---
name: Carl Vargklint
summary: Operations and Linux specialist in email, networking and security
profile: >
    Carl is a systems administrator and operations engineer with ten years in
    Linux environments. He currently runs the email platform at a defence
    group, from mail flow and delivery to authentication and security, and is
    migrating encrypted communications and network services to more modern
    solutions. Before that he introduced ISO 27001-aligned security practices,
    server hardening and TOTP for clients, building on several years of NOC
    operations. In his spare time he works with radio and RF: SDR-based signal
    geolocation, security analysis of LoRa mesh protocols, and hardware for
    security conferences.
lang: en
classification: open
colorlinks: true
header-includes:
  - \usepackage{needspace}
external: false

contact_info:
  - Phone +46 790-75 50 42
  - c.vargklint@gmail.com
  - linkedin.com/in/carl-vargklint
  - github.com/Superminaren

assignments:
  - span: 2023 - present
    location: SAAB AB
    category: defence industry
    role: Linux Systems Administrator
    description: >
        Runs Linux environments in group IT, working remotely. Manages the
        email platform from mail flow and delivery to authentication and
        security, and is migrating encrypted communications and network
        services to more modern solutions.
    keywords: Linux, email operations, SPF/DKIM/DMARC, encrypted communications, networking

  - span: 2022 - 2023
    length_months: 16
    location: Exicom Software AB
    category: software development
    role: Linux Specialist and Operations Engineer
    description: >
        Full-time assignment responsible for Linux operations. Drove the
        adoption of ISO 27001-aligned security standards in the workplace and
        rolled out password management, server hardening and TOTP.
    keywords: Linux, ISO 27001, server hardening, TOTP, password management

  - span: 2021
    length_months: 3
    location: Blockworks AB
    category: IT consulting
    role: Senior IT Consultant
    description: >
        Set up new private cloud environments and maintained hardware and
        software both on-site and in the cloud.
    keywords: Private cloud, virtualisation, on-site operations

  - span: 2021
    length_months: 5
    location: Opsdis AB
    category: IT consulting
    role: DevOps Consultant
    description: >
        Worked in Linux environments with observability and development.
    keywords: Linux, observability, DevOps, automation

  - span: 2019 - 2021
    length_months: 28
    location: Iver AB / DGC AB
    category: IT operations
    role: NOC Specialist
    description: >
        Linux operations, monitoring, backup and maintenance in a Network
        Operations Center.
    keywords: Linux, NOC, monitoring, backup

  - span: 2017 - 2018
    length_months: 18
    location: Thalamus IT
    category: IT consulting
    roles:
      - role: IT Technician, Stockholm County Council
        length_months: 6
        description: >
            IT support and technician work in a Windows environment. Moved on
            to an on-site assignment at Karolinska University Hospital.
      - role: On-site Technician, New Karolinska Solna (Nya Karolinska Sjukhuset)
        length_months: 7
        description: >
            On-site technician for Windows Server, clients and networking.
            Helped build up the hospital's IT infrastructure.
    keywords: Windows Server, client management, networking, public sector
---

# Skills

* Linux: systems administration, hardening and operations — 10 years
* Email operations: mail flow, delivery, authentication and filtering
* Networking and tunnels, including AX.25 and AMPRNet — 5 years
* Observability and monitoring — 5 years
* Virtualisation — 5 years
* Containerisation — 3 years
* Web and reverse proxy: Apache, Nginx, Caddy — 6 years
* Automation with Ansible — 3 years
* Database management — 3–4 years
* IBM AIX — 2 years
* Programming — 10+ years
* Local AI: inference on own hardware, agentic systems and model training
* Embedded systems and PCB design: ESP32, RP2040, CH32V003, ATtiny

# Experience

## Infrastructure and operations
* Email operations in a group-wide environment: mail flow, delivery,
  authentication and security
* Migration of encrypted communications and network services
* Server hardening, password management and rollout of two-factor
  authentication (TOTP)
* Private cloud environments, from setup to ongoing management
* Monitoring, backup and incident management in a NOC

## Security
* Introduction of ISO 27001-aligned security standards
* Security reviews of infrastructure and workplace solutions
* Crisis and emergency communications

## AI
* Running large language models locally, including with llama.cpp
* Choosing models and quantisation to fit memory and compute budgets
* Hardware selection and benchmarking for inference on own equipment
* Agentic systems: models that use tools and carry out multi-step tasks
* Training and fine-tuning of custom models

## Radio and RF
* SDR and RF security work with the Ettus B210 and KrakenSDR
* Signal geolocation and monitoring of drone signals
* Satellite communications via QO-100
* Security analysis of mesh protocols (Meshtastic and MeshCore): routing,
  cryptography, known CVEs, jamming resilience and governance model

# Assignments and Employment

[//0]: <> (Populated automatically from "assignments" in the header)

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% columns are minipages where \Needspace does not behave meaningfully.
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```

# Personal Projects and Open Source

* **Meshtastic/MeshCore security comparison** — independent analysis of two
  LoRa mesh protocols: routing behaviour, cryptography including known CVEs,
  jamming resilience and governance model.
* **Conference tooling for SEC-T** — Python tools for the conference: a
  Meshtastic notifier that announces pretalx sessions before and after they
  start, and a uConsole-based receiver for the public LoRa channel.
* **Badge development** — hardware and software for conference badges on
  ESP32, RP2040, CH32V003 and ATtiny, including LED matrices and audio
  playback.
* **Delay-Exporter** — Prometheus exporter for delay data from Stockholm
  public transport (SL) bus services.
* **Amateur radio (SA0CVK)** — active in SDR and RF. Among other things,
  designed a battery and audio board for the QRP Labs QMX+ and shared it with
  the amateur radio community.

# Education and Certifications

2021
: Driving licence, category B

2015
: Electronics design, networking and computer science, Fredrika Bremer upper
  secondary school

2014
: Amateur radio licence, call sign SA0CVK

# Community Roles

* Board member, SK0QO
* Member, AMPRNet Stockholm — 2024–2025
* Operator, Tekniska museet (Swedish National Museum of Science and Technology)
* Teaches soldering workshops at the SEC-T and Security Fest security
  conferences
* Builds hardware and simpler designs for both conferences
* Designed the Security Fest 2025 badge in two days, after the original
  designer dropped out with the deadline already passed

# Languages

* Swedish: native
* English: fluent