IDS/IPS for RHEL 3.0/4.0

[Opesh Alkara]

I was planning to implement *Network based* IDS/IPS on REHL 3.0 (or 4.0 whichever is stable and secure).....

I have a set of servers that are open to web and are running revenue generating sites. These servers are vulnerable and require 24/7 attention. Others are not open to web, but to clients and still they need to be secured.

It would be grateful if any can share the experience of implementing and suggest me which IDS/IPS application suits best to my scenario:

Security level :  High
Network Size:  60-70 servers (increasing)
OS Type (of servers) : RHEL 3.0 and few RH 7.
Bandwidh Usage (by IDS/IPS machine):  As least as possible (business critical).
Resource (CPU, MEM, DISK) usage by IDS/IPS sys: Optimum. (dedicated machine).
Licence type (for IDS)    : GNU preffered.

Thanks,
Opesh Alkara