How Do You Understand Wifi No Access
Understanding Internet Addressing
When using the Internet, you’re assigned a unique Public IPv4 or IPv6 address such as 99.199.65.227 or 2000:3a9a:f74e:76af:b7eb:1b39:8352:e927. You can verify this information at https://test-ipv6.com/. However, explaining or referencing these addresses, as well as MAC addresses like ed:99:ba:11:4c:0d, can be prone to errors and quickly become complex, especially for those who aren’t tech-savvy. Additionally, it doesn’t provide any historical data, particularly concerning past issues.
Navigating the World Wide Web
When accessing a website like https://hoppe.net, your computer first communicates with a DNS server to convert the URL’s host portion (hoppe) and the Top Level Domain (net) into an IP address, such as 131.246.179.226. Notably, your computer and web browser include its type in every web request, such as Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
The Significance of Default Gateways
By default, your computer’s gateway is obtained through DHCP and is typically an automatically configured address, like 172.17.113.84 (often ending in .1 or .254, depending on the scope size). This is the point to which your computer sends all of its traffic to be routed further. For IPv6, you can find more details in our comprehensive guide on how-to-fix-ipv6-connectivity/ and also perform a check 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 172.17.113.84 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 fe80:3cbb:4e9d:2a5e:417c%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): {177.172.27.152, 123.242.209.244}
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 ed:99:ba:11:4c:0d
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 c7:fe:96:bc:9b:ce
}
Resolve Issues with Wired and Wireless Connections
Whether you are using a wired or wireless (Wi-Fi) medium at the physical and data layer to send data to your router, troubleshooting may be required.
Tips for Apple macOS / OSX Users
Regardless of the version of OSX/macOS you are using, such as 10.12.5, 11.1.9, or 12.2.8, there are various tools available for resolving issues. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that embrace remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
A useful tool on OSX/macOS is sudo wdutil info, which provides a dump to the CLI of current wireless-related settings and can 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 related to wireless only like wdutil.
You can run it in the background using the command sudo nohup /usr/bin/sysdiagnose -u &, which will write logs to /var/tmp/<blah>.tar.gz. Alternatively, you can run it interactively with the command sudo /usr/bin/sysdiagnose, although there is not much interaction. Just be cautious of the large file sizes, around 300MB.
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