How Do You Check Apple No-access
Understanding Internet Addressing
When using the Internet, it is common to have a Public IPv4 address such as 251.101.50.60 or an IPv6 address like 2000:ddd6:af45:7444:960a:aed:a7b3:f0a4. You can verify this information at https://test-ipv6.com/. However, explaining and communicating these addresses, or even referencing MAC addresses like 81:fb:6e:c7:43:ba, can be tricky and prone to errors. In addition, it does not provide any historical data, especially when dealing with past issues.
Navigating the World Wide Web
In order to access a website such as https://ledner-gusikowski.info, the first step is to connect to a DNS server to translate the host portion (ledner-gusikowski) combined with the Top Level Domain (info) of the URL into an IP address, such as 46.52.168.128. Whenever a web request is made, your computer and browser also send their specifications, for example: Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Significance of Default Gateways
The default gateway is typically an address automatically configured via DHCP. This default gateway, such as 10.146.64.204 (usually ending in .1 or .254 depending on the scope size), is where your computer directs all its traffic to be routed. For IPv6, a detailed explanation is available at how-to-fix-ipv6-connectivity/. On Mac or Linux systems, this can be checked 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 10.146.64.204 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 fe80:1d10:238b:56b4:e913%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): {130.43.154.198, 102.226.245.169}
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 81:fb:6e:c7:43:ba
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 7b:89:c0:54:97:c7
}
Resolving Issues with Wired and Wireless Connections
When it comes to transferring data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
Regardless of whether you are running OSX/macOS versions such as 10.12.1, 11.4.4, or 12.3.1, 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 essential, especially for teams embracing remote work and Work From Anywhere (WFA) practices.
Useful Built-in Scripts
One valuable tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless related settings to the CLI and can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, though much of it is only relevant to wireless settings, similar to wdutil.
To run sysdiagnose in the background and write logs to /var/tmp/<blah>.tar.gz, you can use the command sudo nohup /usr/bin/sysdiagnose -u &. For an interactive option, you can run sudo /usr/bin/sysdiagnose, which will give a privacy warning and open Finder in the correct location. Keep in mind that the file sizes are approximately 300MB.
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