DiagnOSe Mcs No Access
Understanding Internet Addressing
When using the Internet, you may be assigned a Public IPv4 address, such as 100.189.105.80, or an IPv6 address, such as 2000:212b:b8:32e3:7da4:a056:9f29:98eb. You can verify this information by visiting https://test-ipv6.com/. However, for individuals who are not well-versed in technology, communicating these addresses or even referencing MAC addresses, like b2:6a:a0:1d:8f:64, can be prone to errors and can become convoluted rather quickly. Moreover, this information does not provide any historical context, particularly in relation to past issues that may have arisen.
Navigating the World Wide Web
In order to access a webpage such as https://erdman-oconner.net, you first connect to a DNS server to convert the host portion (erdman-oconner) along with the Top Level Domain (net) of the URL into an IP address, such as 143.74.163.56. Your computer and browser include its type in all web requests, 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 automatically assigned address through DHCP. Usually, it is a default gateway like 172.20.70.122 (although they generally end in .1 or .254 depending on the scope size) and this is where your computer directs all its traffic to be routed further. For IPv6, you can find more detailed information on how-to-fix-ipv6-connectivity/ but you can check on Mac or Linux 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 172.20.70.122 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:c8df:61a8:2bed:f2cb%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): {120.108.13.171, 51.97.94.206}
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 b2:6a:a0:1d:8f:64
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 91:3e:b6:a5:40:ca
}
Resolve Connectivity Issues with Wired and Wireless Networks
When it comes to sending data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layers.
How to Address Problems on Apple macOS / OSX Systems
Regardless of whether you are running 10.11.4, 11.0.5, or 12.0.4, there are various troubleshooting tools available for OSX/macOS. However, these manual and scripted solutions do not provide a set of interconnected values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that embrace remote work and Work From Anywhere (WFA) policies.
Useful Built-in Scripts for Troubleshooting
A highly useful tool on OSX/macOS is sudo wdutil info, which provides a dump of the current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool offers a more comprehensive range of logs (although many are only point-in-time in relation to wireless, like wdutil).
To run it in the background and generate logs at /var/tmp/<blah>.tar.gz, use sudo nohup /usr/bin/sysdiagnose -u &. For an interactive option, you can run sudo /usr/bin/sysdiagnose, which will open Finder in the correct location or allow you to navigate to /var/tmp. Keep in mind that the file sizes will be around 300MB or slightly more.
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P.S. Tips For Remote Network and Client Support
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