How Do You Support MacOS Issues

Understanding Network Addressing

When using the internet, you will be assigned a unique Public IPv4 address such as 9.140.61.171 or an IPv6 address like 2000:23b1:162:e249:8f74:aa1:5c5:64e3. These addresses can be verified on https://test-ipv6.com/. However, explaining or sharing these addresses, along with MAC addresses like fc:c4:6b:53:48:7e, can be prone to errors and complexity, especially for those without a technical background. Furthermore, these addresses do not provide any historical data, particularly regarding past issues.

Navigating the Internet

Accessing a website, such as https://williamson.name, involves the initial contact with a DNS server in order to convert the host portion (williamson) combined with the Top Level Domain (name) of the URL into an IP address, such as 64.58.158.216. When making web requests, your computer and browser also transmit specific type details, 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

The default gateway is typically an automatically assigned address through DHCP. This address, such as 192.0.0.22 (although usually ending in .1 or .254 depending on the scope size), is where your computer forwards all of its traffic to be routed onward. To further explore IPv6 connectivity issues, visit our in-depth analysis at how-to-fix-ipv6-connectivity/ or utilize the provided commands for 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  192.0.0.22    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   fe80:22c2:a5de:7005:d4ea%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): {243.199.53.89, 171.131.34.175}
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 fc:c4:6b:53:48:7e
  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 2f:59:ea:d6:13:af
}

Resolving Connectivity Issues for Wired and Wireless Networks

When it comes to transmitting data to your router, you may be utilizing either a wired or a wireless (Wi-Fi) medium at the physical and data layer.

Troubleshooting Tips for Apple’s macOS / OSX

Regardless of whether you are running OSX/macOS version 10.14.4, 11.5.2, or 12.3.4, there are various troubleshooting tools available. However, these manual methods and scripts do not provide a set of interconnected values over time. This is where automated remote troubleshooting becomes particularly valuable, especially for teams that have adopted remote work and a Work From Anywhere (WFA) approach.

Embedded Utilities for Assistance

An extremely useful tool on OSX/macOS is the sudo wdutil info command, 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 offers a more comprehensive option for generating a wide range of logs, although much of the information is only relevant at a specific point in time, similar to wdutil.

Runningsudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs at /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (although there is minimal interaction), you can use
sudo /usr/bin/sysdiagnose which will display a privacy warning. If 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 direct Finder to the path. Keep in mind that the file sizes range from about 300MB or so.

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Table 1.0 - Video Help