How Can I Support Apple IP Settings
Understanding the Basics of Internet Addressing
When using the Internet, you are assigned a Public IPv4 address, such as 235.239.44.43, or an IPv6 address, like 2000:f63e:ad3f:51dd:44c4:82ed:a02:85f. You can verify this at https://test-ipv6.com/. However, for those not well-versed in technology, conveying these addresses or MAC addresses like 0f:1d:1b:54:9f:d0 can be prone to errors and quickly become complex. Furthermore, this method does not provide any historical data, especially when encountering previous issues.
Navigating the World Wide Web
When accessing a website such as https://huel-windler.net, you first contact a DNS server to translate the host portion (huel-windler) combined with the Top Level Domain (net) of the URL into an IP address, such as 208.231.90.40. Your computer and browser sends its type with all web requests, for example: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
Recognizing the Significance of Default Gateways
Your default gateway is typically an automatically configured address via DHCP. You are assigned a default gateway, such as 10.243.201.26 (usually ending in .1 or .254 depending on the scope size), where your computer sends all its traffic to be routed onwards. For IPv6, we provide an in-depth guide on how to fix IPv6 connectivity, but you can also check on Mac or Linux with:
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 10.243.201.26 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 fe80:5b53:cdd9:a969:9e9c%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): {213.26.172.183, 88.226.154.206}
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 0f:1d:1b:54:9f:d0
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 55:1c:47:c8:e9:d2
}
Resolving Issues with Wired and Wireless Connectivity
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.
Effectively Addressing Problems on Apple macOS / OSX
Irrespective of whether you are using OSX/macOS versions such as 10.15.7, 11.3.7, or 12.0.7, 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 crucial, especially for teams that have adopted remote work and Work From Anywhere (WFA) practices.
Utilizing In-Built Scripts for Assistance
An extremely useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless-related settings to the CLI and can be configured to generate specific logs for troubleshooting. Furthermore, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only point-in-time information 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, for an interactive run (even though there is not much interaction), you can execute sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. If not run in the background, it should open Finder in the correct location, allowing you to navigate to /var/tmp or use Finder with Cmd+Shift+G to point Finder to the path. However, be cautious of large file sizes, around 300MB or more.
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