When using the Internet, you are assigned a unique identifier such as 159.92.250.179
for IPv4 or 2000:6cb1:7750:4dff:dd7f:feb7:c086:725
for IPv6. You can verify this information on https://test-ipv6.com/. However, conveying and discussing these addresses, as well as MAC addresses like a5:c8:65:0b:f8:8d
, can be prone to errors and become complex. Moreover, it does not provide any historical data, especially for past issues.
To access a website such as https://bernier.name, your device initially communicates with a DNS server to convert the host portion (bernier) along with the Top Level Domain (name) of the URL into an IP address, such as 170.187.192.206
. Every web request from your computer and browser contains its type, for example: Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
Your default gateway is typically an automatically assigned address via DHCP. It assigns a default gateway like 10.231.157.91
(commonly ending in .1 or .254 based on the scope size), which serves as the point your computer uses to forward all its traffic. For IPv6
, a detailed guide on how-to-fix-ipv6-connectivity/ is available, and you can check it on Mac or Linux using:
netstat -rn -f inet | egrep -i "default|0/1|128.0/1"
0/1 172.18.12.193 UGScg utun3 default 10.231.157.91 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.
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:d5ab:73c9:ad15:5586%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.
To get a look at the low level DHCP configuration (Mac/Linux):
ipconfig getpacket en0
... domain_name_server (ip_mult): {156.92.23.141, 110.190.110.41} 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 a5:c8:65:0b:f8:8d 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 43:2d:6a:db:5b:61 }
When transmitting data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
No matter which version of OSX or macOS you are currently operating on - be it 10.13.5
, 11.5.5
, or 12.0.4
- there are several tools available for troubleshooting. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that are adopting a remote work and Work From Anywhere (WFA) approach.
One useful tool on OSX/macOS is the sudo wdutil info
command, which provides a dump to the CLI of the current wireless settings, and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose
tool can be used to generate a plethora of logs, though it is primarily point-in-time related to wireless operations, akin to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u &
in the background will write logs to /var/tmp/<blah>.tar.gz
for you. If you prefer to run it interactively, you can execute sudo /usr/bin/sysdiagnose
, which will display a privacy warning. When run in the foreground, it should open Finder in the correct location, or you can navigate to /var/tmp
. However, be cautious of the file sizes, which are approximately 300MB more or less.
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