How Do You Understand Mac Internet

Understanding Internet Addressing When connecting to the internet, you are assigned a unique public IPv4 or IPv6 address, such as 232.20.98.18 or 2000:b090:ab2:2bbf:b666:6ae3:344c:293b. Ensure your address is accurate by checking on https://test-ipv6.com/. For those unfamiliar with technical details, conveying these addresses, including MAC addresses like 1c:1f:03:82:63:f0, can be complicated and prone to errors, especially without access to historical data. Understanding Internet Addressing When connecting to the internet, you are assigned a unique public IPv4 or IPv6 address, such as 232.20.98.18 or 2000:b090:ab2:2bbf:b666:6ae3:344c:293b. Ensure your address is accurate by checking on https://test-ipv6.com/. For those unfamiliar with technical details, conveying these addresses, including MAC addresses like 1c:1f:03:82:63:f0, can be complicated and prone to errors, especially without access to historical data.

Understanding Internet Addressing

When connecting to the internet, you are assigned a unique public IPv4 or IPv6 address, such as 232.20.98.18 or 2000:b090:ab2:2bbf:b666:6ae3:344c:293b. Ensure your address is accurate by checking on https://test-ipv6.com/. For those unfamiliar with technical details, conveying these addresses, including MAC addresses like 1c:1f:03:82:63:f0, can be complicated and prone to errors, especially without access to historical data.

When accessing a webpage like https://macejkovic-kerluke.info, your computer communicates with a DNS server to translate the host portion (macejkovic-kerluke) combined with the Top Level Domain (info) to an IP address like 36.229.137.46. Additionally, your computer and browser send its type with every web request, 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

Your default gateway is typically an automatically configured address via DHCP, such as 172.17.41.102, where your computer sends all its traffic to be routed onwards. For IPv6, detailed information on how to check on Mac or Linux is available at 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  172.17.41.102    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:ec9f:f9d9:1910:f2c8%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): {119.121.174.208, 88.221.41.127}
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 1c:1f:03:82:63:f0
  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 43:82:3a:6d:39:25
}

Resolve Issues with Wired or Wireless Connections

Whether you are using a physical wired connection or a wireless (Wi-Fi) medium at the data layer to transmit data to your router, troubleshooting can help resolve any issues.

Troubleshooting Tips for Apple macOS / OSX Users

No matter which version of OSX/macOS you are currently using, whether it’s 10.15.8, 11.3.9, or 12.0.7, there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting comes into play, particularly for teams that are embracing remote work and Work From Anywhere (WFA).

Useful Built-in Tools for Troubleshooting

One useful tool for OSX/macOS users is the sudo wdutil info command, which provides a dump of current wireless settings to the CLI and can be configured to generate specific troubleshooting logs. Another comprehensive tool is the sysdiagnose tool, which can generate a wide range of logs, although much of it pertains to wireless settings only, similar to wdutil.

To run the sysdiagnose tool in the background and generate logs in /var/tmp/<blah>.tar.gz, you can use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can use the command sudo /usr/bin/sysdiagnose, although it will display a privacy warning. When not run in the background, it will open Finder in the correct location for you to access the logs, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB.

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