How Can I Check Apple IP Settings
Understanding the Functioning of Internet Addressing
When using the Internet, your device may be assigned a Public IPv4 address such as 201.181.29.181 or an IPv6 address like 2000:3d9b:ee09:8cde:6b82:c65d:285e:6775. These addresses can be verified at https://test-ipv6.com/. However, for individuals who are not familiar with technical aspects, conveying these addresses, or even referencing MAC addresses like d3:b5:02:ef:7c:e5, can lead to errors and complexity. Moreover, it does not provide any historical data, especially relating to previous issues.
Navigating through the World Wide Web
When attempting to reach a website, such as https://price.info, your initial interaction involves accessing a DNS server to convert the host part (price) combined with the Top Level Domain (info) of the URL into an IP address like 39.39.187.3. Furthermore, your computer and browser communicate their type with all web requests, for instance: Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
Significance of Default Gateways
The default gateway is usually an address that is automatically configured through DHCP. It is assigned as a default gateway, such as 192.0.0.59 (though they typically end in .1 or .254 based on the scope size), and serves as the destination for all your computer’s traffic to be routed onwards. For IPv6, a comprehensive guide is available in the article how-to-fix-ipv6-connectivity/, and it can be checked on Mac or Linux using the following command:
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 192.0.0.59 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 fe80:95a:ee06:1602:d737%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): {46.202.23.191, 234.178.196.89}
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 d3:b5:02:ef:7c:e5
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 83:bd:ed:35:9e:f8
}
Fixing Connectivity Issues for Wired and Wireless Networks
Whether you’re using a wired or wireless (Wi-Fi) connection at the physical and data layer to transmit data to your router, troubleshooting connectivity issues is essential.
Tips for Resolving Problems on Apple macOS / OSX
Regardless of whether you are running OSX/macOS version 10.14.6, 11.6.8, or 12.3.9, there are various troubleshooting tools available. However, these manual methods and scripts do not provide a set of correlated values over time, making automated remote troubleshooting particularly valuable for teams embracing remote work and Work From Anywhere (WFA).
Utilizing Pre-installed Scripts for Assistance
One extremely beneficial tool on OSX/macOS is the sudo wdutil info, which provides a dump of current wireless settings to the CLI and can also be set up to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to produce a wide range of logs, although much of it is only relevant to wireless at a specific point in time, similar to wdutil.
By running sudo nohup /usr/bin/sysdiagnose -u &, it will run in the background and write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively (though there is minimal interaction), you can execute sudo /usr/bin/sysdiagnose, which will display a privacy warning. When not 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 navigate to the path. Keep in mind that the file sizes will be around 300MB more or less.
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