# Source: https://docs.datadoghq.com/security/default_rules/1a5-552-53d.md

---
title: Inbound RPC access should be restricted
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: Docs > Datadog Security > OOTB Rules > Inbound RPC access should be restricted
---

# Inbound RPC access should be restricted
 
## Description{% #description %}

Reduce the probability of a breach by checking [EC2 security groups](https://docs.aws.amazon.com/vpc/latest/userguide/VPC_SecurityGroups.html) for inbound rules that allow unfettered access to TCP port 135 (used by Microsoft Message Queuing (MSMQ) and other Windows software) and restrict access to IP addresses that require this port.

## Rationale{% #rationale %}

Malicious activity, such as backdoor command shell hacking and denial-of-service (DoS) attacks, can occur when permitting unfettered access to this port.

## Remediation{% #remediation %}

### From the console{% #from-the-console %}

Follow the [Security group rules](https://docs.aws.amazon.com/vpc/latest/userguide/VPC_SecurityGroups.html#SecurityGroupRules) docs to learn how to add a security group rule that will restrict access to a specific port.

### From the command line{% #from-the-command-line %}

1. Run `revoke-security-group-ingress` to [remove inbound rules](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ec2/revoke-security-group-ingress.html) that allow unrestricted access to port 135.

In the `revoke-security-group-ingress.sh` file:

   ```bash
       aws ec2 revoke-security-group-ingress
           --group-name group-name
           --protocol tcp
           --port 135
           --cidr 192.0.2.0/24
       
```

1. Run `authorize-security-group-ingress` to [add new inbound rules](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ec2/authorize-security-group-ingress.html) that restrict port 135 access.

In the `revoke-security-group-ingress.sh` file:

   ```bash
       aws ec2 authorize-security-group-ingress
           --group-name your-group-name
           --protocol tcp
           --port 135
           --cidr 192.0.2.0/24
       
```