How Do You Test MacOS Internet Connection
Understanding Internet Addressing
When browsing the Internet, you can be assigned a Public IPv4 address such as 145.21.203.5, or an IPv6 address like 2000:81ec:a641:40e8:f293:e189:ec30:ec8f. You can verify this information by visiting https://test-ipv6.com/. However, for those who are not tech-savvy, communicating these addresses and MAC addresses like 07:97:82:a4:90:6d can be error-prone and overwhelming, without providing historical data.
Navigating the Web
When accessing a web page like https://pollich-toy.name, you first connect to a DNS server that translates the host portion (pollich-toy) along with the Top Level Domain (name) of the URL to an IP address such as 7.150.242.220. Your computer and browser send their type with every web request, for example: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko.
The Significance of Default Gateways
Your default gateway is typically an automatically assigned address via DHCP, such as 172.25.78.186 (usually ending in .1 or .254 depending on the scope size). This is where your computer sends all its traffic to be routed onwards. For IPv6, there is an in-depth guide on how-to-fix-ipv6-connectivity/, and can be checked on Mac or Linux 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 172.25.78.186 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 fe80:29c2:e115:e3e1:5a0b%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): {210.168.201.12, 29.31.143.31}
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 07:97:82:a4:90:6d
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 27:d8:9e:56:f4:21
}
Resolving Connectivity Issues for Wired and Wireless Networks
When it comes to transmitting data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Techniques for Apple macOS / OSX Users
Regardless of whether you are running 10.15.7, 11.1.6, or 12.2.8, there are a variety of troubleshooting tools available for OSX/macOS. However, manually performing these actions and scripts does not provide a set of correlated values over time. This is where automated remote troubleshooting becomes essential, especially for teams that are adopting remote work and Work From Anywhere (WFA) policies.
Leveraging Pre-installed Scripts for Assistance
A useful tool on OSX/macOS is the sudo wdutil info, which provides a detailed dump of current wireless settings to the command-line interface (CLI). It can also be configured to generate specific logs for troubleshooting purposes. Furthermore, the sysdiagnose tool can generate a wide range of logs, although much of it pertains to wireless settings and is only relevant for a specific point in time, similar to wdutil.
To run it in the background and write logs to /var/tmp/<blah>.tar.gz, you can use the command sudo nohup /usr/bin/sysdiagnose -u &. For an interactive run, you can execute sudo /usr/bin/sysdiagnose and it will display a privacy warning. If not run in the background, it should open Finder in the correct location, from where you can navigate to /var/tmp or use Finder with Cmd+Shift+G to point Finder to the path. However, be cautious of the file sizes, which are approximately 300MB.
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