How Can I Test MacOS Internet Connection
Understanding Internet Address Assignment
When using the Internet, you are assigned a Public IPv4 address or an IPv6 address, which can be verified at https://test-ipv6.com/. However, for those who are not well-versed in technology, communicating and handling these addresses, including MAC addresses, can be prone to errors and become complex. Moreover, historical data is not readily available, especially when troubleshooting past issues.
Navigating the World Wide Web
Accessing a webpage, such as https://bergnaum.org, involves initially contacting a DNS server to translate the host and Top Level Domain of the URL into an IP address. In addition, the type of computer and browser is communicated with each web request, for example: Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)
Significance of Default Gateways
The default gateway is typically an address that is automatically configured via DHCP, such as 10.181.192.253, where all the computer’s traffic is routed. For IPv6, you can delve deeper into how-to-fix-ipv6-connectivity/ or check for it on Mac or Linux using the following commands:
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 10.181.192.253 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:aa2f:bd31:fb99:f6ca%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): {226.188.19.222, 178.131.243.151}
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 ea:e1:e5:29:4a:e0
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 e2:75:59:e6:6d:48
}
Resolve Issues with Wired and Wireless Connections
Whether you are using a wired or wireless (Wi-Fi) medium to transmit data to your router, troubleshooting at the physical and data layer is essential.
Tips for Troubleshooting on Apple macOS / OSX
No matter the version of OSX/macOS you are currently using, be it 10.11.6, 11.6.7, or 12.3.9, there are various tools available for resolving issues. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that have embraced remote work and the Work From Anywhere (WFA) approach.
Use of In-Built Scripts for Assistance
One useful tool on OSX/macOS is the sudo wdutil info which provides a dump to the Command Line Interface (CLI) of current wireless settings, 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, although much of it is only relevant to wireless settings and is not a continuous source of information like wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs at /var/tmp/<blah>.tar.gz. If you prefer to run it interactively (though there is minimal interaction), you can use sudo /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 using Cmd+Shift+G in Finder. Keep in mind that the file sizes are approximately 300MB.
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