Support MacOS Connectivity
Understanding Internet Protocol Addressing
In the world of the Internet, you are assigned an IPv4 address, such as 16.246.178.176, or an IPv6 address, like 2000:5133:a306:7175:8d5c:b59a:656a:4a8e. You can verify these addresses by visiting https://test-ipv6.com/. However, conveying these addresses to individuals who are not well-versed in technological matters can be prone to errors and become complex. Furthermore, this method provides no historical data, especially during past issues.
Navigating the World Wide Web
When attempting to reach a webpage, such as https://ward.info, you must first access a DNS server to translate the host (ward) and the Top Level Domain (info) of the URL into an IP address, such as 233.173.144.130. Every web request from your computer and browser includes information about its type, such as 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 address that is configured automatically via DHCP. It could be a default gateway like 10.218.109.198 (usually ending in .1 or .254, depending on the scope size) where your computer directs all its traffic to be routed. For IPv6, a detailed guide on how-to-fix-ipv6-connectivity/ is available, and you can check this 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 10.218.109.198 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 fe80:5ffc:830d:4d78:6980%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): {138.223.86.1, 218.200.140.49}
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 a8:6f:5f:35:69:89
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 87:81:52:3e:20:a3
}
Resolving Issues with Wired and Wireless Connections
When it comes to transferring data to your router, you have the option of using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX Users
No matter which version of OSX/macOS you are currently using - whether it’s 10.12.3, 11.0.8, or 12.2.7 - there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes crucial, particularly for teams that have adopted remote work and the Work From Anywhere (WFA) approach.
Useful Built-in Scripts
One of the valuable tools 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. In addition, the sysdiagnose tool can generate a wide range of logs, although most of them are only relevant to a specific point in time in relation to wireless, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose, 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 Cmd+Shift+G in Finder. Keep in mind that the file sizes are approximately 300MB.
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