How Do You Check Apple Issues
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 address such as 56.107.156.166 or an IPv6 address like 2000:b29b:340d:392a:b67b:e4e5:1e5:d6c5. These addresses can be verified at https://test-ipv6.com/. However, explaining these addresses to individuals who are not tech-savvy, or even mentioning MAC addresses like 32:91:9f:19:be:66, can lead to errors and complexity. Furthermore, it does not offer any historical data, especially from previous issues.
Navigating the Web
In order to access a website, for example, https://walsh.co, your initial step is to contact a DNS server to convert the host part (walsh) along with the Top Level Domain (co) of the URL into an IP address like 221.106.214.218. Your computer and browser sends its type with each web request such as Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Significance of Default Gateways
A default gateway is typically an address configured automatically via DHCP. It provides a default gateway like 192.0.0.125 (although they usually end in .1 or .254 based on the scope size) where your computer forwards all its traffic to be routed further. For IPv6, in-depth information is available at how-to-fix-ipv6-connectivity/, while on Mac or Linux, it can be checked with:
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 192.0.0.125 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 fe80:1abb:6e12:f965:4d4%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): {246.56.51.154, 112.131.56.232}
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 32:91:9f:19:be:66
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 35:d4:d1:f8:c3:27
}
Troubleshooting Connectivity Issues in Wired and Wireless Networks
When it comes to sending data from your device to your router, you may be using a wired or wireless (Wi-Fi) connection at the physical and data layer.
Resolving Connections Problems on Apple macOS / OSX
Regardless of the version of OSX/macOS you are running, whether it’s 10.14.3, 11.1.9, or 12.0.9, there are a variety of tools available for troubleshooting connectivity issues. However, these manual actions and scripts may not provide a series of correlated values over time. This is where automated remote troubleshooting becomes essential, especially for teams that are embracing remote work and Work From Anywhere (WFA) initiatives.
Using Built-in Scripts for Assistance
One valuable tool for OSX/macOS users is the sudo wdutil info command, which provides a dump of current wireless settings via the command line interface and can be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although many are only relevant to wireless connectivity, 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 approach, you can run sudo /usr/bin/sysdiagnose, which will display 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 or with Cmd+Shift+G. Keep in mind that the file sizes will be around 300MB.
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