How To Check MacOS Internet
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 address, such as 57.187.100.121, or an IPv6 address, like 2000:6448:e3b5:5779:be6d:8ea0:3ab5:91c2. These addresses can be verified through https://test-ipv6.com/. However, conveying these addresses to non-technical individuals, or even referencing MAC addresses like 3f:ad:27:34:a6:10, is prone to errors and can become complex. Moreover, it does not provide any historical data, especially when troubleshooting past issues.
Navigating the World Wide Web
When accessing a website, such as https://schmeler-adams.io, you first connect to a DNS server to translate the URL’s host portion (schmeler-adams) combined with its Top Level Domain (io) to an IP address, such as 91.37.147.92. Your computer and browser send their types with all web requests, e.g. 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
Typically configured automatically through DHCP, your default gateway is the address to which your computer sends all its traffic for routing onwards. This is usually an address like 10.161.182.6 (often ending in .1 or .254, depending on the scope size). For troubleshooting IPv6 connectivity, you can find detailed instructions at how-to-fix-ipv6-connectivity/, or by using diagnostic commands in 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 10.161.182.6 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 fe80:7585:ca15:2547:b952%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): {79.147.245.229, 58.143.64.79}
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 3f:ad:27:34:a6:10
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 df:42:8b:ec:d3:ef
}
Tips for Resolving Wired and Wireless Connectivity Issues
When it comes to transmitting data to your router, you may be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Strategies for Addressing Problems on Apple macOS / OSX
Regardless of whether your operating system is OSX/macOS 10.12.6, 11.2.1, or 12.2.6, there are various tools available for troubleshooting. Unfortunately, these manual actions and scripts do not provide a series of interconnected values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that adopt remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
One useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless-related settings to the CLI, and can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only related to wireless settings and is point-in-time data, similar to wdutil.
To run sysdiagnose in the background and have it write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, use the command sudo /usr/bin/sysdiagnose, which 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 using Finder with Cmd+Shift+G to locate the file. Be mindful of the file sizes, which 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 🏠🏝🛰.
