:3d:03:68, can be prone to errors and can become complex. Additionally, this method does not provide historical data, particularly for past issues.
Navigating the Internet
When you want to visit a webpage such as https://cruickshank-bednar.org, you first contact a DNS server to convert the host portion (cruickshank-bednar) combined with the Top Level Domain (org) of the URL into an IP address like 151.34.56.155. Your computer and browser includes its type in all web requests, for example: Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
The Significance of Default Gateways
Your default gateway is typically an address assigned automatically via DHCP, such as 192.168.151.206 (although they usually end in .1 or .254 based on the scope size). This is where your computer sends all its traffic to be routed further. For IPv6, you can find more detailed information on how-to-fix-ipv6-connectivity/ but you can also check 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 192.168.151.206 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 fe80:13b3:7c71:1f58:6726%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): {147.82.243.54, 32.237.137.165}
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 97:ff:06:3d:03:68
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 51:73:5d:ba:21:df
}
Fixing Issues with Wired and Wireless Connections
When it comes to sending data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
Whether you’re on OSX/macOS version 10.12.5, 11.3.2, or 12.1.7, there are various tools available for troubleshooting. However, these manual actions and scripts don’t provide a set of correlated values over time. This is where automated remote troubleshooting becomes especially valuable, particularly for teams adapting to remote work and Work From Anywhere (WFA) practices.
Utilizing Built-in Scripts for Assistance
An extremely useful tool on OSX/macOS is the sudo wdutil info, which provides a dump of current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Furthermore, the sysdiagnose tool can be used to generate a wide range of logs, although it is primarily point-in-time data related to wireless, 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 (though minimal interaction is involved), you can execute sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. If 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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