How Can I Test Apple Connectivity
Understanding Internet Addressing
When using the Internet, you are assigned either a Public IPv4 address, such as 37.185.20.188, or an IPv6 address, like 2000:bb33:a166:a81c:efd:be54:779f:97c1. You can verify this through the https://test-ipv6.com/ website. However, for those not familiar with technical jargon, communicating these addresses - or even MAC addresses like 1e:73:89:e1:9a:a7 - can be confusing and prone to errors. Moreover, it fails to provide any historical data, particularly from previous incidents.
Navigating the Online World
When accessing a website such as https://fritsch-prohaska.co, you begin by contacting a DNS server to translate the host portion (fritsch-prohaska) along with the Top Level Domain (co) of the URL to an IP address, such as 181.44.246.26. Every web request from your computer and browser includes its type, for instance:
Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
Understanding the Role of Default Gateways
The default gateway is typically an automatically configured address via DHCP. A default gateway like 192.0.0.105 (usually ending in .1 or .254, depending on the scope size) is where your computer directs all of its traffic to be routed onward. For troubleshooting IPv6 connectivity on Mac or Linux, you can refer to our extensive guide 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 192.0.0.105 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 fe80:3c44:2b4d:7052:5c64%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): {112.229.63.5, 216.218.225.93}
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 1e:73:89:e1:9a:a7
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 9b:f9:bb:05:32:f0
}
Fixing Connectivity Issues: Wired vs. Wireless
When it comes to transmitting data to your router, you might be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting on Apple macOS / OSX
Regardless of which version of OSX/macOS you are using - whether it’s 10.15.5, 11.2.8, or 12.0.4, there are various tools available for troubleshooting. However, these tools and scripts don’t provide a set of correlated values over time. This is where automated remote troubleshooting can be especially beneficial, particularly for teams that are embracing remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
An incredibly useful tool on OSX/macOS is sudo wdutil info, which provides a dump of the current wireless settings in the CLI and can be configured to generate specific troubleshooting logs. In addition, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only related to wireless settings at a specific point in time, 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 run sudo /usr/bin/sysdiagnose and it will give a privacy warning. When 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 point Finder to the path. Just be aware that the file sizes are around 300MB more or less.
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