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IP Whitelisting in SAP Cloud Platform Integration

Introduction

This blog proposes a stop-gap solution for all the customers, who wish to do the IP Whitelisting for all the incoming requests into SAP Cloud Platform Integration.

This is a short-term solution from SAP Cloud Platform Integration and I recommend all the customers to switch to Platform level IP Whitelisting as soon as it is available for consumption.

In this blog, I would explain the necessary steps needed to handle IP Whitelisting for an integration flow that accepts incoming requests through HTTP Sender adapter.  The scenario mentioned here is an example for blocking an incoming request from a suspected IP address. You can apply the same approach for any other integration flows having SOAP,IDoc,AS2,OData sender adapters.

 NOTE:  Since it is easy to forge an x-forwarded-for header, the information provided below should be used with care.

 

Scenario: Block requests from a particular IP address using script:

  • Add the x-forwarded-for header in Allowed header(s) of the integration flow Run time configuration.

 

  • Write the  below sample script immediately after the sender adapter(applicable for HTTPS, AS2 and OData ) to block incoming requests from suspected client IP.

 

import com.sap.gateway.ip.core.customdev.util.Message;
import java.util.HashMap;
def Message processData(Message message) {
//body
def body = message.getBody()

//headers
def map = message.getHeaders()
def value = map.get(“x-forwarded-for”);
def splitterValues = value != null ? value.split(“,”): null
if(splitterValues != null && splitterValues.length > 0){
clientIP = splitterValues[splitterValues.length -1]
if(“xxx.xxx.xxx.xxx” == clientIP){
   throw new RuntimeException(“Request not allowed from IP address:” + clientIP + splitterValues)
   }
  }
return message
}

 

If there are multiple x-forwarded-for headers in the incoming request, then all the headers are consolidated into a single x-forwarded-for header with comma separated values ( e.g: 100.100.100,100,  xxx.xxx.xxx.xxx ).

Actual client IP address ( i.e, xxx.xxx.xxx.xxx) can be retrieved from the last value in the list as shown in the above mentioned script.

  •   For CXF-based Adapters ( IDoc and SOAP) ,the header values are returned as List of strings, hence the sample script looks slightly different than the above mentioned script.

import com.sap.gateway.ip.core.customdev.util.Message;
import java.util.HashMap;
def Message processData(Message message) {
//body
def body = message.getBody()

//headers
def map = message.getHeaders()
def value = map.get(“x-forwarded-for”);

boolean isContainingListOfIPs = value instanceof Collection

def clientActualIP = null
if(isContainingListOfIPs){
  //Get the last value from List
   clientActualIP = value.last()
   }else {
   clientActualIP = value
 }

if(clientActualIP != null){
     if(“xxx.xxx.xxx.xxx” == clientActualIP.trim()){
     throw new RuntimeException(“Request not allowed from IP address:” + clientActualIP)
     }
  }
  return message
}

 

Always remember to adjust and redeploy the Integration flow (Script) whenever there are network /IP address changes on the sender side.

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