How Do You Check MacOS Internet
Understanding Internet Address Allocation
When connecting to the Internet, you are assigned a Public IPv4 address, for example, like 219.211.41.250, or an IPv6 address such as 2000:9017:8cf7:5069:92:be24:5a9c:1e09. Verifying this information can be done by visiting https://test-ipv6.com/. However, explaining and communicating these addresses to non-technical individuals can be prone to error and complexity, especially when dealing with MAC addresses like 1e:7e:22:cc:4a:e8. Moreover, historical data may not be accessible, especially during previous issues.
Navigating the World Wide Web
To access a webpage like https://hilpert-damore.name, your computer initially connects to a DNS server to translate the host portion (hilpert-damore) combined with the Top Level Domain (name) of the URL to an IP address, for example, 114.106.143.200. Additionally, your computer and browser send their type with all web requests, such as Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A.
Understanding the Significance of Default Gateways
Default gateways are typically automatically configured addresses via DHCP. For instance, you may be assigned a default gateway like 192.0.0.181 (usually ending in .1 or .254 based on the scope size), to which your computer sends all its traffic for routing onwards. For IPv6, detailed instructions can be found at how-to-fix-ipv6-connectivity/, but the process can also be verified on Mac or Linux by 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 192.0.0.181 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:a603:c872:1d22:2847%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): {65.4.206.51, 125.26.148.238}
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 1e:7e:22:cc:4a:e8
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 fd:f9:89:0f:ec:ff
}
Fixing Connectivity Issues for Wired and Wireless Networks
When transmitting data at the physical and data layer, you have the option to use either a wired or wireless (Wi-Fi) medium to send data to your router.
Troubleshooting Tips for Apple macOS / OSX Users
Regardless of whether you are using OSX/macOS versions such as 10.13.1, 11.6.2, or 12.1.1, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a series of related values over time. This is where automated remote troubleshooting becomes particularly valuable, especially for teams that embrace remote work and the Work From Anywhere (WFA) concept.
Useful Built-in Scripts for Troubleshooting
On OSX/macOS, the sudo wdutil info is a useful tool that provides a dump to the CLI of current wireless settings, and can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only point-in-time data in relation to wireless, similar to wdutil.
To run sysdiagnose in the background and write logs to /var/tmp/<blah>.tar.gz, you can use the command: sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can use: sudo /usr/bin/sysdiagnose, although it will give a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp to find the logs. However, be aware that the file sizes can be around 300MB.
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