How Do You Understand Apple Internet Connection
Understanding Internet Addressing
When using the Internet, individuals may receive a Public IPv4 address, such as 96.231.230.152, or an IPv6 address, for example 2000:28fd:3750:ad3:9ae0:b847:11ac:cb37. Verification of this information can be done at https://test-ipv6.com/. However, explaining and communicating these addresses, along with MAC addresses like 2b:36:bc:8c:11:f1, can be prone to errors and becomes complex for non-technical users. There is also a lack of historical data, which limits the understanding of past issues.
Navigating the World Wide Web
To visit a website, such as https://hamill.org, the process involves accessing a DNS server to translate the URL’s host portion (hamill) and Top Level Domain (org) into an IP address, such as 206.203.95.110. Interestingly, each web request from the computer and browser also includes its type, demonstrated by Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16.
Significance of Default Gateways
The default gateway is typically an automatically configured address assigned through DHCP. This default gateway, often ending in .1 or .254 depending on the scope size, is where all of the computer’s traffic is sent for further routing. For IPv6 related information, a detailed discussion can be found at how-to-fix-ipv6-connectivity/. On Mac or Linux systems, this information can be verified using specific commands.
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 172.27.23.105 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 fe80:284d:193a:e3cb:299d%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): {145.204.250.20, 187.189.216.138}
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 2b:36:bc:8c:11:f1
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 5f:1d:70:eb:6d:87
}
Resolving Issues with Wired or Wireless Connections
When it comes to sending data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Strategies for Addressing Problems on Apple macOS / OSX
No matter which version of OSX/macOS you are currently running, whether it’s 10.13.6, 11.0.1, or 12.2.4, there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a set of interconnected values over time. This is where automated remote troubleshooting becomes particularly valuable, especially for teams that are embracing remote work and Work From Anywhere (WFA).
Pre-installed Scripts That Offer Assistance
One extremely useful tool on OSX/macOS is the sudo wdutil info, which provides a dump of the current wireless settings in the CLI and can also generate specific logs for troubleshooting. Furthermore, the sysdiagnose tool can be used to produce a wide range of logs, although many are only relevant 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. Alternatively, if you prefer to run it interactively, you can execute sudo /usr/bin/sysdiagnose, which will also display a privacy warning. When not run in the background, it should open Finder in the correct location, allowing you to navigate to /var/tmp or use Finder with Cmd+Shift+G. However, be mindful of the file sizes, which are approximately 300MB.
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