WARNING: It is important to realize that if someone has read-write access to any of your SNMP devices, he can gain control of those devices by using SNMP (for example, he can set router interfaces, switch ports down, or even modify your routing tables). One way to protect your community strings is to use a Virtual Private Network (VPN) to make sure your network traffic is encrypted. Another way is to change your community strings often. Changing community strings isn't difficult for a small network, but for a network that spans city blocks or more and has dozens (or hundreds or thousands) of managed hosts, changing community strings can be a problem. An easy solution is to write a simple Perl script that uses SNMP to change the community strings on your devices.
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