How Do You Understand Mac No-access

Understanding Internet Addressing When using the internet, you are assigned a public address which could be either a Public IPv4 address, such as 122.211.230.133, or an IPv6 address, like 2000:95a7:f628:12ec:efb6:9d8e:2bbc:2b5e. https://test-ipv6.com/ can be used to check your assigned address. Understanding Internet Addressing When using the internet, you are assigned a public address which could be either a Public IPv4 address, such as 122.211.230.133, or an IPv6 address, like 2000:95a7:f628:12ec:efb6:9d8e:2bbc:2b5e. https://test-ipv6.com/ can be used to check your assigned address.

Understanding Internet Addressing

When using the internet, you are assigned a public address which could be either a Public IPv4 address, such as 122.211.230.133, or an IPv6 address, like 2000:95a7:f628:12ec:efb6:9d8e:2bbc:2b5e. https://test-ipv6.com/ can be used to check your assigned address. However, the challenge arises when trying to communicate and relay these addresses to individuals with limited technical expertise, especially when trying to call out complicated MAC addresses such as 15:ee:8e:19:7a:4c. In addition, there is no historical data provided for identifying recurring issues.

When attempting to access a web page, such as https://heathcote.name, the process initially involves connecting to a DNS server, which translates the chosen domain name (heathcote) along with the Top Level Domain (name) of the URL to an IP address, such as 225.179.124.3. Remarkably, the browser and computer communicate specific details along with every web request, for example:
Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)

Significance of Default Gateways

The default gateway is typically an automatically assigned address through DHCP. The default gateway, such as 192.0.0.35 (commonly ending in .1 or .254 based on scope size), serves as the primary routing destination for all computer traffic. While troubleshooting connectivity issues for IPv6, detailed information can be found at how-to-fix-ipv6-connectivity/. On Mac or Linux, the default gateways can be verified 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  192.0.0.35    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:b8a2:e4a4:fe4:ac44%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): {114.208.143.231, 50.46.60.212}
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 15:ee:8c:19:7a:4c
  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 01:91:ef:09:85:7b
}

Fixing Connectivity Issues for Wired and Wireless Networks

When transmitting 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

Regardless of the version of OSX/macOS you are using, whether it’s 10.14.1, 11.5.5, or 12.1.9, there are various 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 becomes valuable, especially for teams that embrace remote work and Work From Anywhere (WFA).

Utilizing In-Built Scripts for Assistance

One useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI and can be configured to generate specific troubleshooting logs. Additionally, the sysdiagnose tool can be used to generate a wide range of logs (although much of it is point in time only in relation to wireless, 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 point Finder to the path. Just be aware of the file sizes, which are approximately 300MB more or less.



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