How To Troubleshoot Mac No-access

Explanation of Internet Addressing When using the Internet, you are assigned a Public IPv4 or IPv6 address such as 39.61.200.13 or 2000:5146:ed56:a042:431a:2c5c:e317:a107. You can verify this by visiting https://test-ipv6.com/. However, conveying these addresses to individuals who are not technologically inclined can be prone to errors and can become complex, especially when dealing with MAC addresses like ab:c1:7a:f2:d8:0a. Explanation of Internet Addressing When using the Internet, you are assigned a Public IPv4 or IPv6 address such as 39.61.200.13 or 2000:5146:ed56:a042:431a:2c5c:e317:a107. You can verify this by visiting https://test-ipv6.com/. However, conveying these addresses to individuals who are not technologically inclined can be prone to errors and can become complex, especially when dealing with MAC addresses like ab:c1:7a:f2:d8:0a.

Explanation of Internet Addressing

When using the Internet, you are assigned a Public IPv4 or IPv6 address such as 39.61.200.13 or 2000:5146:ed56:a042:431a:2c5c:e317:a107. You can verify this by visiting https://test-ipv6.com/. However, conveying these addresses to individuals who are not technologically inclined can be prone to errors and can become complex, especially when dealing with MAC addresses like ab:c1:7a:f2:d8:0a. Moreover, it does not provide any historical data, particularly from previous issues.

When you want to visit a website such as https://haag.net, your computer first contacts a DNS server to convert the host portion (haag) along with the Top Level Domain (net) of the URL to an IP address, for example, 136.201.236.59. During this process, your computer and browser include details about its type in all web requests, for example:

Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0

Significance of Default Gateways

Your default gateway is typically an automatically assigned address through DHCP, such as 172.24.106.98 (though they commonly end in .1 or .254 depending on the scope size). This is the point where your computer sends all its traffic to be routed further. For IPv6, you can refer to a detailed explanation in our post how-to-fix-ipv6-connectivity/; alternatively, you can check on Mac or Linux with the following command:

ip -6 route

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  172.24.106.98    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   fe80:8e06:34c5:3717:48be%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): {68.177.47.29, 193.70.133.113}
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 ab:c1:7a:f2:d8:0a
  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 cd:dd:a8:17:4f:ce
}

Resolving Issues with Wired and Wireless Connections

When it comes to transmitting data to your router, you may rely on either a wired or wireless (Wi-Fi) medium at the physical and data layer.

Troubleshooting Steps for Apple macOS / OSX

No matter which version of OSX/macOS you’re using - whether it’s 10.15.8, 11.3.4, or 12.1.2 - there are a variety of tools available for troubleshooting. However, these manual actions and scripts fail to provide a series of correlated values over time. This is where automated remote troubleshooting becomes invaluable, particularly for teams embracing remote work and Work From Anywhere (WFA).

Useful Built-in Scripts

One particularly useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the command line interface, and can be configured to generate specific logs for troubleshooting. In addition, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only related to wireless at a specific point in time, similar to wdutil.

Running sudo nohup /usr/bin/sysdiagnose -u & will execute it in the background and write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (although there isn’t much interaction), you can run sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to direct Finder to the path. Just be mindful of the file sizes, which are around 300MB or so.

Possibly Helpful Videos

Video Title Channel
Securing macOS Big Sur Hands-On Mac
Secret Mac Boot Commands - Mac Boot Key Combinations Hands-On Mac
Spotlight on Spotlight - Hands-On Mac 7 Hands-On Mac
macOS Big Sur - What's New in Apple macOS 11 Hands-On Mac
On the Road to Big Sur 2 - Compatibility Hands-On Mac
Table 1.0 - Video Help



P.S. PanSift Tip For Work From Anywhere Support

Digital work requires reliable connectivity for voice, video, and data. Inevitable Wi-Fi, network, and system issues cause teams to lose time and productivity, or worse, to miss out on opportunities. Whether working from home, a shared space, or an office, and irrespective of the network being managed or unmanaged, forward thinking technical teams embrace smarter tools to save their users and clients time and money! See how PanSift provides instant remote troubleshooting, irrespective of location 🏠🏝🛰.

Design Benefits + 2 Free Agents


Rapid Digital Experience Monitoring for teams and tribes!

Instant Agent

2 x free macOS agents

Live Demo

No registration, immediate live demo!