How Can I Test OSX Internet
Understanding Internet Addressing
When using the Internet, your device may have a Public IPv4 address similar to 8.48.98.3 or an IPv6 address like 2000:1437:3c9:f0ba:bd64:a2f:71f:6731. You can verify this information by visiting https://test-ipv6.com/. However, for individuals who are not familiar with technical details, attempting to communicate these addresses, or even mentioning MAC addresses like eb:6f:cb:64:da:e7, can lead to errors and complexity. Furthermore, this method does not provide any historical data, particularly when there were previous issues.
Navigating the World Wide Web
Accessing a website such as https://cartwright.org involves initially reaching out to a DNS server to convert the host portion (cartwright) combined with the Top Level Domain (org) of the URL into an IP address, such as 229.21.69.154. When making web requests, your computer and browser actually send their types, which can be seen as follows: Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
Understanding the Significance of Default Gateways
Typically, your default gateway is an automatically allocated address through DHCP. You are assigned a default gateway such as 192.168.72.24 (although they often end in .1 or .254 depending on the scope size), and this is where your computer sends all its traffic to be routed onwards. To delve deeper into IPv6 connectivity issues, there is an in-depth guide available at how-to-fix-ipv6-connectivity/. On Mac or Linux, you can verify this information with 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 192.168.72.24 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 fe80:5cf1:1f51:1e1e:fe69%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): {8.238.48.98, 99.97.49.133}
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 eb:6f:cb:64:da:e7
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 cc:c1:d5:1c:b7:5b
}
Solve Issues with your Wired or Wireless Connection
When it comes to transmitting 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 version 10.14.5, 11.6.5, or 12.2.9, there are various methods for troubleshooting network issues. However, these manual methods and scripts do not provide a set of interconnected values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that adopt remote work and Work From Anywhere (WFA) practices.
Useful Built-in Scripts
One useful tool for troubleshooting on OSX/macOS is sudo wdutil info, which provides a dump of the current wireless settings to the Command Line Interface (CLI), and can be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although many are only relevant at a specific point in time, similar to wdutil.
sudo nohup /usr/bin/sysdiagnose -u & runs the tool in the background and writes logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively (even though there isn’t much interaction), you can usesudo /usr/bin/sysdiagnose, which will prompt a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to locate the path. Keep in mind that the file sizes are approximately 300MB.
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