How Do You Check Mac IP Settings
Understanding Internet Protocol Addresses
When connecting to the Internet, you are assigned either a Public IPv4 address, such as 25.174.154.171, or an IPv6 address like 2000:28c3:e092:8192:2f32:68d1:ef75:d521. These can be verified on https://test-ipv6.com/ However, conveying these addresses, and even MAC addresses like 4a:b4:f3:c5:1d:db, to those who are not technologically-versed can be challenging and prone to errors. It also lacks historical data.
Navigating the World Wide Web
Accessing a website such as https://zemlak-stroman.io involves the use of a DNS server to translate the host part (zemlak-stroman) combined with the Top Level Domain (io) of the URL into an IP address like 28.120.29.69. Every web request from your computer and browser contains information about its type. For example: Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
Significance of Default Gateways
Default gateways are typically automatically configured addresses via DHCP. A default gateway, such as 192.168.149.136 (usually ending in .1 or .254 depending on the scope size), is where your computer directs all its traffic to be routed onwards. For IPv6, we have a detailed explanation on how-to-fix-ipv6-connectivity/. You can also check on Mac or Linux using:
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 192.168.149.136 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 fe80:1842:7344:3b41:9ace%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): {244.99.94.195, 39.21.149.105}
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:b4:f3:c5:1d:db
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 60:44:5e:30:2b:ff
}
Fixing Network Connectivity Issues
When it comes to transmitting data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Methods for Apple macOS / OSX
No matter the version of OSX/macOS you are currently using - whether it’s 10.12.1, 11.1.4, or 12.3.8, there are various 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 essential, especially for teams that are embracing remote work and Work From Anywhere (WFA).
Useful Built-in Tools
One extremely useful tool for OSX/macOS is the sudo wdutil info, which provides a dump to the CLI of current wireless related settings and can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only relevant to wireless issues, 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 running it interactively, you can use sudo /usr/bin/sysdiagnose, which will prompt 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 with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB or less.
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