When using the Internet, individuals may be assigned a Public IPv4 address, such as 212.124.27.152
, or an IPv6 address, like 2000:ee4:1563:fac8:8a37:32a6:f6f9:263b
. To verify this, visit https://test-ipv6.com/. However, conveying these addresses, as well as MAC addresses like c6:4d:34:d4:ec:e4
, can be error-prone and complex for those who are not tech-savvy. Moreover, it does not provide historical data, especially regarding past issues.
When attempting to access a webpage, such as https://witting.org, the first step is to access a DNS server to convert the host portion (witting) and the Top Level Domain (org) of the URL into an IP address, such as 118.159.242.110
. Each web request from your computer and browser also includes its type, for example: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A
In most cases, the default gateway is an address that is automatically configured via DHCP. This default gateway, such as 10.34.31.237
(usually ending in .1 or .254 based on the scope size), is where a computer sends all its traffic to be routed further. For a detailed guide on configuring it for IPv6
, refer to how-to-fix-ipv6-connectivity/, or check it on Mac or Linux using the following command.
netstat -rn -f inet | egrep -i "default|0/1|128.0/1"
0/1 172.18.12.193 UGScg utun3 default 10.34.31.237 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 fe80:4d2a:8401:9189:e8bf%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): {137.178.221.146, 216.177.128.48} 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 c6:4d:34:d4:ec:e4 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 e1:56:71:02:9f:38 }
When it comes to sending data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Regardless of which version of OSX/macOS you are using, whether it’s 10.11.8
, 11.6.4
, or 12.1.5
, there are several tools available for troubleshooting. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes valuable, particularly for teams that practice remote work and Work From Anywhere (WFA).
On OSX/macOS, a useful tool is sudo wdutil info
, which dumps current wireless related settings to the CLI and can also generate specific logs for troubleshooting. Furthermore, the sysdiagnose
tool can be used to generate a wide range of logs, although much of it is only relevant to the wireless issues, similar to wdutil.
To run sudo nohup /usr/bin/sysdiagnose -u &
in the background and have it write logs to /var/tmp/<blah>.tar.gz
. For an interactive option (even though there is minimal interaction), you can run sudo /usr/bin/sysdiagnose
and it will prompt a privacy warning. If not run in the background, it should open Finder in the correct location. Otherwise, you can navigate to /var/tmp
or use Finder with Cmd+Shift+G to locate the path. Keep in mind that the file sizes are around 300MB more or less.
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