---
title: NftMetaKey enum | Wartiva GraphQL API
description: NFTables meta key for packet metadata access. Wartiva GraphQL API reference with arguments, fields, and examples.
url: https://wartiva.com/api-docs/types/nft-meta-key.html
updated: 2026-10-07
---

Endpoint configuration · GraphQL enum

# `NftMetaKey` enum

NFTables meta key for packet metadata access. Used in meta expressions to match or set packet metadata such as interface name, mark, protocol, and packet routing information. Reference: [nftables — Matching packet metainformation](https://wiki.nftables.org/wiki-nftables/index.php/Matching_packet_metainformation)

## Values

| Enum Value | Description |
|---|---|
| `LEN` | Packet length in bytes (NFT_META_LEN). |
| `PROTOCOL` | Layer 2 ethertype protocol (NFT_META_PROTOCOL). |
| `PRIORITY` | TC packet priority/class ID (NFT_META_PRIORITY). |
| `MARK` | Packet mark / connection mark (NFT_META_MARK). |
| `IIF` | Input interface index (NFT_META_IIF). |
| `OIF` | Output interface index (NFT_META_OIF). |
| `IIFNAME` | Input interface name (NFT_META_IIFNAME). |
| `OIFNAME` | Output interface name (NFT_META_OIFNAME). |
| `IIFTYPE` | Input interface type (NFT_META_IIFTYPE). |
| `OIFTYPE` | Output interface type (NFT_META_OIFTYPE). |
| `SKUID` | Socket UID (NFT_META_SKUID). |
| `SKGID` | Socket GID (NFT_META_SKGID). |
| `NFTRACE` | Enable/disable packet tracing (NFT_META_NFTRACE). |
| `RTCLASSID` | Routing realm / class ID (NFT_META_RTCLASSID). |
| `SECMARK` | Security context mark (NFT_META_SECMARK). |
| `NFPROTO` | Netfilter protocol family (NFT_META_NFPROTO). |
| `L4PROTO` | Layer 4 protocol number (NFT_META_L4PROTO). |
| `BRIIIFNAME` | Bridge input interface name (NFT_META_BRI_IIFNAME). |
| `BRIOIFNAME` | Bridge output interface name (NFT_META_BRI_OIFNAME). |
| `PKTTYPE` | Packet type (unicast, broadcast, multicast) (NFT_META_PKTTYPE). |
| `CPU` | CPU number the packet is being processed on (NFT_META_CPU). |
| `IIFGROUP` | Input interface group (NFT_META_IIFGROUP). |
| `OIFGROUP` | Output interface group (NFT_META_OIFGROUP). |
| `CGROUP` | Control group v1 classID (NFT_META_CGROUP). |
| `PRANDOM` | Pseudo-random number (NFT_META_PRANDOM). |

## Used by

- [`MetaExpression`](https://wartiva.com/api-docs/types/meta-expression.html) type: MetaExpression represents an nftables expression for accessing meta-data about the packet, the network device, or the system context.

## Example

### Example

```json
"LEN"

```

---

Wartiva is in early access. Request access: https://wartiva.com/early-access.html  
All pages: https://wartiva.com/llms.txt