How Can I Fix OSX No-access
The Fundamentals of Internet Addressing
When using the Internet, you are assigned a Public IPv4 or IPv6 address such as 251.186.223.9 or 2000:4bde:7b9:dd07:9074:a974:3d03:f3fa. These addresses can be verified at https://test-ipv6.com/. However, explaining or communicating these addresses, or even MAC addresses such as 31:7a:b2:b0:58:6d, to individuals who are not tech-savvy can be challenging and prone to errors. Moreover, it does not provide any historical data, especially when dealing with past issues.
Navigating the World Wide Web
When accessing a website like https://vonrueden-smitham.com, your initial point of contact is a DNS server, which translates the host portion (vonrueden-smitham) and the Top Level Domain (com) of the URL into an IP address like 180.231.236.177. In addition, your computer and browser send their type with every web request, for example Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts).
Understanding the Significance of Default Gateways
The default gateway is typically an address that is automatically configured via DHCP. It is the point where all traffic from your computer is sent to be routed onward. The default gateway is usually in the form of 172.26.1.138 (ending in .1 or .254 depending on the scope size). For IPv6, a detailed explanation can be found at how-to-fix-ipv6-connectivity/, and on Mac or Linux, it can be checked 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 172.26.1.138 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 fe80:2171:2981:df00:3b94%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): {213.77.1.45, 28.168.175.227}
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 31:7a:b2:b0:58:6d
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 5a:fb:b2:95:34:60
}
Resolve Issues with Wired and Wireless Connections
When it comes to sending data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Steps to Take on Apple macOS / OSX Systems
No matter which version of OSX/macOS you are currently using - whether it’s 10.13.8, 11.4.8, or 12.1.2 - there are various troubleshooting tools available. However, these manual interventions and scripts do not provide a consistent set of correlated values over time. This is where automated remote troubleshooting becomes essential, particularly for teams that are adopting remote work and the concept of Work From Anywhere (WFA).
Utilize Pre-installed Scripts for Assistance
One incredibly useful tool on OSX/macOS is the sudo wdutil info, which provides a dump of current wireless settings to the CLI and can also be configured to generate specific troubleshooting logs. Additionally, the sysdiagnose tool can be used to produce a wide range of logs, although much of it is only relevant at a specific point in time, similar to wdutil.
To run the sysdiagnose tool in the background and generate logs in /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. For an interactive experience (although there isn’t much interaction), use the command sudo /usr/bin/sysdiagnose while being mindful of the large file sizes of around 300MB.
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P.S. PanSift Tip For Work From Anywhere Support
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