How Do You Support MacOS IP Settings
The Functionality of Internet Addressing
When using the Internet, you may be assigned a Public IPv4 address such as 181.94.101.115 or an IPv6 address like 2000:a70e:42ff:80ae:cd1a:8f10:c5fb:cc2. Verification can be done using https://test-ipv6.com/. However, conveying these addresses to non-technical individuals or mentioning MAC addresses like 20:9e:c1:67:4e:69 can be error-prone and complex. In addition, this method does not provide historical data, especially related to past issues.
Navigating the Internet
When attempting to access a website like https://kertzmann.net, the first step is to reach a DNS server in order to convert the host portion (kertzmann) in combination with the Top Level Domain (net) of the URL into an IP address, such as 179.36.120.189. Your computer and browser include its type in all web requests, for example: 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
Usually, your default gateway is an automatically configured address via DHCP. A typical default gateway could be 192.0.0.240 (although they typically end in .1 or .254 depending on the scope size) and this is where your computer forwards all its traffic to be routed to its destination. For IPv6, we have an extensive guide available at how-to-fix-ipv6-connectivity/ or you can verify using Mac or Linux.
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 192.0.0.240 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:f25d:d02f:285f:ebd2%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): {77.56.158.19, 220.239.126.20}
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 20:9e:c1:67:4e: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 1d:f8:03:4d:5d:f4
}
Fixing Network Connectivity Issues
When it comes to sending data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Network Problems on Apple Devices
Regardless of whether you are running on OSX/macOS version 10.15.7, 11.3.8, or 12.3.7, 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 essential, especially for teams that have adopted remote work or Work From Anywhere (WFA).
Useful Built-in Tools
One tool that can be very handy 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. Additionally, the sysdiagnose tool can generate a wide range of logs, although many are only for a specific point in time in relation to wireless, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose and it will give a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp manually. 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 🏠🏝🛰.
