How To Fix Mac IP Settings
Understanding Internet Address Assignment
When using the Internet, you are assigned either a Public IPv4 address (e.g. 7.70.112.87) or an IPv6 address (e.g. 2000:dc48:debd:7317:3287:bca0:59be:11b9). You can verify this by visiting https://test-ipv6.com/. However, communicating these addresses, or even mentioning MAC addresses like 40:58:bd:27:d1:0a, can be prone to errors and become complex, especially for non-technical individuals. Furthermore, this method does not provide any historical data, particularly from previous incidents.
Navigating Web Pages
To access a webpage such as https://deckow.io, you first connect to a DNS server. This server translates the combination of the host portion (deckow) and the Top Level Domain (io) of the URL into an IP address, such as 157.67.59.130. With every web request, your computer and browser transmit their type, for instance:
Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
Significance of Default Gateway Configuration
Typically, your default gateway is automatically configured through DHCP, resulting in an address like 192.0.0.115 (commonly ending in .1 or .254 depending on the scope size). This is where your computer directs all its traffic for onward routing. For IPv6, you can refer to our in-depth tutorial on how-to-fix-ipv6-connectivity/, or check on Mac or Linux with:
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 192.0.0.115 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:fdb4:86db:23c5:6caa%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): {215.2.53.92, 206.199.45.0}
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 40:58:bd:27:d1:0a
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 77:c0:7c:0d:61:19
}
Addressing Connectivity Issues: Wired vs. Wireless
When it comes to transmitting data to your router, you might be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Solutions for Apple macOS / OSX Users
Irrespective of whether you are running on OSX or macOS version 10.14.6, 11.1.2, or 12.1.3, there are various tools available for troubleshooting. However, these manual interventions and scripts do not provide a set of interconnected values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that are embracing remote work and Work From Anywhere (WFA).
Utilizing Pre-Installed Scripts
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 set up to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool offers a more comprehensive approach by generating a wide range of logs, although much of it is only relevant to wireless settings, 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 &. For an interactive run, use the command sudo /usr/bin/sysdiagnose, which may trigger a privacy warning. When not run in the background, it should open Finder in the correct location, otherwise, you can navigate to /var/tmp or use Finder with Cmd+Shift+G to locate the path. Keep in mind that the file sizes are approximately 300MB.
Possibly Helpful Videos
P.S. Tips For Remote Network and Client Support
Digital work requires reliable connectivity. Whether for low latency or regular data streams, Wi-Fi, DNS, and network issues cause teams to lose time and productivity. Even worse is when support teams waste time trying to recreate and isolate issues! See how PanSift saves time, money, and frustration on all sides with instant remote troubleshooting 🏠🏝🛰.
