---
title: FibExpression type | Wartiva GraphQL API
description: Fib represents an nftables expression for performing a Forwarding Information Base (FIB) lookup. Wartiva GraphQL API reference with arguments, fields, and examples.
url: https://wartiva.com/api-docs/types/fib-expression.html
updated: 2026-10-07
---

Endpoint configuration · GraphQL type

# `FibExpression` type

Fib represents an nftables expression for performing a Forwarding Information Base (FIB) lookup. This allows rules to query the kernel's routing table based on specified flags and store a particular result.

## Fields

| Field Name | Description |
|---|---|
| `register` - [`NftRegister!`](https://wartiva.com/api-docs/types/nft-register.html) | The register where the result of the FIB lookup will be stored. |
| `result` - [`FibResult!`](https://wartiva.com/api-docs/types/fib-result.html) | The specific result to retrieve from the FIB lookup (e.g., output interface, address type). |
| `flags` - [`[FibFlag!]`](https://wartiva.com/api-docs/types/fib-flag.html) | The flag specifying the criteria to use for the FIB lookup (e.g., source address, destination address). |

## Used by

- [`ChainExpression`](https://wartiva.com/api-docs/types/chain-expression.html) union: A union of all possible nftables chain expression types.

## Example

### Example

```json
{"register": "VERDICT", "result": "OIF", "flags": ["SADDR"]}

```

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