Who's that MAC?

Got a strange MAC address connecting to your private Wifi network? 

Find out what kind of device it is using https://maclookup.app/.

The underlying database is regularly updated using IEEE and Wireshark data.

MAC addresses are 48 bits (6 bytes)  long, the first 24 bits are known as the OUI (assigned by the IEEE Registration Authority to the vendor/manufacturer) and the last 24 bits are assigned by the manufacturer. 

Basics of NAT

NAT refers to Network Address Translation.

NAT allows multiple devices in a private network to access the Internet using a single, public IP address. This results in a number of benefits, one being conservation of IP addresses (relevant for IPv4) and hides internal systems for added security.

Routers perform NAT to relay information between connected devices and the public Internet.

What is iptables?

iptables is a command in Linux for maintenance of IP packet filter rules in the Linux kernel. It enables configuration of security policies, control of incoming and outgoing traffic and network address translation (NAT).

iptables is not available in cmd.exe but it is available in WSL2.

A Windows Joe may therefore not have much exposure to iptables in day-to-day administration but should nevertheless have a good working knowledge of NAT and its terminology, as it's a universal networking concept.

Convert a Word Doc into A Presentation (Ad Hoc)

A Word doc can be brought to life as a presentation quite easily.

Go to View in the Ribbon.

Under Page Movement select Side to Side (this changes the display so you can see the flow of the document - it is not strictly needed - but helpful to start visualising flow).

Now under Views, you will most likely see "Print Layout" selected.  Select instead "Read Layout". 

This will start a presentation-mode document presentation.

(There is also a third layout; called Web Layout, which effectively turns your document into a web page - albeit a very messy one in all probability).

The Weird World of OCSP Revocation Checks (Certificate Status)

OCSP, or Online Certificate Status Protocol, enables real-time verification (for clients like web browsers) of digital certificate validity (rather than use downloaded lists of revoked certificates, a la CRLs, or certificate revocation lists). 

It reduces overhead in validation (could be useful in real-time use cases e.g. transaction processing).

Statuses can be "good", "revoked" or "unknown".

Certificate Authorities (CAs) are mandated to track certificates they revoke.

whois under the hood (just basic TCP)

The whois protocol is a very basic TCP-based query-response protocol that gives information on domain names. Unfortunately, it is not installed by default in cmd.exe but is available in WSL. 

It works by opening a TCP connection (SYN, SYN+ACK), query sent, response sent and a close (FIN, FIN)- very basic indeed. It has no mechanism for indicating character set used, and there has been no effort to support internationalisation in that respect. Historically the predominant encoding used has been US-ASCII.

It has no security provisions. Mechanisms for access control, integrity and confidentiality are excluded.

rdap is a modern alternative to whois. RDAP stands for Registration Data Access Protocol.

Content Credentials

Want to know if something was generated by generative AI?  

Maybe try Content Credentials, a scheme supported by the Coalition for Content Provenance and Authenticity (C2PA) with support from Abode, Microsoft, Google, OpenAI and Sony.

Adobe's Creative Cloud website details their support for it here.