How Do You Check Wifi No Access
Understanding Internet Protocol Addressing
When using the Internet, it’s common to have a unique identifier known as an IP address, such as 12.136.167.43 for IPv4 or 2000:a894:f9b5:3985:6b50:73d2:fb5f:edea for IPv6. Verifying this information is possible by visiting https://test-ipv6.com/. However, conveying these addresses to non-technical individuals or even mentioning MAC addresses like 81:3e:e4:4b:0f:67 can quickly become complicated and prone to errors. This method also lacks historical data.
Navigating the World Wide Web
When accessing a website, such as https://fisher.info, the first step involves reaching out to a DNS server to translate the host portion (fisher) and the Top Level Domain (info) to an IP address, like 240.198.6.186. It’s worth noting that your computer and browser includes its type in all web requests, for example: Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
The Significance of Default Gateways
The default gateway is typically an automatically configured address obtained through DHCP. For instance, you might receive a default gateway of 10.48.204.154 (commonly ending in .1 or .254, depending on the scope size), which serves as the destination for all the traffic routed by your computer. For IPv6 connectivity troubleshooting, a comprehensive guide is available at how-to-fix-ipv6-connectivity/. On Mac or Linux, you can verify this information 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 10.48.204.154 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:b0a9:9432:6784:d0d9%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): {115.146.124.195, 121.65.5.24}
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 81:3e:e4:4b:0f:67
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 7c:5c:3c:d0:0e:e1
}
Troubleshoot 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) medium at the physical and data layer.
Resolving Connectivity Problems on Apple macOS / OSX
Regardless of the version of OSX/macOS you are using, whether it’s 10.15.1, 11.3.6, or 12.0.2, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that embrace remote work and Work From Anywhere (WFA).
Utilizing Built-in Tools for Troubleshooting
One valuable tool for troubleshooting on OSX/macOS is sudo wdutil info, which provides a dump of the current wireless settings to the CLI, and can be configured to generate specific logs for troubleshooting purposes. Furthermore, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only relevant to wireless settings at a specific point in time, similar to wdutil.
To run sysdiagnose in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively (even though there is minimal interaction), use sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. The non-background execution of the command 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 approximately 300MB or slightly larger.
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