Check Mac Internet

Understanding Internet Protocol Addressing When using the Internet, you are assigned a Public IPv4 address such as 77.167.153.80 or an IPv6 address like 2000:7d51:beb5:6e04:3c24:9845:8e53:717e. These addresses can be verified at https://test-ipv6.com/. However, conveying these addresses to individuals who are not well-versed in technology, or even referencing MAC addresses like 96:30:98:80:64:e4, can be prone to error and can become complex quickly. Understanding Internet Protocol Addressing When using the Internet, you are assigned a Public IPv4 address such as 77.167.153.80 or an IPv6 address like 2000:7d51:beb5:6e04:3c24:9845:8e53:717e. These addresses can be verified at https://test-ipv6.com/. However, conveying these addresses to individuals who are not well-versed in technology, or even referencing MAC addresses like 96:30:98:80:64:e4, can be prone to error and can become complex quickly.

Understanding Internet Protocol Addressing

When using the Internet, you are assigned a Public IPv4 address such as 77.167.153.80 or an IPv6 address like 2000:7d51:beb5:6e04:3c24:9845:8e53:717e. These addresses can be verified at https://test-ipv6.com/. However, conveying these addresses to individuals who are not well-versed in technology, or even referencing MAC addresses like 96:30:98:80:64:e4, can be prone to error and can become complex quickly. Additionally, this does not provide any historical data, particularly for past issues.

When aiming to access a website, such as https://hilll.info, the first step is to connect to a DNS server, which translates the host portion (hilll) along with the Top Level Domain (info) of the URL into an IP address like 174.21.139.64. With every web request, your computer and browser transmit their type, 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

Normally, your default gateway is assigned as an automatically configured address via DHCP. This default gateway, such as 172.30.18.202 (usually ending in .1 or .254, based on the scope size), is where your computer sends all its traffic to be routed onwards. For IPv6, detailed guidance is available in our article how-to-fix-ipv6-connectivity/. However, on Mac or Linux systems, you can verify this by running:

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  172.30.18.202    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   9bab:a2b7:68d:52:fa77:f0ac:85c2:bf72%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): {142.31.31.191, 124.161.50.253}
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 96:30:98:80:64:e4
  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 91:cf:a8:3f:da:a4
}

Resolving Wired and Wireless Connection Issues

When it comes to transmitting data to your router, you might encounter connectivity issues at the physical and data layer, whether using a wired or wireless (Wi-Fi) medium.

Troubleshooting Tips for Apple macOS / OSX

Regardless of the version of OSX/macOS you are running, be it 10.11.3, 11.3.4, or 12.3.7, there are various tools available for troubleshooting. However, these tools may not provide a sequence of correlated values over time, especially for teams embracing remote work and Work From Anywhere (WFA).

Utilizing In-Built Scripts

A useful script on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI, and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although many are only relevant at a specific point in time, similar to wdutil.

Running sudo nohup /usr/bin/sysdiagnose -u & will execute it in the background and write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can execute 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 using Cmd+Shift+G in Finder. However, be cautious of the file sizes, which can be around 300MB.

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