Support OSX Connectivity
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 address, such as 222.128.72.106 or an IPv6 address like 2000:7ddd:4360:cdee:31a5:f3ee:b95a:b133. These addresses can be verified at https://test-ipv6.com/. However, conveying these addresses, or even MAC addresses like 16:ce:78:00:86:20, to individuals who are not well-versed in technology can be prone to errors and quickly become complex, especially considering the lack of historical data.
Navigating the World Wide Web
When attempting to access a website such as https://okon.biz, the first step is to access a DNS server that translates the host portion (okon) combined with the Top Level Domain (biz) of the URL into an IP address, like 224.102.50.24. Additionally, your computer and browser transmit its type with every web request, for example: Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
The Significance of Default Gateways
Typically assigned automatically through DHCP, your default gateway, such as 172.26.185.166 (often ending in .1 or .254 based on the scope size), is where your computer sends all its traffic to be routed onwards. Further details on IPv6 can be found in our in-depth discussion on how-to-fix-ipv6-connectivity/, or they can be checked on Mac or Linux.
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 172.26.185.166 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:a191:6a50:f9e5:c916%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): {124.163.49.238, 215.184.108.85}
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 16:ce:78:00:86:20
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 3d:d5:9d:93:7a:84
}
Resolving Issues with Wired and Wireless Connections
When it comes to sending data to your router, you may be using a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Solutions for Apple macOS / OSX
Regardless of the version of OSX/macOS you are using, whether it’s 10.12.6, 11.1.3, or 12.3.4, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that are embracing remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
On OSX/macOS, a useful tool is sudo wdutil info, which provides a dump of current wireless related settings to 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 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, if you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose, although there is not much interaction. Just be mindful of the file sizes, which are approximately 300MB more or less.
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