How Do You Understand Wifi Issues
Understanding Internet Addressing
When it comes to the Internet, you may have a Public IPv4 address, such as 37.152.205.249, or an IPv6 address like 2000:bb33:bbac:70b0:7288:f5b6:8f51:7ab8. Verifying this information can be done using https://test-ipv6.com/. However, for those who are not tech-savvy, communicating these addresses or identifying MAC addresses like 40:5b:88:40:ce:03 can be prone to error and quickly become complex. Moreover, this method does not provide any historical data, especially when dealing with past issues.
Navigating the World Wide Web
In order to access a website like https://abshire.com, you first connect to a DNS server to convert the host portion (abshire) together with the Top Level Domain (com) of the URL into an IP address, such as 38.52.254.93. Your computer and browser sends its type along with every web request, for example:Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
Understanding the Significance of Default Gateways
The default gateway is typically an address that is automatically configured via DHCP. This may be a default gateway like 192.168.244.193 (although they often end in .1 or .254, depending on the scope size), and it is where your computer sends all its traffic to be routed onwards. For IPv6, there is a detailed exploration available at how-to-fix-ipv6-connectivity/, but you can verify this on Mac or Linux using 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 192.168.244.193 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 fe80:9b5f:8b73:9ea5:9ebc%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): {33.187.176.198, 86.165.108.10}
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 40:5b:88:40:ce:03
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 ac:d1:b0:36:c5:5b
}
Diagnosing and Resolving Connectivity Issues, Wired and Wireless
When it comes to transferring data, whether through a physical connection or over a Wi-Fi network, troubleshooting connectivity issues is crucial.
How to Resolve Connectivity Problems on Apple’s Operating Systems
Regardless of the version of macOS or OSX being used, such as 10.14.8, 11.2.9, or 12.2.2, there are various tools available for diagnosing and resolving connectivity issues. However, these tools and manual actions do not provide a continuous set of related values over time. This is where automated remote troubleshooting becomes invaluable, particularly for remote teams and those working from different locations.
Using Pre-installed Scripts for Troubleshooting
On OSX/macOS, the sudo wdutil info command is a useful tool that provides current wireless settings to the command-line interface and can be configured to generate specific logs for troubleshooting. In addition, the sysdiagnose tool can be used to generate a wide range of logs, although some of it is only relevant to wireless connectivity, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in the /var/tmp/<blah>.tar.gz directory. For an interactive mode (although there is minimal interaction), running sudo /usr/bin/sysdiagnose will result in a privacy warning and open Finder in the correct location, or users can navigate to /var/tmp in Finder using Cmd+Shift+G. It is important to note that the file sizes are approximately 300MB.
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