Test MacOS Internet
Understanding the Function of Internet Addresses
When using the Internet, you may be assigned a Public IPv4 address such as 100.31.114.23 or an IPv6 address like 2000:2c94:569c:2066:9da0:d776:7c4d:7216. You can verify this by visiting https://test-ipv6.com/. However, conveying these addresses, or even referencing MAC addresses like 94:7b:c1:bc:56:0a, can be complex and error-prone, especially for those who are not technologically inclined. Furthermore, this method does not provide any historical information, particularly pertaining to past issues.
Navigating the World Wide Web
When attempting to access a website such as https://sanford-weissnat.name, you first connect to a DNS server to convert the host section (sanford-weissnat), in combination with the Top Level Domain (name) of the URL, into an IP address like 119.166.87.197. Your computer and browser actually transmits its type with each web request, for example:
Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
The Significance of Default Gateways
Your default gateway is typically a dynamically configured address through DHCP. You will receive a default gateway such as 192.168.189.68 (although they generally end in .1 or .254, depending on the scope size), and this is where your computer directs all its traffic to be routed onward. For IPv6, refer to our comprehensive guide on how-to-fix-ipv6-connectivity/. However, on Mac or Linux, you 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 192.168.189.68 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 fe80:4523:2f43:f740:5e13%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): {165.74.26.136, 6.222.5.18}
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 94:7b:c1:bc:56:0a
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 9d:51:4d:88:8d:7e
}
Resolving Connectivity Issues for Wired and Wireless Networks
When it comes to the physical and data layer, you might be utilizing either a wired or wireless (Wi-Fi) medium to transmit data to your router.
Troubleshooting on Apple macOS / OSX
Regardless of which version of OSX/macOS you are running - whether it’s 10.13.9, 11.2.4, or 12.3.4 - there are various tools available for resolving connectivity issues. However, these manual actions and scripts do not provide a comprehensive set of correlated values over time. This is where automated remote troubleshooting becomes essential, particularly for teams that adopt remote work and Work From Anywhere (WFA) practices.
Utilizing Built-in Scripts for Assistance
One useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI, and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to produce a wide range of logs, although many of them are only point-in-time data related to wireless, similar to wdutil.
To run sysdiagnose in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose (although there is minimal interaction), 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 Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB.
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