How To Test Apple Internet Connection
An Overview of Internet Addressing
When using the Internet, you may be assigned a public IPv4 address such as 253.239.29.48 or an IPv6 address like 2000:1fa3:9d8d:1b68:bbea:2cd0:766d:9f7b. You can verify this information by visiting https://test-ipv6.com/. However, explaining and working with these addresses, and even specific MAC addresses like 1c:ce:5f:d5:1d:cb, can be error-prone and confusing for those who are not familiar with technical details. Moreover, this method does not provide any historical data, particularly regarding previous issues.
Navigating the Internet
When attempting to access a website such as https://harris-howe.com, the first step involves using a DNS server to convert the host portion (harris-howe) along with the top-level domain (com) of the URL into an IP address, such as 8.142.121.86. Moreover, every web request made by your computer and browser includes its type, as shown by: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
Understanding the Significance of Default Gateways
Typically, your default gateway is an address that is automatically configured through DHCP. The default gateway, such as 10.127.25.147 (which usually ends in .1 or .254 depending on the scope size), is where your computer directs all its traffic to be further routed. If you are interested in how to manage this process for IPv6, you can refer to our in-depth discussion on how-to-fix-ipv6-connectivity/. Additionally, you can verify this information on Mac or Linux by 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 10.127.25.147 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:c08f:dc6d:52c5:49df%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): {226.195.130.84, 127.111.33.77}
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 1c:ce:5f:d5:1d:cb
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 5a:6a:23:2b:c5:1f
}
Resolving Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you might be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Guide for Apple macOS / OSX
Regardless of the version of your OSX/macOS - whether it’s 10.12.1, 11.3.8, or 12.3.1, there are various troubleshooting tools available. However, these manual methods and scripts lack the ability to provide a set of correlated values over time. This is where automated remote troubleshooting becomes highly valuable, especially for teams that are transitioning to remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
An extremely useful tool within OSX/macOS is sudo wdutil info, which provides a dump of the current wireless settings to the CLI and can also be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool offers a more comprehensive option for generating a wide range of logs, although much of the information is only relevant at a specific point in time, similar to wdutil.
By running sudo nohup /usr/bin/sysdiagnose -u & in the background, logs will be written to /var/tmp/<blah>.tar.gz for your convenience. If you prefer to run it interactively (even though there isn’t much interaction), you can use the commandsudo /usr/bin/sysdiagnose, which will prompt a privacy warning. When not run in the background, it will open Finder in the correct location, or you can navigate to the /var/tmp directory using Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB.
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