Troubleshoot Mcs No Access

Understanding Internet Addressing

When using the Internet, you are assigned a Public IPv4 address, such as 233.246.1.242, or an IPv6 address like 2000:54fb:919b:3c7f:8604:403e:ca41:6db9. You can verify this information by visiting https://test-ipv6.com/. However, conveying these addresses to non-technical individuals, or even mentioning MAC addresses like 2a:91:3f:c5:c9:d8, can be prone to errors and can become complex quite quickly. Furthermore, this method does not provide any historical data, especially when documenting past issues.

Navigating the World Wide Web

When accessing a website, such as https://ullrich.co, your computer initially communicates with a DNS server to translate the host portion (ullrich) combined with the Top Level Domain (co) of the URL into an IP address, such as 56.68.146.120. Additionally, your computer and browser automatically send their type with all web requests, for example: Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285

The Significance of Default Gateways

Your default gateway is typically an address that is automatically configured via DHCP. This address, such as 10.141.91.71 (although they normally end in .1 or .254 depending on the scope size), is where your computer forwards all its traffic to be routed onwards. For IPv6, you can find more detailed information at how-to-fix-ipv6-connectivity/. On Mac or Linux systems, you can check this 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  10.141.91.71    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   fe80:3065:52e2:2af3:d2e0%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): {170.106.186.107, 2.234.211.150}
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 2a:91:3f:c5:c9:d8
  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 88:41:7c:0b:d0:e0
}

Resolving Issues with Wired and Wireless Connections

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

Strategies for Apple macOS / OSX Users

No matter which version of OSX/macOS you’re running - whether it’s 10.11.2, 11.6.5 or 12.3.6 - there are various troubleshooting tools available. However, these manual actions and scripts fail to provide a series of correlated values over time. This is where automated remote troubleshooting becomes essential, particularly for teams that have embraced remote work and Work From Anywhere (WFA).

Utilizing In-Built Scripts for Assistance

One particularly 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 logs for troubleshooting. Moreover, the “sysdiagnose” tool offers a more comprehensive approach, creating a wide range of logs (though much of it is only relevant to wireless at a specific moment, similar to wdutil).

To run it in the background and generate logs to “/var/tmp/.tar.gz,” use the command “sudo nohup /usr/bin/sysdiagnose -u &.” If you prefer to run it interactively, you can use “sudo /usr/bin/sysdiagnose,” which will provide a privacy warning. Running it without background execution should open Finder in the correct location, or you can navigate to “/var/tmp” manually or using Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB.

Possibly Helpful Videos

Video	Title	Channel
	What Problem is UWB Trying to Solve with Stephen Cooper	Wireless LAN Professionals
	Hotspot 2.0 WLPC Wireless LAN Weekly EP 49	Wireless LAN Professionals
	Solving Wi-Fi problems in record time John Anderson WLPC US Phoenix 2017	Wireless LAN Professionals
	Benefits of WPA3, Enhanced Open, and Easy Connect P. Ebbecke, P. Correll WLPC Prague 2018	Wireless LAN Professionals
	Wi-Fi diagnostics built into MacOS you might not be aware of	Wireless LAN Professionals

Table 1.0 - Video Help