Server down because of portflood attack by the server

Hi Guys,

Kindly help me on these,

I received below messages from the server people,

"your Server/Customer with the IP: x.x.x.x (x.x.x.x) has attacked one of our servers/partners. The attackers used the method/service: portflood on: Thu, 04 Aug 2016 13:59:17 +0200. The time listed is from the server-time of the Blocklist-user who submitted the report. The attack was reported to the Blocklist.de-System on: Thu, 04 Aug 2016 13:59:37 +0200

The IP has been automatically blocked for a period of time. For an IP to be blocked, it needs to have made several failed logins (ssh, imap…), tried to log in for an “invalid user”, or have triggered several 5xx-Error-Codes (eg. Blacklist on email…), all during a short period of time. The Server-Owner configures the number of failed attempts, and the time period they have to occur in, in order to trigger a ban and report. Blocklist has no control over these settings.

Please check the machine behind the IP x.x.x.x (x.x.x.x) and fix the problem. To search for AS-Number/IPs that you control, to see if any others have been infected/blocked, please go to: https://www.blocklist.de/en/search.html?as=62567"

Thanks!