How To Fix MacOS IP Settings
Understanding How Internet Addressing Functions
When using the Internet, you may receive a Public IPv4 address, such as 181.7.238.45, or an IPv6 address, such as 2000:f2a5:18ba:922e:1cdd:54d1:1b99:d75e. Verification of this can be done at https://test-ipv6.com/. However, conveying these addresses to individuals who are not knowledgeable in technology, or even referencing MAC addresses like bc:c5:33:bb:8d:65, can be prone to errors and quickly become complex. Furthermore, this does not provide any historical data, especially from past issues.
Navigating the Internet
Accessing a web page such as https://schmidt.co initially involves reaching out to a DNS server to convert the host portion (schmidt) combined with the Top Level Domain (co) of the URL into an IP address, such as 192.7.28.111. Every web request from your computer and browser includes the respective type, for example:Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
Significance of Default Gateways
Typically, your default gateway is an address configured automatically via DHCP. An example of a default gateway is 192.0.0.247 (although they usually end in .1 or .254 depending on the scope size), and this is where your computer directs all its traffic to be routed further. For IPv6, detailed instructions are provided in our article how-to-fix-ipv6-connectivity/, or it can be verified on Mac or Linux 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 192.0.0.247 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:df1:1f30:8bac:f2fa%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): {195.97.217.218, 90.35.113.116}
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 bc:c5:33:bb:8d:65
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 cd:3a:d1:10:59:73
}
Resolving Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you might be using either a wired or a wireless (Wi-Fi) medium at the physical and data layer.
Tips for Apple macOS / OSX Troubleshooting
No matter which version of OSX/macOS you are running, such as 10.14.1, 11.0.8, or 12.0.3, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams engaging in remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
One useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of the current wireless settings to the CLI and can also be configured to generate specific troubleshooting logs. Additionally, the sysdiagnose tool offers more comprehensive logging capabilities, although much of it is only related to wireless and is point-in-time specific, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in /var/tmp/<blah>.tar.gz. For interactive use (although there is minimal interaction), you can run sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. When not run in the background, it should open Finder in the appropriate location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G to locate the files. 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 🏠🏝🛰.
