Fix MacOS Connectivity
alse
Understanding the Functioning of Internet Addressing
When using the Internet, you might be assigned a Public IPv4 address such as 132.182.129.200 or an IPv6 address like 2000:bc1e:7342:2227:297:4204:3505:8f88. You can verify this information at https://test-ipv6.com/. However, for individuals who are not technically inclined, conveying these addresses, or even mentioning MAC addresses like 9d:f9:94:8e:37:87, can be prone to errors and can become complex rapidly. Furthermore, this method does not offer any historical data (especially when previous issues occurred).
Navigating the Internet and the Process of Lookups
In order to access a website like https://hodkiewicz-parker.info, you first connect to a DNS server to convert the host part (hodkiewicz-parker) combined with the Top Level Domain (info) of the URL, to an IP address such as 203.145.100.225. Your computer and browser actually sends its type with 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 Crucial Role of Default Gateways
Your default gateway is typically an automatically configured address via DHCP. You receive a default gateway like 192.0.0.252 (although they usually end in .1 or .254 based on the scope size) and this is where your computer sends all its traffic to be routed onwards. For IPv6, we have an in-depth guide on how-to-fix-ipv6-connectivity/ but you can 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 192.0.0.252 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:db37:f57:b89d:3ac6%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): {153.152.49.36, 242.96.32.170}
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 9d:f9:94:8e:37:87
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 c9:c7:bf:72:46:74
}
Solutions for Resolving Issues with Wired and Wireless Connections
When it comes to transferring data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Steps to Take on Apple macOS / OSX
No matter which version of OSX/macOS you are using, whether it’s 10.15.5, 11.0.7, or 12.3.1, 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 invaluable, especially for teams that are embracing remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts and Commands
An extremely useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump to the CLI of current wireless related settings 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 many of them are point-in-time only in relation to wireless, similar to wdutil.
sudo nohup /usr/bin/sysdiagnose -u & will run it in the background and it will write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (though there is not much interaction), you can run 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 using Finder with Cmd+Shift+G to point to the path. Just be aware of the file sizes, which are around 300MB more or less.
Related 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 🏠🏝🛰.
