How To Test Mac Internet
The Functionality of Internet Addressing
When using the internet, you are assigned a unique IP address, such as 40.220.109.206 for IPv4 or 2000:1617:7ced:f45e:4693:4118:4b54:afe7 for IPv6. The validation of this can be done at https://test-ipv6.com/, but communicating or referencing these addresses can be complex and prone to errors, especially for those unfamiliar with technical terminology. Furthermore, this method lacks any historical data, particularly when issues have occurred in the past.
Navigating the Internet
Accessing a website, such as https://volkman-pagac.com, involves connecting to a DNS server to translate the host (volkman-pagac) and the Top Level Domain (com) of the URL into an IP address, like 34.141.67.41. Each web request sent from your computer and browser contains its type, such as: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A
The Significance of Default Gateways
The default gateway is an automatically assigned address through DHCP, typically ending in .1 or .254, depending on the scope size, like 192.168.221.59. This is the point to which your computer sends all its traffic to be further routed. For IPv6, detailed instructions on checking this on Mac or Linux can be found at: how-to-fix-ipv6-connectivity/
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 192.168.221.59 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 fe80:8b17:1189:a300:c189%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): {219.4.99.79, 137.150.112.81}
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 d1:c9:e3:14:e8:d8
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 22:a5:d6:eb:30:3f
}
Diagnose and Solve Connectivity Issues, Whether Wired or Wireless
When it comes to transmitting data to your router, you might be using a wired or wireless (Wi-Fi) medium at the physical and data layers.
Troubleshooting Tips for Apple’s macOS / OSX Platform
No matter which version of OSX/macOS you’re running, whether it’s 10.15.5, 11.1.9, or 12.2.9, there are various tools available for troubleshooting. However, manual actions and scripts fail to provide a series of correlated values over time. This is where automated remote troubleshooting proves to be beneficial, particularly for teams that have embraced remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
One particularly useful tool on OSX/macOS is sudo wdutil info, which dumps the current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be utilized to generate a wide range of logs, although much of it is only relevant to wireless at a specific point in time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & will execute sysdiagnose in the background and write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively (despite minimal interaction), you can run 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, or you can navigate to /var/tmp by using Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB.
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