How Do You Check OSX Internet Connection
Demystifying IP Addressing
When using the Internet, you are assigned a unique public IP address, such as 178.85.14.254 for IPv4 or 2000:a150:e491:fdbd:4fce:d3c2:1a8d:da6f for IPv6. You can verify this information by visiting https://test-ipv6.com/. Nonetheless, conveying these addresses, and even MAC addresses like b0:83:88:59:b0:6f, to those not well-versed in technology can be prone to errors and quickly become complicated. Moreover, this data does not provide any historical context, particularly when resolving past issues.
Navigating the World Wide Web
Accessing a web page such as https://runolfsdottir.co requires the use of a DNS server to convert the host segment (runolfsdottir) combined with the Top Level Domain (co) of the URL into an IP address like 157.165.36.139. When making web requests, your computer and browser also transmit their type, for example: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
Understanding the Significance of Default Gateways
Your default gateway is usually assigned automatically through DHCP. It typically takes the form of an address like 172.17.122.221 (although they usually end in .1 or .254 depending on the scope size), and serves as the location where your computer forwards all of its traffic for routing. For a comprehensive exploration of IPv6, you can refer to our article on how-to-fix-ipv6-connectivity/, or verify on Mac or Linux with:
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 172.17.122.221 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:dc5e:2d14:4128:730%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): {28.196.194.229, 59.14.190.218}
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 b0:83:88:59:b0:6f
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 15:fd:bd:07:8b:13
}
Fixing Connectivity Issues for Wired and Wireless Networks
When it comes to transmitting data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Solutions for Apple macOS / OSX Users
Regardless of whether you are using OSX/macOS versions like 10.14.8, 11.6.4, or 12.2.8, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time, making automated remote troubleshooting essential for teams that have embraced remote work and Work From Anywhere (WFA).
Effective Built-in Tools for Troubleshooting
On OSX/macOS, sudo wdutil info is a useful tool that generates current wireless related settings dump to the CLI and can also be configured to generate specific troubleshooting logs. Furthermore, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only relevant to wireless at specific points in time, similar to wdutil.
To run sysdiagnose in the background and generate logs at /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. Alternatively, for an interactive run, use sudo /usr/bin/sysdiagnose (which will display a privacy warning). When not running in the background, it should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. However, be mindful of file sizes, which can be around 300MB.
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