How Do You Fix OSX Issues
The Operational Mechanism of Internet Addressing
When using the Internet, one might receive a Public IPv4 address such as 224.57.255.246 or an IPv6 address like 2000:5192:201c:65de:78c3:92a2:4766:30eb. This information can be verified on https://test-ipv6.com/. However, for individuals who are not technology-savvy, conveying these addresses, or even referencing MAC addresses like 71:87:45:3d:37:7f, can lead to errors and complexity. Furthermore, this does not offer any historical data, especially when past issues occurred.
Navigating the World Wide Web
Accessing a web page such as https://lebsack.biz involves initially connecting to a DNS server to convert the host section (lebsack) along with the Top Level Domain (biz) of the URL into an IP address like 107.34.85.182. Your computer and browser also send their specifications with all web requests, for example: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
The Significance of Default Gateways
A default gateway is typically an automatically assigned address through DHCP. You receive a default gateway like 192.0.0.77 (although they commonly end in .1 or .254 depending on the scope size) and this is the location where your computer directs all its traffic for further routing. As for IPv6, there is an in-depth discussion available on how-to-fix-ipv6-connectivity/ but you can 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 192.0.0.77 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 fe80:11aa:5572:ac6d:d3%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): {216.251.46.24, 189.35.124.7}
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 71:87:45:3d:37:7f
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 32:b2:3e:90:e5:18
}
Troubleshooting Connection Issues
When it comes to transferring data to your router, you might be using a wired or wireless (Wi-Fi) connection at the physical and data layer.
Tips for Resolving Network Problems on Apple Devices
No matter which version of macOS you have, whether it’s 10.15.2, 11.6.6, or 12.2.2, there are various methods for troubleshooting network issues. However, these manual methods and scripts do not provide a series of interconnected values over time. This is where automated remote troubleshooting becomes particularly useful, especially for teams that support remote work and Work From Anywhere (WFA).
Useful Built-in Tools
One useful tool on macOS is the sudo wdutil info command, which provides a dump of the current wireless settings to the command line interface, and can also be configured to generate specific logs for troubleshooting. Additionally, the more comprehensive sysdiagnose tool can be used to generate a wide range of logs (though much of it is only related to wireless settings at a specific point in time, similar to wdutil).
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in the /var/tmp/<blah>.tar.gz directory. If you prefer to run it interactively, you can run sudo /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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