---
title: tcpi_ecn_lost_syn
framework: Kernel
role: symbol
role_heading: Instance Property
platforms: [macOS 13.0+]
path: kernel/tcp_info/3944440-tcpi_ecn_lost_syn
---

# tcpi_ecn_lost_syn

## Declaration

```occ
u_int16_t tcpi_ecn_lost_syn:1;
```