Best security Option's

Hi all
i have now got my freepbx/asterisk working perfect on my cheap £6 Centos 6 vps

However i now need to setup security

Whats the best options i am already getting hack attempts in my logs!

How to i enable iptabes and install fail2ban is this the best option?

[2013-09-25 20:21:19] VERBOSE[15281][C-0000008a] pbx.c: – Executing [[email protected]:6] Log(“SIP/50.97.253.182-00000094”, "WARNING,“Rejecting unknown SIP connection from 192.187.115.90"”) in new stack
[2013-09-25 20:21:19] VERBOSE[15281][C-0000008a] pbx.c: – Executing [[email protected]:6] Log(“SIP/50.97.253.182-00000094”, "WARNING,“Rejecting unknown SIP connection from 192.187.115.90"”) in new stack
[2013-09-25 20:21:19] WARNING[15281][C-0000008a] Ext. s: “Rejecting unknown SIP connection from 192.187.115.90”
[2013-09-25 20:21:19] WARNING[15281][C-0000008a] Ext. s: “Rejecting unknown SIP connection from 192.187.115.90”

Is this hack Attempts!

Yes

whois 192.187.115.90
[Querying whois.arin.net]
[whois.arin.net]

ARIN WHOIS data and services are subject to the Terms of Use

available at: https://www.arin.net/whois_tou.html

Query terms are ambiguous. The query is assumed to be:

“n 192.187.115.90”

Use “?” to get help.

The following results may also be obtained via:

http://whois.arin.net/rest/nets;q=192.187.115.90?showDetails=true&showARIN=false&ext=netref2

DataShack, LC DSV4-7 (NET-192-187-96-0-1) 192.187.96.0 - 192.187.127.255
Mahmoud Aldadah DS-115-90-94 (NET-192-187-115-88-1) 192.187.115.88 - 192.187.115.95

ARIN WHOIS data and services are subject to the Terms of Use

available at: https://www.arin.net/whois_tou.html

If you are using asterisk 11 then

http://sourceforge.net/p/raspbx/discussion/tutorials/thread/6288a838/

should work for you.