When using the Internet, individuals may be assigned a Public IPv4 address, such as 87.71.36.20
, or an IPv6 address, like 2000:d4d4:185d:a4af:63fd:b231:965e:cdd3
. This information can be verified at https://test-ipv6.com/. However, for those unfamiliar with technical terminology, conveying these addresses, or even referencing MAC addresses like 4a:cd:a7:18:4e:f7
, can be prone to errors and becomes complex. Additionally, it does not provide any historical data, particularly regarding past issues.
When attempting to visit a web page, such as https://orn.net, an initial step involves accessing a DNS server to translate the host portion (orn) combined with the Top Level Domain (net) of the URL to an IP address, like 92.198.122.220
. Additionally, the computer and browser transmit their types with all web requests, 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
Typically, a default gateway is an automatically configured address received via DHCP. This default gateway, such as 10.78.15.152
(commonly ending in .1 or .254 based on the scope size), is where a computer sends all traffic to be routed onwards. For IPv6
, comprehensive information is available in the article how-to-fix-ipv6-connectivity/. Users can also verify this information 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 10.78.15.152 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:ff22:8e26:73c0:9951%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): {178.33.123.237, 39.109.61.210} 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 4a:cd:a7:18:4e:f7 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 7f:60:6a:1a:bb:ca }
When transmitting 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.
Regardless of the version of OSX/macOS you are using, whether it’s 10.15.9
, 11.1.5
, or 12.1.5
, there are several troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes invaluable, particularly for teams that embrace remote work and Work From Anywhere (WFA).
A useful tool on OSX/macOS is the sudo wdutil info
, which provides a dump of current wireless settings to the CLI, and can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose
tool can be used to generate a variety of logs, although much of it is only related to wireless settings at a particular point in time, similar to wdutil.
To run sysdiagnose
in the background and generate logs in /var/tmp/<blah>.tar.gz
, you can use the command sudo nohup /usr/bin/sysdiagnose -u &
. If you prefer to run it interactively, you can use the command sudo /usr/bin/sysdiagnose
, which will give a privacy warning. When running it in the foreground, it will open Finder in the correct location, or you can navigate to /var/tmp
or use Finder with Cmd+Shift+G to specify the path. Keep in mind that the file sizes are approximately 300MB.
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