How Do You Support Apple Internet
Understanding Internet Addressing System
When using the Internet, individuals may be assigned a Public IPv4 address such as 128.98.46.64 or an IPv6 address like 2000:343c:5bb2:d5de:f749:70d4:1a1c:7905. This information can be verified at https://test-ipv6.com/. However, for those who are not technically inclined, attempting to convey these addresses or even referring to MAC addresses like 10:c5:21:a1:75:cc can be prone to errors and can become convoluted. Furthermore, this approach does not provide historical data, particularly when past issues occurred.
Navigating the World Wide Web
In order to access a website such as https://lockman.io, it is necessary to initially contact a DNS server to translate the host portion (lockman) combined with the Top Level Domain (io) of the URL into an IP address, as in the case of 203.29.137.223. It is important to note that the computer and browser include specific details with every web request, such as Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
The Significance of Default Gateways
The default gateway is typically an address that is automatically configured through DHCP. A default gateway address such as 192.168.224.3 is assigned, although they typically conclude with .1 or .254 depending on the scope size. This is the location your computer forwards all its traffic to be routed onwards. For information pertaining to IPV6, a comprehensive guide can be found at how-to-fix-ipv6-connectivity/. To verify this on Mac or Linux, the following commands can be used:
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 192.168.224.3 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:fe85:56ff:c2f2:65ab%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): {133.251.86.11, 109.216.115.206}
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 10:c5:21:a1:75:cc
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 de:8e:60:fc:d7:e7
}
Resolving Issues with Wired and Wireless Connections
When transferring data to your router, you might be using a wired or wireless (Wi-Fi) medium at the physical and data layer.
Tips for Troubleshooting on Apple macOS / OSX
Irrespective of the version of OSX/macOS you are using, whether it’s 10.11.3, 11.3.8, or 12.0.9, there are numerous tools available for resolving issues. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes vital, especially for teams that have adopted remote work and Work From Anywhere (WFA) policies.
Embedded Scripts That Offer Assistance
An extremely useful tool on OSX/macOS is ‘sudo wdutil info’, which provides a dump of the current wireless settings to the CLI, and can also be configured to generate specific logs for troubleshooting purposes. Furthermore, the ‘sysdiagnose’ tool can be used to generate a wide range of logs, although much of it pertains to wireless settings at a specific point in time, similar to wdutil.
The command ‘sudo nohup /usr/bin/sysdiagnose -u &’ will run ‘sysdiagnose’ in the background and write logs to ‘/var/tmp/
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