How Can I Test Mac Internet Connection
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 address such as 229.127.79.31 or an IPv6 address like 2000:9a1:4c85:9292:d23a:b1f4:3465:c187. A convenient way to check your address is by visiting https://test-ipv6.com/. However, conveying these addresses to non-technical individuals, or even identifying MAC addresses like d4:5e:85:2f:d3:a3, can become complicated and prone to errors. Moreover, this method lacks historical data that could be beneficial in troubleshooting past issues.
Navigating the World Wide Web
Accessing a website such as https://gottlieb.net involves initially querying a DNS server to convert the host segment (gottlieb) combined with the Top Level Domain (net) of the URL to an IP address like 102.165.94.201. Interestingly, your computer and browser disclose their specifications with each web request, for example: Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)
The Significance of Default Gateways
Your default gateway is typically an address configured automatically through DHCP. This gateway, such as 192.168.56.15 (usually ending in .1 or .254 based on scope size), is where your computer directs all of its outbound traffic. For a detailed explanation of IPv6 connectivity, refer to our in-depth guide on how-to-fix-ipv6-connectivity/. In addition, you can verify this configuration on Mac or Linux by using:
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 192.168.56.15 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 fe80:23d6:b9b6:42cb:6d53%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): {182.39.227.132, 154.194.37.85}
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 d4:5e:85:2f:d3:a3
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 2d:39:0b:ac:be:72
}
Solutions for Resolving Connectivity Issues
When it comes to transferring data to your router, it’s important to troubleshoot and fix any issues that may arise, whether you’re using a wired or wireless (Wi-Fi) connection.
Steps to Take on Apple macOS / OSX Systems
Regardless of which version of OSX/macOS you’re using, be it 10.14.9, 11.0.1, or 12.2.6, there are several troubleshooting tools at your disposal. However, relying solely on manual actions and scripts may not provide you with a consistent set of correlated values over time. This is where the efficiency of automated remote troubleshooting becomes evident, particularly for teams that have embraced remote work and the Work From Anywhere (WFA) model.
Useful Built-in Scripts
One particularly beneficial tool on OSX/macOS is the sudo wdutil info command, which provides a comprehensive dump of current wireless settings in the CLI and can be configured to generate specific logs for troubleshooting purposes. In addition, the sysdiagnose tool offers a more comprehensive range of logs, although many of these are only relevant to a specific point in time, similar to the wdutil tool.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in the /var/tmp/<blah>.tar.gz directory. On the other hand, you can run sudo /usr/bin/sysdiagnose interactively, which will trigger 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. However, it’s important to be mindful of the file sizes, which are typically around 300MB.
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