How Do You Support Apple Internet Connection
Understanding Internet Addressing
When using the Internet, individuals may be assigned a Public IPv4 address, such as 255.84.105.53, or an IPv6 address, like 2000:5bf5:f36a:ad75:edea:91d1:e1ab:82c0. Verification of these addresses can be done through https://test-ipv6.com/. However, conveying these addresses to non-technical individuals or even referring to MAC addresses such as 63:1f:53:67:1c:be can be prone to errors and quickly becomes complex. It also lacks historical data, especially with past issues.
Navigating the Internet
When attempting to access a web page, like https://nikolaus.org, users initially connect to a DNS server to convert the host portion (nikolaus) and the Top Level Domain (org) of the URL to an IP address, such as 48.181.160.87. Computers and browsers disclose their type with all web requests, for example:
Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
Significance of Default Gateways
The default gateway is typically an automatically configured address through DHCP. Users receive a default gateway, such as 172.29.16.66 (usually ending in .1 or .254 based on the scope size), which is the point where the computer routes all its traffic. For IPv6, detailed instructions are available in the blog post how-to-fix-ipv6-connectivity/, and can be verified on Mac or Linux using the following code:
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 172.29.16.66 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 fe80:62f5:b35:691:51a9%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): {199.247.216.240, 125.165.225.19}
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 63:1f:53:67:1c:be
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 15:a0:ae:18:70:ef
}
Resolving Issues with Wired or Wireless Networks
When it comes to transmitting data to your router, you might be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
Regardless of whether your system is running OSX/macOS version 10.14.8, 11.0.5, or 12.1.6, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a continuous set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that have embraced remote work and the Work From Anywhere (WFA) approach.
Useful Built-in Scripts
One particularly useful tool for OSX/macOS is sudo wdutil info, which provides a dump of the current wireless settings to the CLI, and can also be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only related to wireless settings and is not continuously updated like wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & will execute it in the background and write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (although there isn’t much interaction), you can use sudo /usr/bin/sysdiagnose and it will display a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to locate the path. Just be mindful of the file sizes, which are approximately 300MB.
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