Test Apple Connectivity
Understanding Internet Address Allocation
When using the Internet, you are assigned a unique Public IPv4 address, such as 98.246.88.232, or an IPv6 address, like 2000:45ad:5695:40ae:86f0:11aa:79f5:cc7. You can verify your address at https://test-ipv6.com/. Conveying these addresses, as well as MAC addresses like 94:4e:4c:be:76:73, to individuals who are not well-versed in technology can be challenging and error-prone. Moreover, it does not provide any historical data, which is especially valuable for identifying past issues.
Navigating the World Wide Web
In order to access a website, such as https://von.info, you must first contact a DNS server to convert the host portion (von) along with the Top Level Domain (info) of the URL into an IP address, like 62.116.233.76. When making web requests, your computer and browser both send specific information, such as Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285.
Understanding the Significance of Default Gateways
Your default gateway is typically automatically configured through DHCP and is assigned an address, such as 172.30.17.106 (usually ending in .1 or .254 depending on the scope size). This is where your computer directs all of its traffic to be routed onwards. For IPv6, detailed instructions can be found at how-to-fix-ipv6-connectivity/, but on Mac or Linux, you can check 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 172.30.17.106 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 fe80:59d5:ef96:3c25:9f00%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): {42.54.102.154, 82.87.172.162}
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 94:4e:4c:be:76:73
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 56:48:6f:48:e2:37
}
Resolve Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you may be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Solutions for Apple macOS / OSX
No matter which version of OSX or macOS you have, whether it’s 10.14.5, 11.2.9, or 12.2.7, there are various troubleshooting tools available. However, these manual actions and scripts don’t provide a comprehensive set of correlated values over time. This is where automated remote troubleshooting becomes valuable, particularly for teams that support remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
A valuable tool on OSX/macOS is sudo wdutil info, which provides a dump of the current wireless settings to 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 much of it is only related to wireless settings at a specific point in time, similar to wdutil.
To run it in the background and write logs to /var/tmp/<blah>.tar.gz, you can use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can use the command sudo /usr/bin/sysdiagnose, which 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 using Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB.
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