---
title: ExthdrExpression type | Wartiva GraphQL API
description: Exthdr represents an nftables expression for accessing or manipulating IPv6 extension headers, TCP options, or other protocol options.
url: https://wartiva.com/api-docs/types/exthdr-expression.html
updated: 2026-10-07
---

Endpoint configuration · GraphQL type

# `ExthdrExpression` type

Exthdr represents an nftables expression for accessing or manipulating IPv6 extension headers, TCP options, or other protocol options.

## Fields

| Field Name | Description |
|---|---|
| `destRegister` - [`NftRegister!`](https://wartiva.com/api-docs/types/nft-register.html) | The register where the result of the extended header operation will be stored. |
| `type` - [`Int!`](https://wartiva.com/api-docs/types/int.html) | The type of the extended header or option to inspect/manipulate (e.g., AH, ESP, HOPOPT for IPv6), returned as an unsigned 8-bit integer. |
| `offset` - [`Uint32!`](https://wartiva.com/api-docs/types/uint32.html) | The byte offset within the extended header or option to start reading from. |
| `len` - [`Uint32!`](https://wartiva.com/api-docs/types/uint32.html) | The length in bytes of the data to read from the extended header or option. |
| `flags` - [`ExthdrFlags!`](https://wartiva.com/api-docs/types/exthdr-flags.html) | Flags associated with the extended header operation, e.g., to check for presence. |
| `op` - [`ExthdrOperation!`](https://wartiva.com/api-docs/types/exthdr-operation.html) | The specific protocol or context for the extended header operation (e.g., IPv6, TCP). |
| `sourceRegister` - [`NftRegister!`](https://wartiva.com/api-docs/types/nft-register.html) | The register holding the input value if required by the operation. |

## 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
{
  "destRegister": "VERDICT",
  "type": 987,
  "offset": "1073741824",
  "len": "1073741824",
  "flags": "PRESENT",
  "op": "IPV6",
  "sourceRegister": "VERDICT"
}

```

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