How Do You Check Wifi Connectivity
Understanding the Functioning of Internet Addressing
When using the Internet, individuals can obtain a Public IPv4 address, such as 142.158.205.201, or an IPv6 address like 2000:9372:7d2f:34ef:1115:e6b0:5807:eed0. Verification of this can be done at https://test-ipv6.com/. However, attempting to communicate these addresses, or even referencing MAC addresses like e9:fe:76:34:21:c3, can be prone to errors and quickly become complex for those not well-versed in technology. Furthermore, this method does not provide any historical data, especially from previous occurrences of problems.
Navigating the Internet
When wanting to access a web page, such as https://ratke-robel.info, the first step is to contact a DNS server to convert the host portion (ratke-robel) along with the Top Level Domain (info) of the URL to an IP address, such as 224.213.240.139. With each web request, your computer and browser actually conveys its type, as seen in an example like Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A.
Significance of Default Gateways
Typically, the default gateway is an address that is automatically configured via DHCP. A default gateway could be 192.168.193.83 (although they usually end in .1 or .254 depending on the scope size), and it is where a computer sends all its traffic to be routed onwards. For a detailed explanation on IPv6, refer to how-to-fix-ipv6-connectivity/. Verification on Mac or Linux systems can be done 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 192.168.193.83 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:af1a:1150:c754:8c0c%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): {252.136.82.48, 140.235.106.139}
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 e9:fe:76:34:21:c3
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 eb:ab:4d:58:72:31
}
Resolve Connectivity Issues for 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.
Troubleshooting on Apple macOS / OSX
Regardless of the version of OSX/macOS you are using, whether it’s 10.11.7, 11.0.8, or 12.3.6, there are various 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 especially valuable, particularly for teams that have embraced remote work and Work From Anywhere (WFA) practices.
Utilizing Built-in Scripts for Assistance
A very useful tool on OSX/macOS is ‘sudo wdutil info’, which provides a dump to the CLI of current wireless settings, and can also be configured to generate specific troubleshooting logs. Additionally, the ‘sysdiagnose’ tool can be used to generate a wide range of logs, although much of it is only point-in-time information related to wireless, similar to wdutil.
To run ‘sysdiagnose’ in the background, use the command ‘sudo nohup /usr/bin/sysdiagnose -u &’ and it will write logs to ‘/var/tmp/