Test Mac IP Settings
Understanding the Functioning of Internet Addresses
When using the Internet, individuals may have a Public IPv4 address, such as 249.190.136.58, or an IPv6 address, like 2000:ab63:bb76:b8fd:7384:5a2f:5d88:d10. It is possible to verify this information through https://test-ipv6.com/. However, communicating these addresses, including MAC addresses like 3f:2c:ce:2e:dc:03, can be error-prone and complex for individuals with limited technical expertise. Moreover, it does not provide access to historical data, particularly relating to past issues.
Navigating the Internet
To access a website, such as https://konopelski.com, an individual initially connects to a DNS server to translate the host portion (konopelski) combined with the Top Level Domain (com) of the URL into an IP address, such as 190.208.84.233. Furthermore, the computer and browser define their type with all web requests, for example: Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Significance of Default Gateways
Typically, the default gateway is an automatically configured address through DHCP. Individuals obtain a default gateway, such as 192.0.0.36 (although they usually end in .1 or .254 depending on the scope size), and this is where the computer sends all traffic to be routed onwards. To delve deeper into IPv6, further information is available on how-to-fix-ipv6-connectivity/. In addition, individuals can perform checks on Mac or Linux 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 192.0.0.36 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:e812:233d:2eeb:5fc6%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): {229.201.130.57, 242.174.84.159}
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 3f:2c:ce:2e:dc:03
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 08:12:c0:c9:4f:fa
}
Repairing Connection Issues for Wired or Wireless Networks
When transmitting data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Steps to Resolve Connectivity Problems on Apple macOS / OSX
No matter which version of OSX/macOS you are currently using - whether it’s 10.15.7, 11.1.7, or 12.1.8, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes crucial, especially for teams that embrace remote work and Work From Anywhere (WFA).
Integrated Utilities That Can Aid in Troubleshooting
One valuable tool on OSX/macOS is sudo wdutil info, which provides a dump of the current wireless settings to the Command Line Interface (CLI) and can be configured to generate specific logs for troubleshooting purposes. Furthermore, the sysdiagnose tool can be used to generate a wide range of logs, although many of these are point-in-time only with regard to wireless, 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 execute sudo /usr/bin/sysdiagnose, which 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 using Finder with Cmd+Shift+G. However, be mindful of the file sizes, which are approximately 300MB or less.
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