When using the Internet, individuals may be assigned a Public IPv4 address, such as 81.128.174.213
, or an IPv6 address, like 2000:f85e:4e14:9602:20b9:6a06:9f8:85af
. This information can be verified through https://test-ipv6.com/. However, conveying and discussing these complex addresses, and even mentioning MAC addresses like 11:2d:dd:29:63:97
, can be prone to errors and quickly become convoluted. Furthermore, this does not provide any historical data, particularly relating to past issues.
In order to access a website, such as https://waelchi.com, the initial step involves connecting to a DNS server to convert the host portion (waelchi) combined with the Top Level Domain (com) of the URL into an IP address, such as 45.93.47.222
. When making web requests, your computer and browser actually send its type, for example, Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Typically, your default gateway is an automatically configured address obtained through DHCP. This default gateway, such as 192.0.0.105
(usually ending with .1 or .254 based on the scope size), is where your computer directs all its traffic to be routed onwards. For IPv6
, a detailed explanation can be found at how-to-fix-ipv6-connectivity/. However, on Mac or Linux, you can check using the following command:
command prompt
netstat -rn -f inet | egrep -i "default|0/1|128.0/1"
0/1 172.18.12.193 UGScg utun3 default 192.0.0.105 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 fe80:65ab:ef73:7f60:f0b6%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): {178.248.163.28, 213.252.84.170} 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 11:2d:dd:29:63:97 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 4b:67:12:ea:e7:30 }
When it comes to transmitting data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Regardless of whether you are using OSX/macOS version 10.15.3
, 11.4.6
, or 12.0.3
, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes essential, particularly for teams that embrace remote work and Work From Anywhere (WFA).
The command sudo wdutil info
is a valuable tool on OSX/macOS as it provides a dump of current wireless settings to the CLI, and it can also be configured to generate specific logs for troubleshooting. In addition, the sysdiagnose
tool is more comprehensive and can be used to generate a wide range of logs, although many of them are only relevant to the wireless network at a specific moment in time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u &
in the background will generate logs in /var/tmp/<blah>.tar.gz
for you. If you prefer to run it interactively (even though there is minimal interaction), you can executesudo /usr/bin/sysdiagnose
, which 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 Finder or use Cmd+Shift+G in Finder to navigate to the path. Just keep in mind that the file sizes are approximately 300MB.
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