When using the Internet, one can have a Public IPv4 address, such as 234.0.228.61
, or an IPv6 address, like 2000:fd4f:c2eb:358f:65f2:5455:2878:41c7
. These can be verified at https://test-ipv6.com/. However, presenting these addresses, or MAC addresses like d3:63:3c:7c:cc:b8
to those without technical expertise can be prone to errors and become complex. Moreover, this fails to provide any historical data, particularly from past issues.
To access a webpage such as https://hane-considine.net, you first reach out to a DNS server to convert the host part (hane-considine) combined with the Top Level Domain (net) of the URL into an IP address, like 255.98.215.180
. Your computer and browser indicate their type with all web requests, such as: Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)
Commonly, your default gateway is an automatically configured address via DHCP. Usually ending in .1 or .254 depending upon the scope size, you receive a default gateway, such as 192.168.97.76
, and this is where your computer forwards all its traffic for routing. For IPv6
, we offer an in-depth analysis on how-to-fix-ipv6-connectivity/, but you can verify on Mac or Linux with:
netstat -rn -f inet | egrep -i "default|0/1|128.0/1"
0/1 172.18.12.193 UGScg utun3 default 192.168.97.76 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 fe80:5a24:d302:840b:af7c%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): {139.17.89.156, 216.164.230.122} 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 d3:63:3c:7c:cc:b8 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 a3:df:ed:fa:eb:8c }
When it comes to sending data at the physical and data layer, you have the option of using either a wired or wireless (Wi-Fi) medium to transmit data to your router.
Regardless of the version of OSX/macOS you are using, whether it’s 10.13.3
, 11.1.1
, or 12.0.2
, there are various 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 valuable, especially for teams that embrace remote work and Work From Anywhere (WFA).
One useful tool on OSX/macOS is the sudo wdutil info
command, which provides a dump of current wireless related settings to the CLI and can be configured to generate specific logs for troubleshooting. Additionally, the more comprehensive sysdiagnose
tool can be used to generate a wide range of logs, although much of it is only relevant to wireless at a specific point in time, similar 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 (though there isn’t much interaction), you can run 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
manually, or use Finder with Cmd+Shift+G to navigate to the path. Just be aware that the file sizes are around 300MB, more or less.
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