How Can I Fix MacOS Internet
Understanding Internet Address Allocation
When connecting to the Internet, users are typically assigned a Public IPv4 address such as 31.177.80.46 or an IPv6 address like 2000:29ec:5010:bd50:189d:9abe:3d4e:aec4. A tool like https://test-ipv6.com/ can be used to verify these addresses. However, conveying these complex addresses, or even the MAC address 13:88:57:37:29:fa, to non-technical individuals can be prone to errors and quickly become confusing. Moreover, this method does not offer any historical data, especially relating to past issues.
Understanding Web Connectivity
Accessing a web page, such as https://predovic.io, initially involves querying a DNS server to translate the URL’s host portion (predovic) and its Top Level Domain (io) to an IP address like 114.26.34.173. When making web requests, the computer and browser transmit specific information, such as Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16.
Significance of Default Gateways
The default gateway is typically assigned automatically through DHCP and often ends with .1 or .254, depending on the scope size. This is the point to which all traffic from a computer is sent for routing. For IPv6 connectivity, detailed instructions can be found in our blog post how-to-fix-ipv6-connectivity/. On Mac or Linux systems, this can be verified using the following command:
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 172.20.135.147 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 fe80:4bf0:3c2:119f:ade9%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): {182.198.163.33, 17.84.174.148}
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 13:88:57:37:29:fa
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 f0:d4:4f:ec:25:d8
}
Solutions for Wired and Wireless Connectivity Issues
When it comes to transmitting data to your router, you may be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Resolving Connectivity Problems on Apple macOS / OSX
Regardless of whether you are using OSX/macOS versions such as 10.14.8, 11.6.2, or 12.0.8, there are various troubleshooting tools available. However, these tools do not provide a set of correlated values over time, making it difficult to diagnose issues. This is where automated remote troubleshooting becomes invaluable, especially for teams that are embracing remote work and the Work From Anywhere (WFA) trend.
Utilizing Built-in Scripts for Assistance
On OSX/macOS, the sudo wdutil info tool is extremely helpful as it provides a dump of current wireless settings to the CLI and can be configured to generate specific troubleshooting logs. Additionally, the sysdiagnose tool offers a more comprehensive solution, generating a wide range of logs, although many of these are only related to wireless settings and are not time-bound like wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in /var/tmp/<blah>.tar.gz. For an interactive experience (although there is minimal interaction), you can run sudo /usr/bin/sysdiagnose with 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 files, which are typically around 300MB in size.
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