How Do You Support Mac IP Settings
Understanding Internet Addressing
When it comes to the Internet, you are assigned a Public IPv4 or IPv6 address for communication. These addresses, such as 55.117.48.40 or 2000:ae6f:8324:3825:4b2e:85ff:d09c:60b3, can be verified using https://test-ipv6.com/. Communicating these addresses, along with MAC addresses like 54:49:9c:c1:d9:09, can be challenging and error-prone for non-technical individuals, adding complexity to the process, with no access to historical data.
Navigating the World Wide Web
The process of accessing a website, such as https://hettinger.com, involves reaching out to a DNS server to convert the URL’s Top Level Domain (com) and host portion (hettinger) into an IP address like 29.204.203.2. Your computer and browser send web request types, such as Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16.
Significance of Default Gateways
The default gateway, usually obtained through DHCP auto-configuration, is an essential address, typically ending in .1 or .254 depending on the scope size. This is where your computer directs all its traffic for further routing. For IPv6, detailed information can be found in how-to-fix-ipv6-connectivity/, and for Mac or Linux systems, it is possible to verify 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 192.168.161.187 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 fe80:5c2d:d621:cc91:c42%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): {89.106.43.246, 106.11.149.162}
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 54:49:9c:c1:d9:09
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 ca:a6:4e:fb:7b:a7
}
Resolving Issues with Wired and Wireless Connections
When transmitting data to your router, you may encounter complications at the physical and data layer, whether you are using a wired or wireless (Wi-Fi) medium.
Effective Solutions for Apple macOS / OSX Users
Regardless of the version of OSX/macOS you are running, whether it be 10.12.3, 11.6.7, or 12.1.2, there are various troubleshooting tools available. However, these manual actions and scripts fail to provide a set of interconnected values over time. This is where automated remote troubleshooting becomes highly beneficial, particularly for teams that have embraced remote work and Work From Anywhere (WFA).
Utilizing Pre-Installed Scripts for Assistance
One particularly useful tool on OSX/macOS is the sudo wdutil info command, which displays current wireless-related settings in the command line interface and can also be configured to generate specific troubleshooting logs. Moreover, the sysdiagnose tool can be utilized to produce a wide range of logs, though many of the logs are only relevant to the wireless network at a specific point in time, similar to wdutil.
To run it in the background and generate logs in /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively (although there is minimal interaction), you can use the command sudo /usr/bin/sysdiagnose and it will prompt a privacy warning. When not run in the background, Finder should open in the correct location, or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to point to the path. However, be cautious of the file sizes, which are roughly around 300MB.
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