Check OSX Issues
Understanding Internet Addressing
When using the internet, you are assigned a unique public IP address, such as 100.247.40.43 for IPv4 or 2000:920:d2be:e5c0:7e89:9028:309d:9697 for IPv6. You can verify your address by visiting https://test-ipv6.com/. Explaining and relaying these long and complex addresses, as well as MAC addresses like 24:8d:f1:bd:04:b8, to those not well-versed in technology can prove to be challenging. Furthermore, this method lacks historical data, which is especially important when troubleshooting past issues.
Navigating the Internet
Accessing a website, such as https://dare.name, involves contacting a DNS server to translate the URL’s host section (dare) and its Top Level Domain (name) into an IP address, like 68.175.13.187. In addition, each web request from your computer and browser contains information about its type, such as: Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
The Role of Default Gateways
Your default gateway is often automatically assigned through DHCP and typically appears as an address like 192.0.0.68 (although they usually end in .1 or .254, depending on the scope size). This gateway is responsible for routing all outgoing traffic from your computer. To troubleshoot IPv6 connectivity on Mac or Linux, follow our guide at how-to-fix-ipv6-connectivity/ or use the command line.
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 192.0.0.68 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 fe80:674c:9ed3:860f:50b3%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): {213.112.5.125, 176.246.126.54}
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 24:8d:f1:bd:04: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 fc:47:54:43:21:18
}
Resolving Connectivity Issues for Wired and Wireless Networks
When it comes to transmitting data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
Regardless of whether you are running OSX/macOS version 10.14.7, 11.3.5, or 12.1.4, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time, which is crucial for remote troubleshooting, especially for teams that adopt remote work and Work From Anywhere (WFA) practices.
Utilizing Built-in Scripts for Assistance
One useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings and can be configured to generate specific logs for troubleshooting. Moreover, the sysdiagnose tool can be used to generate a wide range of logs related to wireless, although many of these are point-in-time only, like wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz. Alternatively, you can run sudo /usr/bin/sysdiagnose interactively, which will open Finder in the correct location. However, be cautious of the file sizes, which can be around 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 🏠🏝🛰.
