Fix Wifi Internet Issues
Functioning of Internet Addressing
When using the Internet, individuals are assigned Public IPv4 addresses, such as 138.7.102.125, or IPv6 addresses, like 2000:f0e9:936a:f769:5866:76c3:f4b1:a8fc. Verification of these addresses can be done at https://test-ipv6.com/. However, it can be challenging for those unfamiliar with technical jargon to communicate these addresses or MAC addresses like 8a:95:31:58:94:e6, leading to errors and complications. Moreover, this method does not provide historical data, particularly from previous incidents.
Navigating the World Wide Web
To access a website, such as https://feil-medhurst.biz, you initially connect to a DNS server to convert the host portion (feil-medhurst) in combination with the Top Level Domain (biz) of the URL into an IP address, like 125.180.5.77. Additionally, your computer and browser convey their type with every web request, for example:
Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
Significance of Default Gateways
The default gateway is typically an automatically assigned address through DHCP. It typically appears as a default gateway, such as 172.25.53.47 (often ending in .1 or .254, depending on the scope size), and serves as the point to which your computer forwards all of its traffic to be routed further. For a detailed guide on IPv6, refer to how-to-fix-ipv6-connectivity/, or check on Mac or Linux 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 172.25.53.47 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 fe80:2583:1c80:f530:287f%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): {97.190.169.125, 253.52.146.25}
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 8a:95:31:58:94:e6
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 31:d8:1c:4e:85:52
}
Resolving Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
How to Address Problems on Apple macOS / OSX
Regardless of which version of OSX/macOS you are operating on, whether it’s 10.12.9, 11.4.6, or 12.2.5, there are various troubleshooting tools available. However, these tools and scripts do not provide a set of correlated values over time, making remote troubleshooting automation a valuable solution, especially for remote or Work From Anywhere (WFA) teams.
Utilizing Pre-installed Scripts for Assistance
One 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 troubleshooting logs. Additionally, the sysdiagnose tool can be used to generate a wide range of logs related to wireless, although many of them are point-in-time only, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & will execute the sysdiagnose tool in the background and write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively, you can executesudo /usr/bin/sysdiagnose and it will display 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 approximately 300MB.
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