How Do You Support OSX Internet
Understanding the Function of Internet Protocol Addresses
When using the internet, you may be assigned a Public IPv4 address such as 24.63.61.2 or an IPv6 address like 2000:2798:53ce:9766:5a48:1457:4f3c:498. The verification of these addresses can be done through https://test-ipv6.com/. However, conveying these addresses to individuals unfamiliar with technology, or even referencing MAC addresses like f5:b7:bb:fe:38:66, can be prone to errors and can become complex rather quickly. Moreover, this method does not provide any historical data, especially when dealing with past issues.
Navigating the World Wide Web
In order to access a web page such as https://adams.name, you first connect to a DNS server to convert the host part (adams) in combination with the URL’s Top Level Domain (name) to an IP address like 105.54.141.41. Interestingly, whenever your computer and browser make web requests, they send their type along with it, for example: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A.
Significance of Default Gateways
The default gateway is usually an automatically configured address obtained via DHCP. A typical default gateway might be something like 192.0.0.208 (although they generally end in .1 or .254, depending on the scope size), and this is where your computer directs all its traffic to be further routed. For IPv6, there is a detailed analysis available at how-to-fix-ipv6-connectivity/, but it can also 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 192.0.0.208 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 fe80:889b:2912:af2a:416a%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): {246.5.190.97, 221.58.184.104}
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 f5:b7:bb:fe:38:66
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 93:77:16:d6:9e:38
}
Resolution of Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you could be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX Users
Regardless of the version of OSX/macOS you are running, whether it’s 10.14.2, 11.0.7, or 12.1.6, there are various troubleshooting tools available. However, these tools do not provide a series of correlated values over time, which is where automated remote troubleshooting proves to be beneficial, especially for remote work and Work From Anywhere (WFA) scenarios.
Useful Built-in Scripts
One of the valuable tools on OSX/macOS is the sudo wdutil info command, which displays current wireless settings in the CLI and can be configured to generate specific troubleshooting logs. Moreover, the sysdiagnose tool can be used to generate a wide range of logs, although many of them are only related to wireless settings and are not continuous like wdutil.
To run sysdiagnose in the background and write logs to /var/tmp/<blah>.tar.gz, you can execute the command: sudo nohup /usr/bin/sysdiagnose -u &. Alternatively, if you prefer to run it interactively, you can use the command: sudo /usr/bin/sysdiagnose, but be mindful of the large file sizes of around 300MB.
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