标签：#networking

Every deploy makes a promise about the network: "this box only exposes SSH and HTTPS," "the database is never reachable from outside the app tier." Nmap is how you turn that promise into a test that either passes or fails. Nobody has to take the security group's word for it. One rule before anything else: only scan systems you own or are explicitly authorized to assess. Point Nmap at a lab, a VM you control, or your own infrastructure. This is authorized infrastructure validation — a defensive check on exposure you're responsible for, not "hacking." Start with what's actually listening The most basic useful run is a host scan: nmap 192.168.56.10 This does host discovery and a default TCP scan of the common ports. The output lists each port as open , closed , or filtered . open means something accepted the connection. filtered usually means a firewall or security group silently dropped the packet — which is exactly the signal you want when validating that a rule is doing its job. If you expected a wall of filtered and instead see open , that's your finding. When you already know what should be exposed, scan for exactly that and nothing else: nmap -p 22,80,443 host Narrowing to the declared ports keeps the scan fast and the output readable. The question you're answering isn't "what's out there" — it's "does observed reality match what I declared?" Confirm what's really on the port An open port tells you a socket is listening. It does not tell you what . For that, add version detection: nmap -sV -p 22,80,443 host -sV probes each open port and reports the service and, when it can, the version banner. This matters because ports lie. A service you assumed was nginx on 443 might be something a teammate stood up last week. Read the SERVICE and VERSION columns and ask: is this the thing I expected, at the version I expected? A mismatch here is often the first sign of drift or a forgotten container. A methodology, not just commands Running Nmap ad hoc gives you trivia. Runnin

When someone says "Bitcoin has over 15,000 nodes worldwide," they mean 15,000+ independent computers are each running Bitcoin software and each maintaining their own full copy of the blockchain. No server owns the truth. Every node checks it for itself. That single fact — every node independently verifies every transaction and block against protocol rules — is the reason blockchains don't need a central authority. If one node tries to cheat, the rest simply ignore it. There's no admin account to compromise because there's no admin. Not All Nodes Do the Same Job Full Node Downloads and stores the entire blockchain, every block since genesis, and independently validates everything against consensus rules. Highest security ~500 GB for Bitcoin ~1 TB for Ethereum This is the backbone of network security. A full node doesn't trust anyone's summary of the chain; it recomputes validity itself. Light Node (SPV) Stores only block headers, not full transaction data. Uses Merkle proofs and relies on full nodes to verify transactions. Low storage, ~50 MB Trusts full nodes for verification What most mobile wallets run Mining/Validator Node A full node that also participates in block creation. Miners (Proof of Work) solve computational puzzles; validators (Proof of Stake) stake cryptocurrency as collateral. Both earn rewards for securing the network. Creates new blocks Earns rewards Requires specialized hardware (PoW) or capital at stake (PoS) Archive Node Everything a full node stores, plus historical state at every block height. Complete history ~15+ TB for Ethereum Used by explorers, analytics platforms, and enterprise tooling Why Peer-to-Peer Instead of Client-Server A traditional web service is client-server: your browser requests data from a company's servers. If those servers go down, the service is unavailable. That's a single point of failure by design. Blockchain networks use peer-to-peer (P2P) architecture instead. Every participant is simultaneously a client and a serv

Lessons from building a small VPN service around standard WireGuard clients instead of a proprietary app When you look at a commercial VPN product, the app seems to be the product: a polished interface, a country list, and a large Connect button. I chose the opposite approach. Instead of building another VPN client, I decided to give users a standard WireGuard configuration that they could import into an existing client. That decision removed a lot of client-side work — but it also exposed where the real complexity of a VPN service actually lives. Why build another app if WireGuard already has one? The usual commercial VPN flow is straightforward: install the vendor's app, sign in, choose a location, and connect. A proprietary client can manage server selection, subscriptions, kill switches, automatic reconnects, diagnostics, updates, and support in one place. But for a small service with one or a few locations, I had to ask a more basic question: do I really need to build and maintain a separate Windows, macOS, Android, and iOS client just to establish a WireGuard tunnel? WireGuard already has mature clients across the major desktop and mobile platforms. A user can import a configuration file or scan a QR code and get a normal VPN toggle. On paper, that looked like a very attractive tradeoff: less client code, fewer update mechanisms, fewer installers, and a smaller attack surface to maintain. What I underestimated was that the app was never going to be the hardest part. A .conf file is not just a settings file The first architectural lesson was simple but important: a WireGuard configuration is effectively a credential. It contains the client's private key. A QR code that represents the same configuration contains the same sensitive material in another form. That immediately creates product problems that have nothing to do with the tunnel itself. How do you show the configuration safely? What happens if the user loses it? Can you issue a replacement without leavin

I used to think IPv4 addresses were just random numbers until recently. It blew my mind when I started digging and understanding that they have an anatomy where every number after the dot means something very important. Note: To understand what IP addresses are, please consult this post because I won't be going over them here. IP Addresses: Digital Connectivity What is IPv4 in the First Place? IPv4 is short for Internet Protocol version 4 . As you might have already realized, it's the 4th version of the early test designs during the development of the Internet Protocol in test labs in the 1970s. The first real release, v4, came out in 1981 in a public document called RFC 791. RFC 791: STD 5: Internet Protocol IPv4 is an Internet Protocol that's written in what's called Dotted Decimal Notation (e.g., 172.17.0.3 ), where each portion is separated by a dot, and these portions are called octets. For example, 172 is the first octet and 17 is the second octet (more on this later). Before We Explore What Octets Are, Let's Take a Stroll to the Basics of Binary (Simplified) Have you ever wondered why your computer or phone requires electricity to function? Though electricity can be used as a raw power source for things like fans or speakers, where it's converted into other forms of energy such as movement or sound, it's good to know that electricity can function differently in your computer's RAM or SSD. Inside your computer are billions of extremely tiny transistors. These transistors form circuits that can create and maintain different electrical states, which the computer interprets as 0s and 1s. In simple terms, 0 represents the absence of the electrical state (OFF), while 1 represents its presence (ON). These states, which we represent with 0s and 1s, are called binary digits (or simply bits). 1 bit has the possibility of representing either 0 or 1, which doesn't represent much information, and that's where multi-bits come in. Every additional bit doubles the number of

A reverse proxy sits between clients and one or more upstream services. Instead of clients communicating directly with your application, every request first passes through the proxy before being forwarded to an upstream. Mature reverse proxies such as Nginx, Envoy, and HAProxy do much more than simply forward requests. They perform tasks such as load balancing, health checks, rate limiting, metrics collection, and much more. I wanted to better understand how some of these concepts work in practice, so I built a reverse proxy in Go. Along the way I implemented request forwarding, multiple load-balancing strategies, health checks, circuit breakers, rate limiting, request logging, metrics, and graceful shutdown. If you'd like to explore Proxify as we go, you can find the project here: https://github.com/Rahmannugar/proxify Table of Contents Request Lifecycle Project Structure Configuration Reverse Proxy Load Balancing Health Checks Circuit Breakers Middleware Graceful Shutdown Running Proxify with Docker 1. Request Lifecycle At a high level, every request follows the same path through the reverse proxy. A client sends an HTTP request to Proxify instead of communicating directly with an upstream service. Proxify receives the request, selects a healthy upstream using the configured load-balancing strategy, forwards the request, waits for the upstream's response, and finally returns that response to the client. Client │ ▼ +---------------+ | Proxify | +---------------+ │ Select Healthy Upstream │ ┌───────┴────────┐ ▼ ▼ Upstream A Upstream B │ ▼ HTTP Response │ ▼ Client Although the overall flow is straightforward, every step introduces additional considerations. Which upstream should receive the next request? What happens when an upstream becomes unhealthy? How can requests be distributed efficiently across multiple upstreams? How do we prevent a failing upstream from continuing to receive traffic? The remainder of this article answers those questions by gradually buildin

I needed a VPS to run CyberPanel. Simple enough: 1 vCPU, 1 GB RAM, 10 GB SSD, IPv6 only. CyberPanel...

Por que usar o Cloudflare em vez do DNS padrão do seu registrador Escrevi esse texto depois de um perrengue aqui na empresa onde trabalho. Precisei registrar uns subdomínios, entrei no painel da Cloudflare esperando achar os registros lá e não tinha nada, fui atrás do time para entender onde aquilo estava apontando e a resposta foi que tudo passava direto pelo provedor de domínio. Quando você registra um domínio na GoDaddy, Namecheap, Registro.br ou qualquer outro provedor de domínio, ele já vem com um par de nameservers configurados por padrão. Funciona, mas "funcionar" e "ser a melhor opção para produção" são coisas diferentes, e trocar esses nameservers pelos da Cloudflare é uma das mudanças de maior custo-benefício que dá para fazer em um projeto. O que muda ao trocar os nameservers Um provedor de domínio só precisa resolver DNS: publicar seus registros A, CNAME, MX e afins, e responder consultas. A infraestrutura por trás disso varia muito de provedor para provedor e raramente é otimizada para latência global ou resiliência a ataques, porque não é o produto principal deles. A Cloudflare constrói a rede em torno de DNS, CDN e mitigação de DDoS como núcleo do negócio, e isso aparece em números concretos: a rede anycast cobre mais de 330 cidades, então uma consulta DNS ou uma requisição HTTP é respondida pelo ponto de presença fisicamente mais próximo do usuário, não por um servidor central do outro lado do mundo. Hoje a Cloudflare responde por algo em torno de 23% de todos os sites da internet. Vantagens técnicas O anycast é a base de tudo. Não existe "o servidor DNS" que pode cair: se um ponto de presença fica indisponível, o tráfego é roteado automaticamente para o mais próximo, o que reduz latência de resolução e risco de indisponibilidade. A mesma arquitetura, combinada a TTLs baixos, também acelera a propagação de mudanças: um registro DNS alterado costuma valer em minutos, enquanto em boa parte dos provedores de domínio tradicionais não é incomum esperar ho

Most VPN troubleshooting goes wrong in the same predictable way: three things get changed at once, and whatever happens next, nothing has been learned. The alternative is boring and effective — check one layer at a time, in an order that rules things out, and write down what each layer shows. One boundary before starting: troubleshooting means finding where a problem lives, not working against anyone's rules. On a network you don't control, or a device your organization manages, the policies in place stay in place. If a managed device is part of the picture, your organization's IT function is part of the troubleshooting — and switching off device security tooling is never a troubleshooting step. 1. Device basics first Start embarrassingly simple, because this layer resolves more than anyone likes to admit. Restart the VPN client. If that changes nothing, restart the device. Confirm that the operating system and the client are updated. An update that has been pending for weeks is a suspect, not background noise. Note whether anything changed around the time the problem started: an update, a new app, different settings, a different location. 2. Does the internet work without the VPN? Disconnect the VPN entirely and test ordinary browsing. If the connection is broken without the VPN, this isn't a VPN problem yet. Solve the underlying connection first, because nothing downstream is testable until this layer works. If the internet is fine without the VPN and wrong with it, you have genuinely narrowed something down. Write that down. 3. Client state: connected to what, exactly? Open the client and look, rather than assume. Is it actually connected, or still trying? Is the right profile selected — the current one, not an older entry left over from a previous setup? Disconnect and reconnect once, deliberately, and watch what the client reports. If multiple profiles have accumulated in the client, that is a finding in itself. Stale entries are a classic source of "it connect

When you open a website, send a message, or watch a YouTube video, many technologies work together in the background. As a beginner in DevOps, understanding these basic networking concepts will help you understand how applications communicate over the internet. **What Is a Protocol? A protocol is a set of rules that devices follow when communicating with each other. Think about two people having a conversation. For communication to be successful, both people must speak the same language and follow simple rules, like taking turns to talk and listening before responding. Computers work the same way. They use protocols to know how to send, receive, and understand information. Without protocols, computers would not be able to communicate with one another. **2. What Is Packet Switching? **Imagine you want to send a large book to a friend. Instead of sending the entire book in one huge package, you divide it into many smaller packages. Each package travels separately and, when they all arrive, your friend puts them back together in the correct order. This is exactly how the internet works. When you visit a website, your data is broken into small pieces called packets. Each packet travels across the internet and is reassembled when it reaches its destination. This process is called packet switching, and it makes internet communication faster and more reliable. **3. What Is an IP Address? **Every house has a unique address that helps delivery drivers know where to deliver packages. Similarly, every device connected to the internet has a unique Internet Protocol (IP) address. An IP address helps the internet know exactly where information should be sent. Without an IP address, websites, computers, and phones would not know where to send or receive data. **4. What Is TCP/IP? **Breaking data into packets is not enough. The packets must also arrive correctly. This is where TCP/IP (Transmission Control Protocol/Internet Protocol) comes in. IP finds the correct destination for ea

Hello, I'm Maneshwar. I'm building git-lrc, a Micro AI code reviewer that runs on every commit. It is...

Every five minutes or so, my entire Windows machine would drop off the network for a few seconds — not just WSL, the whole host. Browser tabs would stall, calls would drop, and it only happened while WSL2 was running. This is the story of finding that, plus the WSL memory-tuning landmines I hit right alongside it. The flapping The symptom was a host-wide network blip on a short, regular interval, correlated tightly with WSL2 being up. The cause: WSL2's default networking mode creates a virtual NAT switch on the Windows side, and on this machine that virtual switch was intermittently conflicting with the real network adapter — enough to cause the whole host to briefly renegotiate its connection. The fix was switching WSL2's networking mode entirely, via .wslconfig (on Windows, not inside the Linux filesystem): [wsl2] networkingMode = mirrored dnsTunneling = true autoProxy = true Mirrored networking makes the WSL2 interface share the host's actual network identity instead of sitting behind a separate virtual NAT switch. You can confirm it actually took effect (rather than just trusting the config file) by checking, from inside WSL after a full restart, that its network interface holds the same IP as the Windows host, that the default route points at the real LAN gateway rather than a private NAT range, and that loopback carries mirrored mode's marker address rather than a 172.x NAT address. If any of those don't match, the setting isn't actually active yet. Worth noting: this requires a reasonably recent WSL version and Windows build. If you're on an older one, mirrored mode may not be available at all. The memory landmines, found the hard way Separately — and this had actually caused full VM crashes, not just hangs, at one point — I'd been carrying a few .wslconfig settings that looked reasonable and were each, individually, a documented source of instability: An explicit kernelCommandLine override. Resizing swap past a few GB, which forces WSL to rebuild its virtual

Hello, I'm Maneshwar. I'm building git-lrc, a Micro AI code reviewer that runs on every commit. It is...

Ethereal Bytecode for the Network: Unlocking XDP's Magic! Hey there, fellow tech enthusiasts! Ever felt like the traditional networking stack in your Linux kernel was a bit… sluggish? Like it was taking the scenic route when you needed it to be a supersonic jet? Well, let me introduce you to a superhero that swoops in and turbocharges your network packet processing: eBPF, specifically in the context of XDP (eXpress Data Path). Forget the days of wrestling with complex kernel modules or praying for better hardware offload. eBPF and XDP offer a revolutionary, in-kernel, safe, and incredibly efficient way to program packet processing at the very edge of your network interface. Think of it as giving your network card a tiny, super-smart brain, capable of making lightning-fast decisions before the packet even bothers the main kernel stack. Pretty cool, right? So, buckle up as we dive deep into the wonderful world of XDP and eBPF, demystifying its power and showing you why it's becoming the darling of modern networking. 1. The "What's the Big Deal?" Section: Introduction to XDP & eBPF Imagine a bustling highway (your network). Traditional networking is like having every car stop at a toll booth, get inspected, and then directed by a central traffic controller. This works, but it can get congested. XDP, on the other hand, is like having intelligent on-ramps where some cars can be instantly identified, rerouted, or even rejected before they even hit the main highway. eBPF (extended Berkeley Packet Filter) is the technology that makes this possible. It's a powerful, sandboxed virtual machine that runs within the Linux kernel. Unlike traditional kernel modules, which can potentially crash your entire system if written incorrectly, eBPF programs are rigorously verified by the kernel for safety and correctness before they are allowed to execute. This means you get the power of kernel-level access without the existential dread of a kernel panic. XDP (eXpress Data Path) leverages

What We Learned Building a Location-Aware Contact Management App Most contact apps are built like digital phonebooks. They store a name, phone number, email, maybe a company name, and then leave the user to remember everything else. That works when someone has 50 people saved. It starts breaking when someone has hundreds or thousands of professional connections from events, client meetings, referrals, business cards, conferences, online communities, and local networking groups. The hard part is not storing people. The hard part is helping users find the right person at the right time. While building a location-aware contact management app, we learned that contact data becomes far more useful when it is connected to context: where someone is, how the user met them, what they discussed, what industry they belong to, and why the relationship matters. Here are some product, UX, and privacy lessons we learned along the way. 1. A contact list is not the same as a usable network A normal contact list answers one basic question: “Do I have this person’s number?” But professionals usually need better questions answered: Who do I know in this city? Who did I meet at that event? Which industry contacts are nearby? Who should I follow up with before visiting this area? Who was that consultant I met last month? Which contacts are important but easy to forget? This is where the product problem becomes interesting. A user may technically have the contact, but still fail to use the relationship because the contact is buried inside a long list. So the first learning was simple: Saving contact details is not enough. The app needs to help users retrieve useful relationships when the context matters. That changed how we thought about the product. We were not just designing a place to store people. We were designing a system to make saved professional relationships easier to act on. 2. Location context changes the experience Most contact managers are list-first. You search by name, comp

I'm the developer of DeviceShelf, a local-first network scanner for desktop, mobile and a headless server edition. Until this week the iOS app only existed on TestFlight. Apple has now approved version 1.3.0, so for the first time you can get it straight from the App Store: DeviceShelf on the App Store . What the app does on a phone The iOS app is not a companion viewer. It runs the same scanning engine as the desktop version: it scans the network you're on, identifies devices (vendor, type, OS fingerprint), shows open ports per device, builds a security report, and raises presence alerts when devices appear or drop off. You can export and share results from the phone. The multicast entitlement iOS restricts multicast traffic for ordinary apps, and SSDP/UPnP discovery depends on it. Apple grants the multicast entitlement on request, and DeviceShelf's App Store build has it. In practice, UPnP/SSDP devices show up in scans on the phone the same way they do on desktop. Licensing The download is free and comes with a trial. Full features unlock in one of two ways: activate a DeviceShelf license, which covers desktop, mobile and the server edition with a single purchase, or use the in-app purchase upgrade on iOS. Pricing is on the website if you want the details. Local-first, on mobile too Scans stay on the device. There is no cloud account, and the AI-assisted device identification is bring-your-own-key; no key is bundled or required. The app is still young, and a phone is an unforgiving place for a network scanner. If it mislabels a device on your network or misses one entirely, I'd genuinely like to hear about it. Website: deviceshelf.app

local + echo = locho Sometimes you don't need access to a machine. You don't need a shell. You...

Introduction Linux is the backbone of modern infrastructure. From cloud servers and firewalls to SIEM platforms and security tools, Linux runs silently behind most enterprise environments. For a Security Operations Center (SOC) analyst, understanding Linux is not optional — it is a core skill. One of the most critical security mechanisms in Linux is its file permission and ownership model. Attackers abuse permissions to execute malware, hide persistence, escalate privileges, and erase evidence. SOC analysts rely on permission analysis to detect anomalies, investigate incidents, and build accurate timelines. Become a Medium member This article covers Linux File Permissions and Ownership in deep detail from a SOC analyst’s perspective. It is designed to take you from absolute beginner to security-aware professional, with real-world examples, attack scenarios, and investigation insights. Why Linux File Permissions Matter in SOC In SOC operations, analysts constantly deal with: Authentication logs System logs Application logs Scripts and binaries Configuration files Evidence files during incident response Every one of these objects is protected by Linux permissions. From a SOC perspective: Incorrect permissions = security risk Permission changes = potential indicator of compromise Executable permissions = possible malware Ownership changes = possible log tampering Understanding permissions allows SOC analysts to: Detect unauthorized access Identify privilege escalation Spot malware execution Preserve forensic evidence Reconstruct attacker activity Understanding Linux File Permission Basics Linux follows a Discretionary Access Control (DAC) model. This means: The owner of a file controls who can access it Permissions define what actions are allowed Every file and directory in Linux has: A type Permissions An owner (user) A group These attributes decide: Who can read the file Who can modify it Who can execute it Viewing Permissions Using ls -l The most common command to i

Week 0 of my DevOps Micro Internship was about the foundations—the parts of the internet you use every day without thinking about them. The exercise that made it click was a simple scenario: a friend launches an online bookstore called EpicReads, hosted on a server in Finland, and asks how people anywhere in the world can open it. The answer is a short chain of technologies working together. The Chain of Technologies Packet Switching: When someone opens the site, their request does not travel as one big lump. Packet switching breaks the data into small packets that each take the best available path across the network and get reassembled at the other end. This is what keeps the internet fast and resilient even across continents. IP Addresses & TCP/IP: Every device on the way has a unique IP address, like a postal address, so the user's computer and the Finland server can actually find each other. The TCP/IP suite runs the conversation: IP handles addressing and routing, while TCP makes sure the packets arrive complete and in the right order, asking again for anything that went missing. HTTP & HTTPS: On top of that sits HTTP and HTTPS, which define how the browser and server actually exchange the web pages. HTTPS adds encryption, so a customer's details and payment stay private. DNS: The last piece is DNS. Nobody wants to type an IP address, so DNS acts as the internet's phonebook, translating epicreads.com into the server's IP. To point a domain at an IPv4 address, you use an A record . The Biggest Takeaway The biggest lesson for me was not any single term. It was seeing how these layers hand off to each other so cleanly that the whole thing feels instant to a user. Understanding that chain is the groundwork for everything else in DevOps, because once you know how a request really travels, troubleshooting stops being guesswork. P.S. This post is part of the DevOps Micro Internship with Agentic AI Cohort 3 by Pravin Mishra. You can begin your DevOps journey by joining

Today I'm excited to launch RegionCheck , a tool for testing, monitoring, and debugging endpoints from cloud regions around the world. The idea is simple - test an endpoint's DNS and HTTP connectivity and response from a defined set of cloud regions. Whether you're troubleshooting an API, validating a deployment, checking DNS propagation, or investigating latency, seeing the results from multiple cloud regions can quickly reveal issues that aren't obvious from your own machine. What is RegionCheck? RegionCheck lets you run endpoint checks from AWS, Azure, and Google Cloud regions without provisioning infrastructure or maintaining test instances. Current capabilities include: HTTP endpoint testing DNS lookups TLS certificate validation Continuous monitoring with alerts Side-by-side comparison across cloud providers and regions Shareable result pages for collaboration API/MCP access for automation and agents Why I built it When debugging production issues, I often wanted to answer questions like: Is DNS returning the same result everywhere? Or is geo-DNS returning the results intended? Is TLS certificate propagation for my CDN working as intended? Is one region significantly slower than another? Is my CDN caching working as expected? Are my geo-HTTP redirects working as intended? (For some interesting examples try www.yahoo.com and www.cnn.com in non-US regions) There are many tools that exist that provide these answers, but nothing that answers all of these questions in one place. That's what RegionCheck aims to provide. Who it's for RegionCheck is designed for engineers who work with cloud infrastructure, including: DevOps engineers Site Reliability Engineers (SREs) Platform engineers Backend developers Anyone who likes to take a peek at backend infrastructure Try it out RegionCheck is available at https://regioncheck.io You can run free checks directly from the website; or create an account to access monitoring, alerting, the API, and additional features. I'd love

I have been working on building a private, secure network accessible from anywhere. The goal was to connect my mobile phone and my local development laptop using a WireGuard VPN , hosting the central gateway on a free-tier Google Cloud Platform (GCP) e2-micro instance. I wanted to access my self-hosted services, specifically my Docker-hosted Open WebUI , running on my local home Wi-Fi connected laptop, directly from my phone using mobile data. It sounded straightforward. But if you read my other from scratch journeys, you might have already guessed, it was not. The Setup My architectural plan was a simple hub-and-spoke topology: The Hub: GCP VM ( 10.66.66.1 ) with IPv4 forwarding enabled. Spoke 1 (My Phone): 10.66.66.2 Spoke 2 (My Laptop): 10.66.66.3 I wrote my server configurations, enabled IP forwarding ( net.ipv4.ip_forward=1 ), wrote the iptables rules to allow forwarding between peers, and started the interfaces. Then came the moment of truth. I tried to bring up the tunnel. Absolute silence. No packet moving from anywhere. Hurdle 1: The Classic Cloud NAT Trap (Internal vs. Public IP) Before I could even worry about routing packets between my phone and laptop, I couldn't even get them to handshake with the GCP server. Like many of us do when working inside a VM, I had run ip addr on the GCP instance to grab its IP address for my client configurations. I set up the WireGuard peers to point to this IP. Nothing connected. The Culprit: GCP (and AWS) operates on a 1:1 NAT mapping. The virtual network interface inside your VM only sees and binds to a private, internal cloud IP (e.g., 10.128.0.x ). The public IP assigned to your instance lives outside the VM at the VPC gateway level. By putting the internal IP into my client configs, my phone and laptop were trying to connect to a private address that didn't exist on their local networks. The Fix: I had to swap the internal IP in the client configurations with the GCP Ephemeral/Static External IP . Once the handshake