How Can I Support Mac Issues
The Fundamentals of Internet Addressing Systems
The Internet operates using different types of IP addresses, such as the Public IPv4 address 251.187.205.4 and the IPv6 address 2000:4e9:77f6:b966:170d:2ead:1457:e275. To verify these addresses, you can visit https://test-ipv6.com/. However, explaining and handling these addresses, including MAC addresses like 7a:dc:f8:79:41:ce, can be prone to errors and become complex. Moreover, this method does not provide historical data, especially for past issues.
Navigating the World Wide Web
When accessing a website, such as https://kub-oconnell.com, your computer first contacts a DNS server to convert the host portion (kub-oconnell) and the Top Level Domain (com) of the URL into an IP address, such as 219.238.23.121. Additionally, the computer and browser send their types 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)
Understanding the Significance of Default Gateways
The default gateway is usually an automatically configured address through DHCP. For example, you may receive a default gateway such as 172.30.25.57 (although they typically end in .1 or .254 based on the scope size), and this is the point where your computer forwards all its traffic to be routed further. For IPv6, a detailed analysis can be found at how-to-fix-ipv6-connectivity/, but 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 172.30.25.57 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 fe80:9b82:1aac:855f:63f5%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): {109.123.97.151, 89.144.158.175}
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 7a:dc:f8:79:41:ce
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 2d:38:17:94:be:5b
}
Fixing Connectivity Issues for Wired and Wireless Networks
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 Tips for Apple’s macOS / OSX Operating Systems
Regardless of whether you are running OSX/macOS versions such as 10.11.6, 11.1.5, or 12.3.8, there is a variety of troubleshooting tools available. However, these tools do not provide a set of correlated values over time, which makes automated remote troubleshooting particularly valuable, especially for teams that embrace remote work and Work From Anywhere (WFA).
Leveraging Built-in Scripts for Assistance
One extremely useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of the current wireless settings in the command line interface (CLI). This can also be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool offers a more comprehensive approach, generating a wide range of logs, albeit mainly point-in-time data in relation to wireless, 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 &. If you prefer to run it interactively, you can execute sudo /usr/bin/sysdiagnose while keeping in mind the large file sizes of about 300MB or more. 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.
Possibly Helpful Videos
P.S. Tips For Remote Network and Client Support
Digital work requires reliable connectivity. Whether for low latency or regular data streams, Wi-Fi, DNS, and network issues cause teams to lose time and productivity. Even worse is when support teams waste time trying to recreate and isolate issues! See how PanSift saves time, money, and frustration on all sides with instant remote troubleshooting 🏠🏝🛰.
