# Ensure nftables Base Chains Exist

- Source: https://support.icompaas.com/support/solutions/articles/62000235364-ensure-nftables-base-chains-exist
- Section: [Solutions](https://support.icompaas.com/support/solutions) › [CIS Amazon Linux 2 Benchmark v3.0.0](https://support.icompaas.com/support/solutions/62000112696) › [CIS Amazon Linux 2 Benchmarks](https://support.icompaas.com/support/solutions/folders/62000169265)
- Last updated: 2026-05-29
- Publisher: iCompaas, Inc. (https://www.icompaas.com)

**Profile Applicability:** • Level 1

**Description:** Base chains in nftables are the fundamental chains (such as input, forward, and output) within a table that process network traffic. Ensuring these base chains exist is essential for proper firewall operation and effective packet filtering.

**Rationale:** Presence of base chains guarantees that nftables can enforce firewall policies on incoming, outgoing, and forwarded packets, thereby securing the system’s network traffic.

**Impact:** Pros:

-   Enables structured and efficient firewall rule processing.  
    
-   Supports comprehensive network traffic filtering.  
    

Cons:

-   Missing base chains may leave traffic unfiltered, increasing risk.  
    

**Default Value:** No base chains exist by default until configured.

**Pre-requisites:**

-   Root or sudo privileges to query and modify nftables.  
    

**Remediation:**

### **Test Plan:**

**Using Linux command line:**

1\. List nftables chains in the relevant table (e.g., inet filter):  

nft list table inet filter

2\. Verify presence of base chains: input, forward, and output.  

### **Implementation Plan:**

**Using Linux command line:**

1\. Create base chains if missing, for example:  

nft add chain inet filter input { type filter hook input priority 0 \\; }  
nft add chain inet filter forward { type filter hook forward priority 0 \\; }  
nft add chain inet filter output { type filter hook output priority 0 \\; }

2\. Verify chains creation:  

nft list table inet filter

### **Backout Plan:**

**Using Linux command line:**

1\. Delete base chains if necessary:  

nft delete chain inet filter input  
nft delete chain inet filter forward  
nft delete chain inet filter output

2\. Confirm deletion:  

nft list table inet filter

**References:**

-   CIS Amazon Linux 2 Benchmark v3.0.0  
    
-   nftables Documentation  
    
-   [NIST SP 800-53 Revision 5 - SC-7  
    ](https://csrc.nist.gov/publications/detail/sp/800-53/rev-5/final#sc-7)

## Related compliance guidance

- [SOC 2 compliance: a practical implementation guide for cloud-native SaaS teams](https://support.icompaas.com/compliance/soc-2-trust-services-criteria): Configuration checks like this one are the technical half of a SOC 2 / ISO 27001 programme — the guide shows where they fit, what else an auditor expects, and how to evidence them.
- [ISO/IEC 27001:2022 compliance: a practical implementation guide](https://support.icompaas.com/compliance/iso-27001-2022): ISO 27001 Annex A.8 (technological controls) is where cloud hardening evidence lands; the guide shows how to run the ISMS around it.