Getting Started with Netalyzr CLI — Installation & First ScanNetalyzr is a network diagnostic tool that helps you understand how your local network and Internet connection behave. The Netalyzr CLI brings this functionality to the command line, making it easy to script, automate, and run diagnostics on servers, routers, or remote machines.
What Netalyzr CLI does
Netalyzr CLI runs a suite of tests that examine:
- DNS resolution behavior
- TCP and UDP connectivity, including port reachability and path MTU
- HTTP(S) proxying and content modification
- NAT, firewall, and middlebox interference
- Timeouts, retransmissions, and other transport-layer anomalies
Netalyzr CLI provides a consolidated report of these tests, helping you pinpoint misconfigurations, ISP interference, or broken devices on a network.
Who should use it
- Network administrators troubleshooting connectivity or middlebox behavior
- DevOps engineers automating network health checks
- Researchers studying real-world network measurement and middlebox effects
- Security analysts verifying path and endpoint behavior
System requirements
Netalyzr CLI runs on common Unix-like systems. Minimum requirements:
- A system with a POSIX-compatible shell (bash, zsh, sh)
- Python 3.8+ (if the CLI is Python-based) or the language/runtime specified by the project
- Internet connectivity for remote tests
- Administrative (root) privileges for some tests (e.g., raw sockets, packet capture, setting MTU)
Check the specific package documentation for exact runtime/version requirements.
Installation
Below are general installation approaches. Replace package names and commands with those from the official project repository or package manager you trust.
- Install from a package repository (preferred if available)
- Debian/Ubuntu:
sudo apt update sudo apt install netalyzr-cli - Fedora:
sudo dnf install netalyzr-cli
-
Install via pip (if distributed as a Python package)
python3 -m pip install --upgrade pip python3 -m pip install netalyzr-cli -
Install from source
- Clone the repository:
git clone https://example.org/netalyzr-cli.git cd netalyzr-cli - Install dependencies and the tool:
python3 -m pip install -r requirements.txt sudo python3 setup.py install
- Use a container (quick isolation)
docker run --rm -it --net=host ghcr.io/example/netalyzr-cli:latest /bin/bashAdjust commands to the actual repository, package name, or container image used by Netalyzr CLI.
Configuration & permissions
- Many tests require elevated privileges. Run scans with sudo when needed:
sudo netalyzr-cli scan --target default - Configure proxy settings or API keys (if the tool uploads results) in a config file, e.g., ~/.netalyzr/config.json:
{ "upload": true, "server": "https://netalyzr.example.org/api", "api_key": "YOUR_API_KEY" } - Set a profile or runtime flags to control which tests run and their time budget.
Running your first scan
A minimal first-run command (may differ by implementation):
netalyzr-cli scan Common useful flags:
- –output
— write results to file (json, html) - –quiet — reduce console noise
- –profile
— use a saved profile of tests - –no-upload — keep results local
Example:
sudo netalyzr-cli scan --output results.json --no-upload This runs the default test suite, stores a JSON report locally, and avoids sending data to a central server.
Understanding the core sections of the report
A typical Netalyzr CLI report includes:
-
Summary
- High-level verdicts: success, warnings, failures
- Key findings (DNS misconfiguration, blocked ports, MTU problems)
-
Connectivity tests
- Public IP discovery
- IPv4/IPv6 reachability
- NAT type and local vs public port mappings
-
DNS tests
- Resolver behavior, DNSSEC validation, CNAME handling
- Response tampering detection
-
Transport-layer tests
- TCP handshake anomalies, retransmission rates, blocked ports
- Path MTU discovery results and fragmentation behavior
-
HTTP/HTTPS and middlebox detection
- Proxy detection, TLS interception checks, content alteration
-
Latency and bandwidth indicators
- Round-trip times, jitter, basic throughput estimates
-
Recommendations
- Actionable guidance for each issue detected (e.g., adjust MTU, fix DNS settings, contact ISP)
Example: Interpreting a common issue
Issue: “TCP SYNs to port 443 succeed but payloads are dropped”
What it means:
- The TCP handshake appears to complete, but application-layer data is not transmitted reliably. This can indicate a misbehaving middlebox or broken NAT state.
Suggested actions:
- Re-run tests while capturing packets (tcpdump/tshark) to confirm the location of drops.
- Test from another network to isolate ISP vs local device.
- Temporarily disable firewall/NAT device to check behavior.
Automating regular checks
Create a cron job to run daily and save results:
0 3 * * * /usr/bin/netalyzr-cli scan --output /var/log/netalyzr/$(date +%F).json --no-upload Parse JSON results and alert on regressions (e.g., new failures or increased latency).
Tips & best practices
- Run scans from both inside and outside NAT to compare behavior.
- Use –no-upload for privacy when you don’t want reports sent.
- Combine Netalyzr CLI with packet captures when investigating complex issues.
- Keep the tool updated; tests and heuristics improve over time.
Troubleshooting installation problems
- Missing dependencies: install required language runtimes and libraries listed in requirements.
- Permission errors: run with sudo or adjust capabilities (e.g., setcap) to allow raw socket use.
- Network restrictions blocking test endpoints: use –no-upload and run local-only subsets.
Further reading and resources
- Official Netalyzr CLI documentation (check the project repo)
- Network measurement and middlebox detection literature
- Tools to pair with Netalyzr: tcpdump/tshark, mtr, dig, iperf3
If you want, I can: provide a concrete install command for your OS, write a sample cron script that parses results for alerts, or walk through interpreting a real scan output — send me the platform or a sample report.
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