How To Fix Apple No-access
Understanding Internet Address Structure
When connecting to the Internet, you are assigned a Public IPv4 address, such as 84.22.244.126, or an IPv6 address, like 2000:cd32:aadf:28b:8939:10fd:f385:9a46. Verification of these addresses can be done at https://test-ipv6.com/. However, the communication of these addresses, as well as MAC addresses like 23:89:22:5f:2b:25, can be error-prone and complex, particularly for individuals unfamiliar with technology. Moreover, this method lacks access to historical data, especially for previous problems.
Navigating Web Pages
When accessing a web page, e.g., https://lubowitz.net, an initial contact is made with a DNS server to translate the combination of the host portion (lubowitz) and the Top Level Domain (net) into an IP address, such as 200.213.84.132. All web requests from your computer and browser include its type, as evidenced by Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285.
Significance of Default Gateways
Typically, your default gateway is automatically configured through DHCP and takes the form of an address like 192.0.0.74 (although the end digits generally vary depending on the scope size). This gateway serves as the central passageway for all outgoing traffic from your computer. For details on checking IPv6 connectivity on Mac or Linux, visit how-to-fix-ipv6-connectivity/.
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 192.0.0.74 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 fe80:1a8c:f20e:3f21:a3c0%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): {140.158.83.90, 244.96.23.118}
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 23:89:22:5f:2b:25
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 6a:72:c1:43:16:99
}
Fixing Connectivity Issues with Wired and Wireless Networks
When it comes to transmitting data to your router, you may be using either a wired or wireless (Wi-Fi) connection at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX Users
Regardless of whether you are using OSX/macOS 10.15.3, 11.3.5, or 12.0.1, there are various troubleshooting tools available. However, manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes particularly valuable, especially for teams that prioritize remote work and Work From Anywhere (WFA).
Helpful Built-in Scripts
One valuable tool for OSX/macOS users is sudo wdutil info, which provides a dump of current wireless settings to the CLI 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 much of it is only relevant to wireless settings and is not continuous like wdutil.
To run it in the background and generate logs in /var/tmp/<blah>.tar.gz, use the following command: sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, use sudo /usr/bin/sysdiagnose and follow the instructions. However, be mindful of the large file sizes of about 300MB.
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