How Can I Understand Wifi No Access
The Basics of Internet Addressing
When using the Internet, you are assigned a unique public IP address, such as 108.34.132.203 for IPv4 or 2000:230f:21e2:8298:e0a9:25f2:210c:ee22 for IPv6. A handy tool to check your IP address is available at https://test-ipv6.com/. However, conveying these addresses and MAC addresses like 25:97:c6:63:f8:01 to non-technical individuals can be prone to errors and quickly becomes complex. Moreover, it lacks the ability to provide historical data.
How Web Access Works
To access a website like https://mante.io, you first connect to a DNS server to translate the host (mante) and the Top Level Domain (io) to an IP address, such as 251.239.232.152. Your computer and browser include information about their type in web requests, for example: Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
Understanding the Importance of Default Gateways
The default gateway, usually automatically assigned through DHCP, is an essential element. It is assigned an address like 192.168.74.68 (often ending in .1 or .254 based on the scope size) and serves as the routing point for all outgoing traffic from your computer. To troubleshoot IPv6 connectivity in Mac or Linux, a detailed guide can be found at 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 192.168.74.68 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 fe80:6a49:7a3e:764f:3799%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): {215.133.136.163, 1.111.126.242}
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 25:97:c6:63:f8:01
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 55:e6:71:22:10:a5
}
Resolving Connectivity Issues for Wired and Wireless Networks
When it comes to transmitting data at the physical and data layer, you have the option of using a wired or wireless (Wi-Fi) medium to send the data to your router.
Troubleshooting Tips for Apple macOS / OSX
Regardless of the version of OSX/macOS you are using, whether it’s 10.13.6, 11.2.9, or 12.3.3, there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a series of correlated values over time, which is why automated remote troubleshooting is essential, especially for teams that have embraced remote work and Work From Anywhere (WFA).
Embedded Tools for Assistance
One incredibly useful tool on OSX/macOS is “sudo wdutil info,” which provides a dump of the current wireless related settings to the CLI. It can also be configured to generate specific logs for troubleshooting. Moreover, the “sysdiagnose” tool can be used to generate a wide range of logs, although much of the information is only relevant at a specific point in time, similar to wdutil.
Running it in the background using “sudo nohup /usr/bin/sysdiagnose -u &” will write logs to “/var/tmp/
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P.S. Tips For Remote Network and Client Support
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