Support OSX IP Settings

Understanding Internet Addressing When it comes to the Internet, you might be assigned a Public IPv4 address such as 28.207.144.9 or an IPv6 address like 2000:f893:89e3:603c:f0e9:c5cd:dc17:38a3. This information can be verified at https://test-ipv6.com/. However, explaining and working with these addresses, as well as MAC addresses like cb:ed:e9:11:16:b8, can be challenging for non-technical people and also fails to provide historical data on previous issues. Understanding Internet Addressing When it comes to the Internet, you might be assigned a Public IPv4 address such as 28.207.144.9 or an IPv6 address like 2000:f893:89e3:603c:f0e9:c5cd:dc17:38a3. This information can be verified at https://test-ipv6.com/. However, explaining and working with these addresses, as well as MAC addresses like cb:ed:e9:11:16:b8, can be challenging for non-technical people and also fails to provide historical data on previous issues.

Understanding Internet Addressing

When it comes to the Internet, you might be assigned a Public IPv4 address such as 28.207.144.9 or an IPv6 address like 2000:f893:89e3:603c:f0e9:c5cd:dc17:38a3. This information can be verified at https://test-ipv6.com/. However, explaining and working with these addresses, as well as MAC addresses like cb:ed:e9:11:16:b8, can be challenging for non-technical people and also fails to provide historical data on previous issues.

To access a website such as https://lynch.org, you first contact a DNS server to convert the host portion (lynch) combined with the Top Level Domain (org) of the URL into an IP address like 13.163.228.117. Additionally, your computer and browser include its type in all web requests e.g.
Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0

Significance of Default Gateways

Your default gateway is typically an address that is automatically configured via DHCP. It often ends in .1 or .254, depending on the scope size, such as 172.25.188.58, and acts as the point to which your computer sends all its traffic to be routed onwards. For IPv6, detailed instructions can be found in our article how-to-fix-ipv6-connectivity/, and can also 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  172.25.188.58    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   fe80:196e:241d:d423:faa0%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): {195.77.225.101, 103.88.156.198}
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 cb:ed:e9:11:16:b8
  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 bf:53:bb:b9:0b:d8
}

Solutions for Resolving Wired and Wireless Issues

When it comes to transmitting data to your router, you may encounter issues at the physical and data layer whether you are using a wired or wireless (Wi-Fi) connection.

Actions to Take on Apple macOS / OSX

No matter which version of OSX/macOS you are operating on, whether it’s 10.15.7, 11.1.7, or 12.1.6, there are various troubleshooting tools available. However, the manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes essential, especially for teams that have transitioned to remote work and Work From Anywhere (WFA).

Useful Built-in Scripts

One incredibly useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Furthermore, the sysdiagnose tool can be used to generate 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 sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can also execute sudo /usr/bin/sysdiagnose, which will issue a privacy warning. When not run in the background, it should open Finder in the correct location or you can navigate to /var/tmp using Finder with Cmd+Shift+G. Just be cautious of the file sizes, which are typically around 300MB.

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P.S. PanSift Tip For Work From Anywhere Support

Digital work requires reliable connectivity for voice, video, and data. Inevitable Wi-Fi, network, and system issues cause teams to lose time and productivity, or worse, to miss out on opportunities. Whether working from home, a shared space, or an office, and irrespective of the network being managed or unmanaged, forward thinking technical teams embrace smarter tools to save their users and clients time and money! See how PanSift provides instant remote troubleshooting, irrespective of location 🏠🏝🛰.

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