How To Support Apple Internet Connection
Understanding the Functioning of Internet Addressing
When using the Internet, individuals may have Public IPv4 addresses such as 229.26.25.16 or IPv6 addresses like 2000:606d:86af:7988:c468:606d:f113:6ce1. This information can be verified at https://test-ipv6.com/. However, for those who are not technologically inclined, communicating these addresses or MAC addresses like ba:27:77:66:4c:54 can be prone to error and quickly becomes complex. Moreover, this method does not provide any historical data, especially for previous issues.
Navigating the Internet
When attempting to access a website, such as https://harvey-muller.biz, an individual initially connects to a DNS server to convert the host segment (harvey-muller) along with the Top Level Domain (biz) of the URL to an IP address, such as 234.69.42.50. Every web request from the user’s computer and browser contains information regarding its type, for example: Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)
The Significance of Default Gateways
A default gateway is typically an address that is automatically configured via DHCP. Users receive a default gateway, such as 192.168.55.9 (commonly ending in .1 or .254 based on the scope size), which serves as the central point where their computer sends all traffic to be routed elsewhere. For IPv6, a comprehensive guide on how-to-fix-ipv6-connectivity/ is available, and users on Mac or Linux systems can verify this by 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 192.168.55.9 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 fe80:50ad:f661:9e94:133d%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): {162.158.145.47, 159.169.194.253}
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 ba:27:77:66:4c:54
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 9c:f4:b3:8a:04:33
}
Resolving Connection Issues in Wired and Wireless Networks
When it comes to transmitting data, you may utilize either a wired or wireless (Wi-Fi) medium at the physical and data layer to send the data to your router.
Troubleshooting Tips for Apple macOS / OSX
Regardless of whether you are using OSX/macOS 10.15.6, 11.5.5, 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, which is where automated remote troubleshooting becomes invaluable, especially for teams engaging in remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
A useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of the current wireless-related settings in the command line interface 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, albeit mostly point-in-time logs in relation to wireless, similar to wdutil.
To run it in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. Alternatively, for interactive use, you can run sudo /usr/bin/sysdiagnose and navigate to the correct location in Finder or through the path /var/tmp. However, be cautious of the file sizes, which can be around 300MB.
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