Check Apple Connectivity
Explanation of Internet Protocol Addressing
When it comes to the Internet, you could be assigned a Public IPv4 address such as 152.41.60.73 or an IPv6 address like 2000:87a0:4d83:7ac0:b10e:9bd1:9e9:1883. Verifying this can be done at https://test-ipv6.com/. However, attempting to convey these addresses, or even referencing MAC addresses like 0c:a9:32:80:55:b3, can be prone to errors and become complex for individuals who are not as technologically inclined. Moreover, these methods do not provide any historical information, especially from past occurrences of issues.
Initial Approach to Accessing Websites
When wanting to access a web page such as https://rempel.com, the first step is reaching out to a DNS server to convert the host portion (rempel) together with the Top Level Domain (com) of the URL into an IP address like 85.134.65.163. Interestingly, your computer and browser send this information along with every web request, such as Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0.
Significance of Default Gateways
The default gateway usually possesses an address that is automatically configured via DHCP. This default gateway, like 192.0.0.88 (although they typically end in .1 or .254 depending on the scope size), serves as the location where your computer directs all its traffic to be rerouted. Information on how to rectify IPv6 connectivity is available in our in-depth analysis at how-to-fix-ipv6-connectivity/ but can also be verified on Mac or Linux using the following method:
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 192.0.0.88 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 fe80:1389:d9ae:2bc1:6ad5%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): {149.166.174.19, 21.245.5.5}
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 0c:a9:32:80:55:b3
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 20:d5:e6:52:d9:f3
}
How to Resolve Issues with Wired and Wireless Connections
When transferring data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Effective Troubleshooting Techniques for Apple macOS / OSX
Regardless of whether you are running OSX/macOS versions such as 10.13.7, 11.1.1, or 12.3.2, there are various tools available for troubleshooting. However, these manual processes and scripts do not provide a set of correlated values over time. This is where remote automated troubleshooting becomes essential, particularly for teams that are adapting to remote work and Work From Anywhere (WFA) practices.
Useful Built-in Tools for Troubleshooting
One of the useful tools on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI and can also be configured to generate specific logs for troubleshooting. Moreover, the sysdiagnose tool offers a comprehensive approach by generating a wide range of logs (although many are point-in-time related to wireless, similar to wdutil).
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz. Alternatively, running sudo /usr/bin/sysdiagnose interactively (despite minimal interaction) will prompt a privacy warning and open Finder in the correct location. However, be cautious of the file sizes, which are around 300MB.
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