How Do You Fix Apple Internet
The Fundamentals of Internet Addressing
When utilizing the Internet, individuals can receive a Public IPv4 address, such as 126.151.107.32, or an IPv6 address, like 2000:968e:f73b:8727:d23c:2c43:9e90:d3e2. This information can be verified by visiting https://test-ipv6.com/. However, describing and conveying these addresses to those who are not technologically inclined, or even mentioning MAC addresses like 92:9a:cf:93:43:5a, can quickly become convoluted and prone to errors. Furthermore, this data does not offer any historical insights, particularly during past incidents.
Navigating the Internet
Accessing a webpage like https://turcotte.co first involves connecting to a DNS server to convert the host portion (turcotte) combined with the Top Level Domain (co) of the URL into an IP address, such as 234.142.167.81. Every time your computer and browser make a web request, they also transmit their type, such as Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36.
Understanding the Significance of Default Gateways
Typically, your default gateway is an address that auto-configures through DHCP. This gateway, such as 172.23.42.136 (with common endings of .1 or .254, depending on the scope size), is where your computer directs all its traffic for routing purposes. Instructions for checking on Mac or Linux are detailed in a comprehensive guide on how-to-fix-ipv6-connectivity/.
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 172.23.42.136 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 2549:3669:c3:6c79:78de:d88d:38a5:a84c%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): {106.244.177.199, 201.221.198.221}
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 92:9a:cf:93:43:5a
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 e7:ea:5b:e6:07:19
}
Diagnosing Connectivity Issues in Wired and Wireless Networks
When it comes to sending data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX Users
Regardless of whether you are running 10.15.1, 11.5.2, or 12.3.8, there are various tools available for troubleshooting connectivity issues. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes crucial, particularly for teams that have adopted remote work and Work From Anywhere (WFA) policies.
Useful Built-in Scripts
One useful tool on OSX/macOS for troubleshooting 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 purposes. Additionally, the sysdiagnose tool can be used to generate a comprehensive set of logs (though some 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 for you. If you prefer to run it interactively, you can run sudo /usr/bin/sysdiagnose, which will give a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. However, keep in mind that the file sizes can be around 300MB.
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