Test MacOS Issues
Explanation of Internet Addressing Systems
When using the Internet, it is common to have a public IP address, whether it is an IPv4 address such as 60.15.93.132 or an IPv6 address like 2000:b674:c40a:5a06:d0f1:3e26:bbf8:816d. To verify this, you can visit https://test-ipv6.com/. However, for individuals who are not familiar with technical terms, trying to communicate these addresses or even mentioning MAC addresses like f8:c2:f0:12:22:c2 can be prone to error and become complicated quickly. Additionally, this method does not provide any historical data or information related to past issues.
How to Reach Websites
When attempting to access a website such as https://lowe-thompson.com, the first step involves accessing a DNS server in order to convert the host portion (lowe-thompson) along with the Top Level Domain (com) of the URL to an IP address, such as 186.163.252.153. In fact, every time a web request is made, your computer and browser sends its type, for example: Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Significance of Default Gateways
By default, your gateway is a DHCP-configured address. Usually, the default gateway, such as 192.168.56.250, is where your computer directs all its traffic to be routed further. For IPv6, detailed instructions can be found at how-to-fix-ipv6-connectivity/. However, you can check this on a Mac or Linux by using the following:
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 192.168.56.250 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 fe80:6b73:827d:e588:fd86%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): {182.103.133.208, 162.221.181.161}
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 f8:c2:f0:12:22:c2
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 c9:76:9e:07:cf:53
}
Solutions for Dealing with Wired and Wireless Connectivity Issues
When it comes to sending data to your router, you might be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Effective Strategies for Apple macOS / OSX Users
Regardless of whether you are operating on OSX/macOS versions such as 10.14.1, 11.6.9, or 12.3.1, there are various tools available for troubleshooting. However, manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting proves to be especially beneficial, particularly for teams engaged in remote work and Work From Anywhere (WFA).
Useful Built-in Tools for Troubleshooting
One of the helpful tools on OSX/macOS is the sudo wdutil info, which provides a dump of current wireless settings to the CLI and can be configured to generate specific troubleshooting logs. Furthermore, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only relevant to a specific point in time in relation 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 use sudo /usr/bin/sysdiagnose, but be cautious of the large file sizes of approximately 300MB.
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