How Do You Test OSX Internet Connection
Understanding Internet Protocol Addresses
When using the Internet, you are assigned an identifying number known as an IP address. This number may appear in the form of a Public IPv4 address, such as 171.74.146.70, or an IPv6 address, such as 2000:e412:e46a:7d46:45a7:e7f9:9c9:4885. To check your IP address, you can visit https://test-ipv6.com/. Communicating these addresses, or even mentioning MAC addresses like 4b:f2:1e:7f:27:4f, can be error-prone and confusing, especially for individuals with limited technical knowledge. Furthermore, without historical data, it becomes challenging to address previous issues.
Navigating the World Wide Web
Accessing a webpage, such as https://morar.info, involves initially reaching out to a DNS server to translate the URL’s host portion (morar) and Top Level Domain (info) into an IP address, such as 250.222.107.27. Interestingly, your computer and browser divulge their type with all web requests using a format like: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
Understanding the Significance of Default Gateways
Your default gateway is typically an automatically assigned address through DHCP and usually ends in .1 or .254, depending on the scope size. This is the point where your computer sends all its traffic to be routed onward. For a more in-depth look at IPv6, you can visit how-to-fix-ipv6-connectivity/ or check 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 192.0.0.222 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 fe80:664c:7bd1:2770:2a5d%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): {58.142.32.54, 172.130.153.28}
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 4b:f2:1e:7f:27:4f
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 69:b2:f0:29:6c:ee
}
Resolve Connectivity Issues with Wired and Wireless Networks
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.
Troubleshooting Tips for Apple macOS / OSX Users
Regardless of which version of OSX/macOS you are using, be it 10.11.4, 11.4.8, or 12.3.3, there are various troubleshooting tools available. However, the manual actions and scripts provided do not offer a set of correlated values over time. This is where automated remote troubleshooting becomes particularly beneficial, especially for teams that are advocates of remote work and Work From Anywhere (WFA).
Helpful Built-in Scripts for Troubleshooting
On OSX/macOS, the sudo wdutil info tool can provide a dump of current wireless settings to the CLI, and it can also be configured to generate specific logs for troubleshooting. Furthermore, the sysdiagnose tool offers a more comprehensive option for generating a wide array of logs (although much of it is only relevant to wireless settings, similar to wdutil).
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will 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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