Fix MacOS No-access
derstanding How Internet Addressing Functions
When using the Internet, you are assigned a Public IPv4 address, such as 162.114.122.6, or an IPv6 address, like 2000:f4c1:dfb3:a0c9:5d64:9082:5661:7c49. You can verify this information at https://test-ipv6.com/. However, communicating these addresses, as well as MAC addresses like 05:22:4c:9f:de:eb, can be prone to errors and quickly become complex, especially for individuals who are not tech-savvy. In addition, it does not provide historical data, particularly related to past issues.
Navigating the Internet and the Process of Lookups
Accessing a website such as https://beatty-hansen.com begins with connecting to a DNS server, which translates the host portion (beatty-hansen) in combination with the Top Level Domain (com) of the URL to an IP address, like 92.237.73.157. For all web requests, your computer and browser transmit their type, for example: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
The Significance of Default Gateways
Your default gateway is typically an address configured automatically via DHCP, such as 192.168.77.97 (although they often end in .1 or .254 based on the scope size). This is where your computer sends all of its traffic to be routed further. For IPv6, we provide an in-depth exploration at how-to-fix-ipv6-connectivity/, and it can be checked 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 192.168.77.97 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 fe80:1def:9959:360d:b8ec%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): {142.205.109.91, 102.246.98.135}
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 05:22:4c:9f:de:eb
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 ce:b5:d2:8f:f4:7c
}
Solutions for Wired and Wireless Connection Issues
When transferring data to your router, you may be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Effective Troubleshooting Methods for Apple macOS / OSX
Regardless of whether you are running OSX or macOS version 10.14.7, 11.3.7, or 12.2.9, there is a variety of troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting comes into play, especially for teams that practice remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts and Commands
A helpful tool for OSX/macOS is sudo wdutil info, which provides a dump of current wireless related settings to the CLI, and it can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although many relate to wireless issues just like wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can execute sudo /usr/bin/sysdiagnose, which 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 Cmd+Shift+G in Finder. Just be mindful of the file sizes, which are approximately 300MB.
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