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. Moreover, this method does not offer any historical data, especially when dealing with past issues.
Navigating Through the World Wide Web
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.
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