Troubleshoot Apple Issues
Understanding Internet Address Allocation
When you connect to the Internet, you are assigned a unique public IPv4 address, such as 152.134.216.136, or an IPv6 address, such as 2000:4b9f:74e7:9c20:6119:af96:5ac5:c7fd. To verify your Internet addressing, you can visit https://test-ipv6.com/. However, for those who are not familiar with technical aspects, relaying these addresses or even identifying MAC addresses like 3e:72:d9:93:7f:73 can be error-prone and complex. Furthermore, this method does not provide any historical data, especially for past issues.
Navigating the Internet
When you want to visit a webpage, such as https://zieme.co, your computer initially accesses a DNS server to translate the host (zieme) and the Top Level Domain (co) of the URL into an IP address, such as 94.6.165.60. Your computer and browser also include specific information with each web request, such as: Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Exploring the Significance of Default Gateways
The default gateway is typically an automatically assigned address through DHCP. You receive a default gateway address, such as 192.168.86.183 (often ending in .1 or .254 based on scope size), which is where your computer sends all traffic to be routed. For IPv6, we offer an extensive guide on how-to-fix-ipv6-connectivity/, and you can verify this on Mac or Linux by:
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 192.168.86.183 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 fe80:2a5a:3d4f:28a1:6387%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): {238.206.85.123, 151.92.143.145}
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 3e:72:d9:93:7f:73
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 a0:c0:39:5c:7e:f4
}
Resolving Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you may be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Strategies for Apple macOS / OSX
Regardless of whether you are running OSX/macOS versions like 10.13.9, 11.0.5, or 12.3.4, there are various troubleshooting tools available. However, these manual interventions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, particularly for teams that adopt remote work and Work From Anywhere (WFA) practices.
Utilizing Pre-installed Scripts for Assistance
On OSX/macOS, the command sudo wdutil info is a useful tool as it provides a dump of current wireless related settings to the CLI and can also be configured to generate specific logs for troubleshooting. Moreover, the sysdiagnose tool offers a more comprehensive solution by generating a wide range of logs, although many of these are only point-in-time data in relation 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 you. If you prefer to run it interactively, simply execute sudo /usr/bin/sysdiagnose, which will trigger a privacy warning. When 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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