Fix Apple Internet Connection
Understanding Internet Addressing
When connecting to the Internet, you will be assigned either a Public IPv4 address, such as 8.191.15.252, or an IPv6 address, such as 2000:7ed4:4219:2d11:f00d:fe2a:5bb4:c2ae. This information can be verified through https://test-ipv6.com/. However, conveying and understanding these addresses, as well as MAC addresses like 8f:96:a4:a8:7f:b0, can become intricate and prone to errors. Moreover, these details do not provide any historical data, especially during previous issues.
Navigating through the Web
To access a webpage, for example, https://greenfelder.com, your computer first communicates with a DNS server to convert the host portion (greenfelder) combined with the Top Level Domain (com) of the URL into an IP address, such as 247.172.81.27. In addition, your computer and browser send their type with every web request, such as Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A.
Significance of Default Gateways
Typically, your default gateway is an automatically assigned address through DHCP, like 10.19.67.157 (often ending in .1 or .254 based on scope size), and it serves as the routing point for all your computer’s outgoing traffic. For IPv6, detailed instructions can be found in how-to-fix-ipv6-connectivity/, and you can verify this on Mac or Linux 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 10.19.67.157 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 fe80:3b3a:d2da:d30a:8dd5%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): {167.204.76.216, 83.170.112.163}
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 8f:96:a4:a8:7f:b0
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 f3:50:b1:b3:32:40
}
Diagnose and Resolve Issues with Wired and Wireless Connections
When sending data to your router, you may utilize either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Effective Troubleshooting Methods for Apple macOS / OSX Users
Regardless of your current OSX/macOS version, whether it’s 10.12.1, 11.3.9, or 12.1.3, there exists a variety of tools for troubleshooting. However, these manual actions and scripts fail to provide a set of correlated values over time, leading to the significance of automated remote troubleshooting, especially for teams engaging in remote work and Work From Anywhere (WFA).
Utilize the Built-in Scripts for Assistance
A valuable tool on OSX/macOS is the sudo wdutil info, which provides a comprehensive dump of current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool offers a more comprehensive option for generating various logs, although most of it is only relevant in relation to wireless, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will produce logs in /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, albeit with minimal interaction, you can execute sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. Not running it in the background should open Finder in the correct location, and you can navigate to /var/tmp or use Finder with Cmd+Shift+G to point Finder to the path. Keep in mind the file sizes, which will be around 300MB or slightly more.
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