How Can I Fix Mac Internet
Understanding the Operation of Internet Addresses
When connected to the internet, you will be assigned a unique Public IPv4 address, for example 90.106.200.46, or an IPv6 address like 2000:a2d6:ac01:58cb:23dc:f56e:8ec5:f1b1. You can verify this assignment by visiting https://test-ipv6.com/. However, conveying these addresses to those not well-versed in technology, and even referencing MAC addresses such as f3:f5:aa:e4:71:fa, can lead to errors and complications. It is also notably lacking in historical data, especially pertaining to past issues.
Navigating the Internet
When attempting to access a website like https://corwin.io, the first step is to contact a DNS server to convert the host section (corwin) combined with the Top Level Domain (io) of the URL to an IP address, such as 79.166.184.204. Notably, your computer and browser includes information about its type in each web request, for example:
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
The default gateway is typically an address that is automatically configured through DHCP. An example of a default gateway is 192.168.123.116 (although they generally conclude with .1 or .254 depending on the scope size), which is the destination for all outgoing traffic from your computer. For guidance on configuring IPv6, a comprehensive explanation is provided in the post how-to-fix-ipv6-connectivity/, but the procedure can be verified on Mac or Linux by using the following command:
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 192.168.123.116 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 fe80:1e3c:5727:8e51:6b95%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): {191.146.255.32, 214.5.9.77}
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 f3:f5:aa:e4:71:fa
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 c1:a1:9e:3b:7c:26
}
Resolving Issues with Wired and Wireless Connections
When it comes to transmitting data, the choice between wired or wireless (Wi-Fi) at the physical and data layer can impact your connectivity to the router.
Troubleshooting Tips for Apple macOS / OSX
Irrespective of whether you are using OSX/macOS version 10.14.1, 11.1.2, or 12.3.3, there are various methods and tools available for troubleshooting connectivity issues. However, these methods and scripts do not provide a continuous stream of correlated data over time. This is where automated remote troubleshooting becomes crucial, especially for teams that operate in a remote work or Work From Anywhere (WFA) setup.
Utilizing Pre-installed Scripts for Assistance
A useful built-in tool for OSX/macOS is the sudo wdutil info command, which provides a detailed dump of current wireless settings in the CLI. It can also be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool offers a more comprehensive option for generating a wide range of logs related to wireless connectivity, even though most of the information is only relevant at a specific point in time, similar to wdutil.
To run sysdiagnose in the background and save logs to /var/tmp/<blah>.tar.gz, you can use the command sudo nohup /usr/bin/sysdiagnose -u &. Alternatively, to run it interactively, you can use the command sudo /usr/bin/sysdiagnose, which will provide a privacy warning. When not run in the background, it should open Finder in the correct location, allowing you to access the logs or use the Finder with Cmd+Shift+G to navigate to the specific path. However, be mindful of the file sizes, which can be around 300MB.
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