How To Check Apple Internet Connection
The Functioning of Internet Addressing
When using the Internet, you are assigned a Public IPv4 address such as 210.178.96.62 or an IPv6 address such as 2000:79c2:a1cc:f810:b628:9a9e:7131:1382. This information can be verified by visiting https://test-ipv6.com/. However, explaining or communicating these addresses, or even specifying MAC addresses like db:5e:38:cd:57:50, can be error-prone and complex, especially for those who are not tech-savvy. Moreover, this method does not provide any historical data, particularly from past issues.
Navigating the Internet
In order to visit a website such as https://steuber-orn.io, the first step is to access a DNS server that translates the host portion (steuber-orn) combined with the Top Level Domain (io) of the URL into an IP address, like 189.71.18.215. Additionally, your computer and browser include its type in all web requests, 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
The Significance of Default Gateways
A default gateway is typically an automatically configured address via DHCP. It is similar to getting a default gateway like 10.204.216.148 (usually ending in .1 or .254 based on the scope size), and serves as the point where your computer sends all its traffic to be routed onward. For IPv6, detailed instructions can be found in the post how-to-fix-ipv6-connectivity/, and can 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 10.204.216.148 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 fe80:59e4:2671:6e98:246%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): {179.183.179.3, 246.244.96.80}
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 db:5e:38:cd:57:50
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 b8:90:01:93:02:48
}
Resolve Issues with Wired and Wireless Connections
When it comes to transferring data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Tips for Apple macOS / OSX Troubleshooting
Regardless of whether you are on OSX/macOS versions like 10.13.8, 11.6.8, or 12.0.5, 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 invaluable, especially for teams that are transitioning to remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
On OSX/macOS, the sudo wdutil info tool provides a dump to the CLI of current wireless-related settings and can be configured to generate specific troubleshooting logs. Additionally, the sysdiagnose tool offers a more comprehensive option for generating a variety 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 & in the background will write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose with a privacy warning. When 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 files. Be cautious of the file sizes, which are approximately 300MB.
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