Fix Mcs Router Issues
Understanding Internet Addressing
When using the Internet, you are given a Public IPv4 address such as 8.232.55.23 or an IPv6 address like 2000:be08:bb77:d83d:d89a:2d7:a08c:dd34. The website https://test-ipv6.com/ allows you to verify these addresses. Communicating these addresses and MAC addresses like 56:7a:ed:b9:d8:67 can be challenging, especially for those who are not tech-savvy. Furthermore, it does not provide historical data, which is essential for resolving past issues.
Navigating the World Wide Web
In order to access a website such as https://bergnaum-murazik.org, your computer first contacts a DNS server to convert the host portion (bergnaum-murazik) along with the Top Level Domain (org) of the URL to an IP address like 162.54.142.181. Additionally, your computer and browser send their type with all web requests, for example:Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A
The Significance of Default Gateways
Your default gateway is typically an address automatically configured via DHCP, such as 172.31.9.25 (usually ending in .1 or .254 based on the scope size). This is where your computer directs all its traffic to be further routed. For IPv6, a detailed explanation is available in how-to-fix-ipv6-connectivity/. Additionally, you can verify this on Mac or Linux with:
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 172.31.9.25 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 fe80:2409:961:fc51:fd60%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): {17.181.161.13, 83.88.66.230}
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 56:7a:ed:b9:d8:67
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 d9:a2:7c:a4:1d:3b
}
Solutions for Resolving Wired and Wireless Connectivity Issues
When it comes to transferring data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Actions to Take for Apple macOS / OSX Users
Regardless of whether you are using OSX/macOS versions such as 10.13.1, 11.0.2, or 12.1.9, there are numerous troubleshooting tools available. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes essential, especially for teams that embrace remote work and Work From Anywhere (WFA).
Useful Built-in Tools That Can Aid in Troubleshooting
In OSX/macOS, the sudo wdutil info tool is extremely helpful as it provides a dump of current wireless related 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 is only relevant to wireless settings at a specific point in time, similar to wdutil.
To run sudo nohup /usr/bin/sysdiagnose -u & in the background and write logs to /var/tmp/<blah>.tar.gz, or to run it interactively, users can execute 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 users can navigate to /var/tmp using Finder with the Cmd+Shift+G command. However, users should be mindful of the file sizes, which can be around 300MB or more.
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