Test OSX No-access
Understanding Internet Addressing
When using the Internet, individuals may have a Public IPv4 address such as 118.81.245.102 or an IPv6 address like 2000:3317:9d16:80e3:95f9:85ec:f456:8450. It is possible to verify these addresses at https://test-ipv6.com/. However, for those who are not familiar with technical terminology, conveying these addresses can be prone to errors and quickly become complex. Moreover, this approach does not provide any historical data, particularly when addressing previous issues.
Navigating the World Wide Web
In order to access a web page like https://harvey.org, an initial step involves accessing a DNS server to convert the host portion (harvey) along with the Top Level Domain (org) of the URL into an IP address like 210.15.167.161. Whenever a web request is made, the computer and browser transmit information about their type, such as Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
The Significance of Default Gateways
Typically, the default gateway is an address that is automatically configured through DHCP. A default gateway, such as 192.168.101.220 (usually ending in .1 or .254 depending on the scope size), serves as the designated location where a computer sends all its traffic to be routed to its final destination. For IPv6, a comprehensive guide can be found at how-to-fix-ipv6-connectivity/ with instructions for verifying on Mac or Linux, using:
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 192.168.101.220 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 fe80:23d3:12b4:931e:6521%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): {172.199.126.107, 80.29.142.241}
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 12:2f:78:bd:c2:9b
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 7f:6a:9d:d2:e3:6b
}
Ways to Solve Connectivity Issues: Wired or Wireless
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.
Tips for Resolving Problems on Apple macOS / OSX
No matter the version of OSX/macOS you have - whether it’s 10.14.8, 11.5.1, or 12.3.4 - there are various troubleshooting tools available. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes essential, especially for teams that embrace remote work and Work From Anywhere (WFA).
Useful Native Scripts
One highly beneficial tool on OSX/macOS is sudo wdutil info, which provides a CLI dump of current wireless settings and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to create a wide range of logs, although many of them are only point-in-time related to wireless, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose, but keep in mind that 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. Be mindful of the file sizes, which are about 300MB or so.
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 🏠🏝🛰.
