How Can I Check Mac IP Settings
Understanding Internet Protocol Addresses
When using the Internet, you are assigned a specific Internet Protocol (IP) address. This can be in the form of a Public IPv4 address such as 14.213.227.38 or an IPv6 address like 2000:bd4:72f3:8f63:c98e:431:565a:730f. You can verify your IP address by visiting https://test-ipv6.com/. However, relaying these addresses, or even referring to MAC addresses like dd:4c:dd:a9:78:69, can be complex and prone to errors, especially for those not well-versed in technology.
Navigating the World Wide Web
When typing in a web address, for example, https://hand.name, your computer first contacts a Domain Name System (DNS) server. The host portion (hand) combined with the Top Level Domain (name) is translated into an IP address, such as 185.249.13.182. Additionally, your computer and browser share crucial information with all web requests, such as the type of browser being used Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts).
The Significance of Default Gateways
The default gateway is typically an address assigned through Dynamic Host Configuration Protocol (DHCP). This address, such as 10.98.100.119 (commonly ending in .1 or .254 based on the scope size), is where your computer sends all its traffic to be routed onwards. For IPv6, a detailed explanation is available at how-to-fix-ipv6-connectivity/, and can be verified on Mac or Linux using the following query:
### 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 10.98.100.119 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:f1d6:63ae:2c92:b4d4%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): {250.68.68.4, 243.29.226.81}
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 dd:4c:dd:a9:78:69
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 70:b6:6f:d4:e4:68
}
Troubleshooting and Resolving Wired and Wireless Issues
When it comes to transmitting data to your router, you may be using a wired or wireless (Wi-Fi) medium at the physical and data layer.
Solutions for Apple macOS / OSX Users
Regardless of the version of OSX/macOS you are using, whether it’s 10.13.2, 11.4.1, or 12.1.9, there are various tools available for resolving issues. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that embrace remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
A highly useful tool on OSX/macOS is the sudo wdutil info, which provides a dump of current wireless settings to the CLI, and can also be configured to generate specific troubleshooting logs. Additionally, the sysdiagnose tool can be used to create a wide range of logs, although much of it is only in relation to wireless, 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 an interactive run (although there isn’t much interaction), you can execute sudo /usr/bin/sysdiagnose and it 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 point Finder to the path. Keep in mind that the file sizes are approximately 300MB.
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