Test Mac Internet
Understanding the Functioning of Internet Addresses
When using the Internet, you are assigned a Public IPv4 address, such as 132.11.83.64, or an IPv6 address, like 2000:1ae6:7883:60c8:6a05:c126:132d:b3b. A convenient way to verify this is through the website https://test-ipv6.com/. However, for individuals without technical expertise, conveying these addresses, or even referencing MAC addresses like 0e:7a:6b:e4:c0:d1, can be prone to error and complex. This method also lacks historical data, particularly regarding past issues.
Navigating the Internet
When attempting to access a webpage, such as https://padberg-bauch.name, the first step involves contacting a DNS server to convert the host portion (padberg-bauch) combined with the Top-Level Domain (name) of the URL into an IP address, such as 33.162.224.132. Additionally, your computer and browser transmit specific details 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)
Significance of Default Gateways
The default gateway is typically an address automatically configured via DHCP. This address, such as 192.168.237.112 (often ending in .1 or .254 based on the scope size), is where your computer directs all traffic for routing. Detailed instructions for checking on Mac or Linux are available in our comprehensive guide to how-to-fix-ipv6-connectivity/.
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 192.168.237.112 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 fe80:5144:f0c:5e1b:a14c%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): {91.90.144.111, 198.65.194.87}
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 0e:7a:6b:e4:c0:d1
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 6e:81:b4:20:7f:0c
}
Resolve Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you may be using either a wired or a wireless (Wi-Fi) medium at the physical and data layer.
Tips for Apple macOS / OSX Troubleshooting
No matter which version of OSX or macOS you are currently using - whether it’s 10.13.7, 11.6.5, or 12.0.5 - there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting comes in handy, particularly for teams that have adopted remote work and Work From Anywhere (WFA) practices.
Useful Built-in Scripts
An extremely useful tool on OSX/macOS is the sudo wdutil info, which provides a dump of the current wireless related settings in the CLI, 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 relevant to wireless settings at a specific point in time, 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, the command sudo /usr/bin/sysdiagnose can be used, although it will display a privacy warning. When not run in the background, it should open Finder in the correct location, otherwise you can navigate to /var/tmp using Finder with Cmd+Shift+G or via the path directly. However, be mindful of the file sizes, which are typically around 300MB.
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