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SNMP v1, v2c and v3 Credentials

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In this lesson, you will learn:

  • What SNMP credentials are
  • v1, v2c and v3 compared
  • SNWR’s SNMPv3 credential

🔁 Quick look back: Last time: Linux and Unix: SSH, sudo and Least Privilege. You learned how the snowdisc SSH key and sudo list give just enough access.

1 The Problem: SNMP Community Strings Are Easy to Guess

Older SNMP uses a ‘community string’ as its password. Often it’s still ‘public’. That means:

  • Anyone who guesses it can read device details.
  • It travels in plain text.

🎯 The problem: SNMP community strings are easy to guess and read.

👉 The fix: Use SNMPv3, with a user name, password and encryption.

Table comparing SNMP versions.
Figure 1. SNMP versions compared.

2 SNMP credentials

Key term: Community string

A shared word used as a password in SNMP v1 and v2c.

Key term: SNMPv3 user

A named user with authentication and encryption settings.

The credential must match what the device expects: user name, and the authentication and privacy settings.

3 Getting it right

  • Ask the network team for the exact SNMPv3 settings.
  • Use read-only access.
  • Test on one device before scanning all.

4 Project Clear View: How We Implemented It

📍 Situation: Ravi set up a read-only SNMPv3 user on SNWR’s devices.

🧭 Decision: Create the matching credential and test it on one switch.

🛠️ Steps we took:

  1. Got the user name and settings from Ravi.
  2. Created SNWR SNMPv3 Read-Only on snwrtest.
  3. Tested against snwr-core-sw-01.
  4. Tested against snwr-vpn-gw-01 in the DMZ.

✅ What we verified:

  • Both devices answered.
  • No community strings are used anywhere.

📁 Evidence: SNWR SNMPv3 Read-Only in the credential register.

5 Quick recap

  • SNMP v1 and v2c use community strings, sent in plain text.
  • SNMPv3 has users, passwords and encryption.
  • Match the device’s exact v3 settings.
  • Use read-only access.

6 Check yourself

Think of your answer first. Then tap to check.

1 Why avoid SNMP v2c? Show answer

Its community string is easy to guess and travels in plain text.

2 What does an SNMPv3 credential include? Show answer

A user name and authentication and privacy settings.

3 Which two devices did SNWR test first? Show answer

snwr-core-sw-01 and snwr-vpn-gw-01.

Nice work! SNWR’s network credential is secure. 🎉
Next up: Application, Database, VMware and Platform Credentials

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