How To Support Apple Internet
Explanation of Internet Address Structure
When using the Internet, individuals may be assigned a Public IPv4 address, such as 36.60.119.152, or an IPv6 address, such as 2000:de60:fc6b:b559:e766:6dd4:4423:e4f5. This information can be verified on https://test-ipv6.com/. However, explaining and communicating these addresses, as well as MAC addresses like c6:88:7e:a5:5b:68, can become complex and error-prone, especially for those who are not technologically savvy. Furthermore, this approach does not provide any historical data, particularly from previous issues.
Navigating the Internet
Accessing a website, such as https://murazik.info, requires an initial request to a DNS server in order to convert the host component (murazik) paired with the Top Level Domain (info) of the URL into an IP address, such as 196.229.26.134. It is worth noting that the computer and browser include specific information with each web request, for example, Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko.
Significance of Default Gateways
The default gateway is usually an address that is automatically obtained through DHCP. This default gateway, such as 192.0.0.88 (although they generally end in .1 or .254 based on the size of the scope), is where the computer directs all of its traffic to be routed. A detailed guide on how to handle IPv6 connectivity is available in our article how-to-fix-ipv6-connectivity/, but it can also be checked on Mac or Linux systems 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 192.0.0.88 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 fe80:4db:5540:4b7d:18a%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): {227.67.61.109, 92.117.149.138}
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 c6:88:7e:a5:5b:68
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 a8:e4:47:c1:d9:f6
}
Resolving Connectivity Issues in Wired and Wireless Networks
In the realm of physical and data layers, the utilization of either wired or wireless (Wi-Fi) mediums for transmitting data to your router is common.
Troubleshooting Guide for Apple macOS / OSX
Regardless of the version of OSX/macOS you are operating, such as 10.12.9, 11.0.7, or 12.0.4, there exists a wide array of tools available for addressing connectivity problems. However, the manual procedures and scripts do not provide a comprehensive set of correlated values over an extended period. This is where automated remote troubleshooting proves to be particularly valuable, especially for organizations that have embraced remote work and Work From Anywhere (WFA) practices.
Utilizing Built-in Scripts for Assistance
A highly useful tool on OSX/macOS is the sudo wdutil info command, which offers a dump of current wireless settings to the CLI and can also be configured to generate specific logs for troubleshooting purposes. Furthermore, the sysdiagnose tool can be employed to generate a multitude of logs, although much of the information is only relevant to a specific point in time with respect to wireless, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in /var/tmp/<blah>.tar.gz for the user. For an interactive execution (despite minimal interaction), the command sudo /usr/bin/sysdiagnose can be utilized, along with a privacy warning. When not run in the background, it should open Finder in the appropriate location, enabling the user to navigate to /var/tmp or employ Finder with Cmd+Shift+G to direct it to the specified path. It is important to note the file sizes, which are approximately 300MB more or less.
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