Support OSX Issues
The Functioning of Internet Addressing
When using the Internet, individuals are assigned with a unique Public IPv4 address, such as 105.101.196.202, or an IPv6 address like 2000:2d50:4968:23a9:ce08:86ad:e3f3:6584. It is possible to verify this information by visiting https://test-ipv6.com/. However, conveying these addresses, including the MAC addresses like e8:74:9b:7e:1a:b8, can be challenging for those with limited technical knowledge and may lead to errors. Moreover, no historical data is provided by this method, particularly when attempting to address past issues.
Navigating the Internet
Accessing a website, such as https://quitzon.name, initially involves a DNS server to convert the host portion (quitzon) and the Top Level Domain (name) of the URL into an IP address, for example, 193.243.201.5. When making web requests, your computer and browser sends along its specifications, including its type, for example: Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)
The Significance of Default Gateways
By default, the gateway address is automatically assigned using DHCP. Typically, a default gateway is received, such as 192.0.0.88 (usually ending in .1 or .254 depending on the scope size), where all computer traffic is routed. For IPv6, detailed instructions are available at how-to-fix-ipv6-connectivity/ and can be verified on Mac or Linux platforms using the following 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 192.0.0.88 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 fe80:4013:f3c9:76b8:e0da%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): {194.159.243.179, 39.219.84.195}
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 e8:74:9b:7e:1a:b8
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 6f:b7:9f:7f:3a:cd
}
Fixing Connectivity Issues for Wired and Wireless Networks
When it comes to transferring data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Solutions for Apple’s macOS / OSX
No matter which version of OSX/macOS you have - whether it’s 10.11.3, 11.3.3, or 12.0.2 - there are various tools available for troubleshooting connectivity issues. However, these manual actions and scripts don’t provide a set of correlated values over time. Automated remote troubleshooting becomes invaluable, especially for teams that prioritize remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
One useful tool in 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 wide range of logs (although much of it is only relevant to wireless settings, similar to wdutil).
Running sudo nohup /usr/bin/sysdiagnose -u & will execute it in the background and write logs to /var/tmp/<blah>.tar.gz for you. If you want to run it interactively, you can run sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. If not run in the background, it should open Finder in the correct location or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to go to the path. Keep in mind that the file sizes are around 300MB, give or take.
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