How To Check Wifi No Access

Understanding Internet Addressing When using the Internet, you are assigned a unique Public IPv4 address, such as 44.66.25.210, or an IPv6 address, such as 2000:447b:f7bb:e1be:b0f:ccf9:1265:cc71. These addresses can be verified at https://test-ipv6.com/. However, articulating and handling these addresses, as well as MAC addresses like fe:75:60:d6:19:b9, can be challenging for individuals who are not technically inclined. Understanding Internet Addressing When using the Internet, you are assigned a unique Public IPv4 address, such as 44.66.25.210, or an IPv6 address, such as 2000:447b:f7bb:e1be:b0f:ccf9:1265:cc71. These addresses can be verified at https://test-ipv6.com/. However, articulating and handling these addresses, as well as MAC addresses like fe:75:60:d6:19:b9, can be challenging for individuals who are not technically inclined.

Understanding Internet Addressing

When using the Internet, you are assigned a unique Public IPv4 address, such as 44.66.25.210, or an IPv6 address, such as 2000:447b:f7bb:e1be:b0f:ccf9:1265:cc71. These addresses can be verified at https://test-ipv6.com/. However, articulating and handling these addresses, as well as MAC addresses like fe:75:60:d6:19:b9, can be challenging for individuals who are not technically inclined. Additionally, these addresses do not provide historical data, particularly from past incidents.

When attempting to access a web page, such as https://nitzsche.name, the initial step involves reaching out to a DNS server to convert the host part (nitzsche) along with the Top Level Domain (name) of the URL into an IP address, such as 218.103.115.117. Your computer and browser include its type in all web requests, as exemplified by:
Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16

Significance of Default Gateways

The default gateway is typically an address that is automatically configured via DHCP. In most cases, you will be assigned a default gateway like 172.16.229.157 (with the final digits usually being either .1 or .254 based on the scope size), which serves as the point where your computer forwards all its traffic for further routing. For a more in-depth exploration of IPv6, you can refer to our article on how-to-fix-ipv6-connectivity/. If you are using a Mac or Linux system, you can verify this by running the following command:

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  172.16.229.157    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   fe80:607e:5991:a6f7:5998%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): {0.189.197.48, 56.136.131.198}
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 fe:75:60:d6:19:b9
  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 e9:30:81:6a:3f:93
}

addressing issues with wired and wireless connections

When it comes to sending data to your router, you may be using a wired or wireless (Wi-Fi) medium at the physical and data layer.

troubleshooting on Apple operating systems

Regardless of whether you are using OSX or macOS, be it 10.12.3, 11.6.3, or 12.2.8, there is a variety of troubleshooting tools available. 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 remote work and Work From Anywhere (WFA) setups.

useful built-in scripts

On OSX/macOS, sudo wdutil info is a useful tool that provides a dump of current wireless settings to the CLI, and it 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 only relevant at a specific point in time in relation to wireless, similar to wdutil.

To run sudo nohup /usr/bin/sysdiagnose -u & in the background and write logs to /var/tmp/<blah>.tar.gz. For interactive use, you can run sudo /usr/bin/sysdiagnose which will give a privacy warning. When not run in the background, it 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 about 300MB more or less.

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