How Do You Support Common Wifi No Access
Understanding Internet Addressing
When using the Internet, individuals may receive a Public IPv4 or IPv6 address. These addresses can be verified using https://test-ipv6.com/. However, communicating these addresses, or even identifying MAC addresses, can become challenging and error-prone for those who are not technologically inclined. Moreover, it does not provide any historical data, especially during past issues.
Navigating the World Wide Web
Accessing a website such as https://haag-kassulke.co involves initially contacting a DNS server to translate the URL’s host portion and Top Level Domain to an IP address. When making web requests, your computer and browser convey their type, such as Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16.
Understanding the Significance of Default Gateways
The default gateway is typically an automatically assigned address via DHCP, such as 10.152.99.31 (commonly ending in .1 or .254 based on the scope size). This is where your computer forwards all traffic to be routed. For IPv6, more detailed information is available at how-to-fix-ipv6-connectivity/. On Mac or Linux systems, this can be verified using:
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 10.152.99.31 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 fe80:8919:e599:84e0:f55b%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): {92.24.230.5, 107.253.99.161}
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 f2:e1:b5:9d:c5:99
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 1a:92:f4:4a:3b:36
}
Resolving Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
No matter the version of OSX/macOS you’re using - whether it’s 10.11.2, 11.1.1, or 12.1.9 - there are various tools available for troubleshooting. However, these manual actions and scripts fail to provide a series of correlated values over time. This is where automated remote troubleshooting becomes invaluable, particularly for teams that have embraced remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
One particularly useful tool on OSX/macOS is the 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 at a specific point in time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & will execute it in the background and write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively (although there isn’t much interaction), you can use sudo /usr/bin/sysdiagnose, which will prompt 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. Be cautious of the file sizes, which are around 300MB more or less.
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