🔄 Topic

Testing connectivity between systems and verifying whether services are reachable over the network.

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🎯 Goal

Understand how to verify whether a remote service is accessible and correctly listening on a port.

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🛠 What I Did

Used tools like:

• Test-NetConnection (Windows)
• netcat (nc)
• ss -tulpn (Linux)

to check:

• whether port 22 was reachable
• whether services were listening

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🔗 Key Cybersecurity Connections

Port connectivity testing is essential for:

• troubleshooting infrastructure
• validating service availability
• detecting exposed services

Attackers use the same techniques during:

• reconnaissance
• network scanning
• lateral movement

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🔍 Investigation Questions

• Is the target port open?
• Is a service actually listening?
• Is the issue network-level or host-level?

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🚨 Detection Opportunities

• port scanning activity (multiple connection attempts)
• unusual probing across multiple hosts
• repeated connection failures

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🧭 MITRE ATT&CK Techniques

• T1046 — Network Service Discovery

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⚠ Challenges

Distinguishing between:

• network reachability
• service availability

A host can be reachable but still not accept connections.

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📚 What I Learned

• open port ≠ reachable service
• tools must be used together for validation
• connectivity issues must be broken down step by step

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➡ Next Steps

• simulate port scanning scenarios
• analyze logs generated by connection attempts

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🧠 Reflection

This reinforced a key principle:

Always test assumptions at the network level.

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🧩 Lessons Learned

What worked

Using multiple tools to verify connectivity.

What broke

Assuming reachability meant service availability.

Why it broke

Incomplete understanding of networking layers.

Fix / takeaway

Validate each layer independently.

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📈 Skill Progression Context

This builds core networking and investigation skills used daily in SOC environments.

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😄 TL;DR

Just because you can ping it…
doesn’t mean you can talk to it.