How To Support OSX Connectivity

Understanding Internet Protocol Addressing When using the Internet, you are assigned either a Public IPv4 address, such as 205.45.76.54, or an IPv6 address, like 2000:c546:e000:c658:8826:3937:88fa:9b68. One way to verify this is by visiting https://test-ipv6.com/. However, explaining these addresses, or even mentioning MAC addresses like 6b:5f:96:5d:40:61, to those who are not tech-savvy can be prone to errors and quickly become complex. Understanding Internet Protocol Addressing When using the Internet, you are assigned either a Public IPv4 address, such as 205.45.76.54, or an IPv6 address, like 2000:c546:e000:c658:8826:3937:88fa:9b68. One way to verify this is by visiting https://test-ipv6.com/. However, explaining these addresses, or even mentioning MAC addresses like 6b:5f:96:5d:40:61, to those who are not tech-savvy can be prone to errors and quickly become complex.

Understanding Internet Protocol Addressing

When using the Internet, you are assigned either a Public IPv4 address, such as 205.45.76.54, or an IPv6 address, like 2000:c546:e000:c658:8826:3937:88fa:9b68. One way to verify this is by visiting https://test-ipv6.com/. However, explaining these addresses, or even mentioning MAC addresses like 6b:5f:96:5d:40:61, to those who are not tech-savvy can be prone to errors and quickly become complex. Moreover, this method does not offer any historical data, especially when dealing with past issues.

In order to access a website, such as https://abbott.biz, the initial step involves reaching out to a DNS server to convert the host portion (abbott) along with the Top Level Domain (biz) of the URL into an IP address, like 117.104.23.30. Your computer and browser also convey their information with every web request, for example: `
``Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0```

Understanding the Significance of Default Gateways

Usually, your default gateway is an automatically configured address via DHCP. It is assigned as a default gateway, such as 192.168.231.106 (although they usually end in .1 or .254 depending on the scope size), and all traffic from your computer is routed through this location. For more in-depth information on IPv6, visit our blog post on how-to-fix-ipv6-connectivity/. To check this on Mac or Linux, you can use:

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  192.168.231.106    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   fe80:3567:b2c1:194a:c180%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): {190.220.51.66, 241.5.15.94}
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 6b:5f:96:5d:40:61
  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 1d:87:c0:94:50:5f
}

Fixing Connectivity Issues for Wired and Wireless Networks

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

Troubleshooting Tips for Apple macOS / OSX

Regardless of whether you are using OSX/macOS version 10.15.7, 11.0.9, or 12.1.9, there are various troubleshooting tools available. However, these tools do not provide a series of correlated values over time, making remote troubleshooting crucial, especially for remote work and Work From Anywhere (WFA) teams.

Helpful Built-in Scripts

On OSX/macOS, the “sudo wdutil info” command can be used to obtain current wireless settings and generate specific logs for troubleshooting. Additionally, the “sysdiagnose” tool provides a wide range of logs related to wireless, and can be run in the background using the command “sudo nohup /usr/bin/sysdiagnose -u &”, or interactively by using “sudo /usr/bin/sysdiagnose”. However, users should be aware of the large file sizes generated by this tool, usually around 300MB.

Possibly Helpful Videos

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