How Can I Fix OSX Connectivity
Understanding Internet Protocol Addressing
When using the Internet, individuals are assigned either a Public IPv4 address, such as 24.37.71.182, or an IPv6 address, for example, 2000:2642:95bf:4d5c:4819:b14e:da23:cde. These unique identifiers can be verified at https://test-ipv6.com/. However, comprehending and communicating these addresses, including MAC addresses like c7:0d:cf:8d:0a:a7, can be challenging for those without technical knowledge. Moreover, these addresses do not provide historical information, particularly when addressing past issues.
Navigating the World Wide Web
When accessing a website like https://price.org, you initially connect to a DNS server to translate the host portion (price) combined with the Top Level Domain (org) of the URL into an IP address, such as 169.222.1.218. Any web request from your computer and browser includes information about its type, for example: Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
Understanding the Significance of Default Gateways
Default gateways are typically automatically configured addresses through DHCP. Your computer is assigned a default gateway, such as 192.0.0.133 (although they usually end in .1 or .254 depending on the scope size), to which it sends all its traffic for routing. To troubleshoot IPv6 connectivity on Mac or Linux, a detailed guide can be found at how-to-fix-ipv6-connectivity/ but you can also verify using the following commands.
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 192.0.0.133 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:c286:9f57:f264:cfcf%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): {18.56.181.164, 171.10.4.29}
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 c7:0d:cf:8d:0a:a7
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 fc:7e:8c:b5:22:a1
}
Rectifying Connectivity Issues: Wired vs Wireless Solutions
When it comes to transmitting data to your router, the choice between wired and wireless (Wi-Fi) mediums at the physical and data layer can play a crucial role in troubleshooting and fixing connectivity issues.
Effective Solutions for Apple macOS / OSX Users
Regardless of whether you are using OSX/macOS versions such as 10.12.9, 11.5.3, or 12.3.8, there exists a diverse range of troubleshooting tools at your disposal. However, these manual methods and scripts fail to provide a systematic set of interconnected values over a period of time. This is where automated remote troubleshooting takes the lead, especially for teams that have embraced remote work and the Work From Anywhere (WFA) concept.
Leveraging Native Scripts for Assistance
One incredibly beneficial tool on OSX/macOS is sudo wdutil info which provides a comprehensive rundown of the current wireless-related settings through the CLI, along with the option to generate specific logs for troubleshooting purposes. Furthermore, the sysdiagnose tool can be used to generate a wide range of logs, with the drawback being that much of it is only relevant to a specific point in time in relation to wireless, much like wdutil.
To run it in the background and have it write logs to /var/tmp/<blah>.tar.gz, execute the command sudo nohup /usr/bin/sysdiagnose -u &. For interactive operation, you can run sudo /usr/bin/sysdiagnose and it will display a privacy warning. If 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 hover around 300MB, give or take.
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