Test Mac Connectivity
Functioning of Internet Addressing
When using the Internet, individuals are assigned a Public IPv4 address like 76.121.69.82 or an IPv6 address like 2000:d8f0:5fe6:cf8f:57de:e17d:9d18:2355. Verification of these addresses can be done through https://test-ipv6.com/. However, for those not well-versed in technology, communicating these addresses or MAC addresses like 8b:06:07:57:e6:88 can be prone to errors and quickly become complicated. Additionally, this method does not provide any historical data, especially regarding previous issues that have arisen.
Navigating the Internet
In order to access a webpage such as https://heathcote-koss.org, the initial step involves accessing a DNS server to convert the host portion (heathcote-koss) combined with the Top Level Domain (org) of the URL into an IP address such as 130.36.97.172. Each web request from your computer and browser includes its type, 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 automatically configured address via DHCP. Usually, a default gateway such as 192.168.12.11 is assigned (though they typically end in .1 or .254 depending on the scope size), and this is where your computer sends all its traffic to be routed onwards. For IPv6, detailed instructions on how to fix connectivity can be found at how-to-fix-ipv6-connectivity/. On Mac or Linux, the status can be checked 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 192.168.12.11 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 bb95:f8ec:e291:ef:1d9d:2080:9b21:1816%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): {143.45.128.86, 157.194.53.5}
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 8b:06:07:57:e6:88
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 1c:c6:ef:32:4e:68
}
Fixing Connectivity Issues for Wired or Wireless Networks
When it comes to transmitting data to your router at the physical and data layer, you might be utilizing either a wired or a wireless (Wi-Fi) medium.
Troubleshooting on Apple macOS / OSX Systems
Regardless of whether you are working on OSX/macOS version 10.13.5, 11.6.6, or 12.3.7, there are various tools available for troubleshooting. 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 are embracing remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
A very useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings to the CLI and can also be configured to generate specific logs for troubleshooting. Another comprehensive tool is the sysdiagnose tool, which can generate a wide range of logs related to wireless issues, although they are mostly point-in-time logs similar to the ones generated by wdutil.
You can run sudo nohup /usr/bin/sysdiagnose -u & in the background, and it will write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively, you can run sudo /usr/bin/sysdiagnose (although there is not much interaction) and it will give a privacy warning. If not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to locate the path. Just be mindful of the file sizes, which can be around 300MB more or less.
Possibly Helpful Videos
P.S. Tips For Remote Network and Client Support
Digital work requires reliable connectivity. Whether for low latency or regular data streams, Wi-Fi, DNS, and network issues cause teams to lose time and productivity. Even worse is when support teams waste time trying to recreate and isolate issues! See how PanSift saves time, money, and frustration on all sides with instant remote troubleshooting 🏠🏝🛰.
