How Can I Check Mac Internet
Understanding Internet Addressing Systems
When using the Internet, you are assigned a Public IPv4 address, such as 45.111.56.111, or an IPv6 address, like 2000:1973:7f8:7e86:5f5b:4537:dc32:28d2. To verify this information, visit https://test-ipv6.com/. However, translating and communicating these addresses, or MAC addresses like 9c:35:df:44:fc:85, can become error-prone and complex, especially for those who are not tech-savvy. Furthermore, it lacks the capability to provide historical data, particularly when addressing past issues.
Navigating Online Content
When trying to access a webpage, such as https://rau-huels.co, your first step is to connect to a DNS server that translates the host portion (rau-huels) combined with the URL’s Top Level Domain (co) into an IP address, such as 177.160.116.10. Additionally, your computer and browser send their type with every web request, as shown: Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)
Significance of Default Gateways
The default gateway, typically an automatically configured address via DHCP, is the point to which your computer sends all its traffic to be routed onwards. You usually receive a default gateway like 192.0.0.98 (often ending in .1 or .254 depending on the scope size). For IPv6, refer to our comprehensive guide on how-to-fix-ipv6-connectivity/. Additionally, on Mac or Linux, you can verify this information by running the command:
IPv4 Routes and the Host IPv4 Route Table (inc. VPN)
netstat -rn -f inet | egrep -i "default|0/1|128.0/1"
0/1 172.18.12.193 UGScg utun3 default 192.0.0.98 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.
IPv6 Routes and the Host IPv6 Route Table (inc. VPN)
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 fe80:7858:758e:2446:8478%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.
Debugging DHCP for both IPv4 and IPv6
To get a look at the low level DHCP configuration (Mac/Linux):
ipconfig getpacket en0
...
domain_name_server (ip_mult): {187.198.76.74, 216.42.232.252}
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 9c:35:df:44:fc:85
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 7d:4c:b7:17:45:ca
}
Resolving Connectivity Issues for Wired and Wireless Networks
When it comes to transferring data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Solutions for Apple macOS / OSX
Regardless of whether you are running OSX/macOS versions such as 10.11.7, 11.4.2, or 12.0.3, there are various tools available for troubleshooting. However, these tools do not provide a set of correlated values over time, which is where automated remote troubleshooting becomes essential, particularly for teams that adopt remote work and Work From Anywhere (WFA) practices.
Integrated Scripts for Assistance
A useful tool on OSX/macOS is the sudo wdutil info, which displays current wireless settings and can be configured to generate specific logs for troubleshooting. Alternatively, the more comprehensive sysdiagnose tool can be used to generate an array of logs, although much of it is only relevant to wireless settings, similar to wdutil.
To run sysdiagnose in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. For an interactive run, you can execute the command sudo /usr/bin/sysdiagnose and it will produce a privacy warning. When not run in the background, it should open Finder at the appropriate location, otherwise you can navigate to /var/tmp using Finder or the shortcut Cmd+Shift+G. Keep in mind that the file sizes can vary around 300MB.
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