How Do You Test OSX No-access
Understanding the Function of Internet Addressing
When connecting to the Internet, you will receive a Public IPv4 address, such as 217.56.105.187, or an IPv6 address, like 2000:ce0f:aaae:c965:9465:48f1:5407:b3ee. You can verify this information at https://test-ipv6.com/. However, attempting to convey these addresses to individuals who are not technologically inclined, or mentioning MAC addresses like 33:8c:cc:13:7b:eb, can lead to errors and complexity. Moreover, this does not provide historical data, especially when encountering past issues.
Navigating the World Wide Web
In order to access a website, such as https://bernhard.biz, your computer first connects to a DNS server to convert the host portion (bernhard) combined with the Top Level Domain (biz) of the URL into an IP address, like 57.78.44.235. Your computer and browser include its type in all web requests, for example: Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Significance of Default Gateways
The default gateway typically has an automatically assigned address through DHCP. This may appear as a default gateway like 192.0.0.150 (although they usually end in .1 or .254 based on the scope size), and serves as the point where your computer forwards all its traffic for further routing. For IPv6, you can find an extensive guide on how-to-fix-ipv6-connectivity/, or verify 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 192.0.0.150 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:f21d:479d:442a:d3a3%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): {47.207.219.164, 240.168.174.141}
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 33:8c:cc:13:7b:eb
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 7a:dc:ac:2b:ba:89
}
Fixing Connection Issues for Wired and Wireless Networks
When it comes to transferring data to your router, you have the option of using a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
No matter which version of OSX/macOS you are using, whether it’s 10.11.1, 11.1.3, or 12.2.6, there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that prefer remote work and Work From Anywhere (WFA) setups.
Useful Built-in Scripts
One valuable tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings to the CLI and can be configured to generate specific troubleshooting logs. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although many of them are only relevant to wireless settings, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs at /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose, which will prompt 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. Keep in mind that the file sizes are around 300MB.
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