Add new Alerter: IDMEF with Prelude SIEM

[ToToL]

Hello

Here is a contribution to make Elastalert natively compatible with Prelude SIEM.

IDMEF (RFC 4765) is intended to be a standard data format that automated
intrusion detection systems can use to report alerts about events
that they deem suspicious.

Prelude SIEM is an OpenSource SIEM: https://www.prelude-siem.org and is in major Linux Distributions (RedHat/CentOS/Fedora/Debian/Ubuntu/etc.)

As other IDS already natively compatible with Prelude SIEM (Suricata, OSSEC, Wazuh, ClamAV, etc.) I think this is a good idea to have Elastalert compatible with Prelude SIEM.

Regards

[ToToL]

Hello

"prelude" comes with python3-prelude package on linux distribution. Maybe setup.py is not the right place for this ?

Regards

[ToToL]

Hello

Prelude is now on Pypi : https://pypi.org/project/prelude/

[ToToL]

Hello

■README.md
Need to add "IDMEFAlerter" under Zabbix
Done

■ docs/source/ruletypes.rst
Need to add explanation about IDMEFAlerter settings
Done

Regards

[ToToL]

Hello

I tried bu the Dockerfile-test does not seems to be taken in account.

Regards

[ToToL]

Travis use an old Ubuntu. For libprelude with python3 support, we need at least Ubuntu Focal :(

[ToToL]

Done for conflict

[ToToL]

Hello

Travis use Ubuntu Xeinal for building but python3.6-prelude comes with ubuntu bionic (next LTS). So it is not possible to install dependencies through this.

To install it with pip, as described in https://pypi.org/project/prelude/ you need to :
yum group install "Development Tools"
yum install python-devel

Is it possible to add this to the configuration ?

Regards