---
name: "dnsjit.core.object.tcp"
section: "3"
platform: "linux"
package: "dnsjit"
version: "1.5.0-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/dnsjit.core.object.tcp"
---

# dnsjit.core.object.tcp(3)

A TCP segment header

## NAME

dnsjit.core.object.tcp - A TCP segment header

## DESCRIPTION

A TCP segment header. The data itself is in the *dnsjit.core.object.payload* object, which is the next object in the chain after parsing with, for example, *dnsjit.filter.layer*.

### Attributes

- sport

  Source port.

- dport

  Destination port.

- seq

  Sequence number.

- ack

  Acknowledgement number.

- off

  Data offset.

- x2

  Unused.

- flags

  TCP flags.

- win

  Window.

- sum

  Checksum.

- urp

  Urgent pointer.

- opts

  Array of bytes with the TCP options found.

- opts\_len

  Length of the TCP options.

### Functions

- **Tcp:type**()

  Return the textual type of the object.

- **Tcp:prev**()

  Return the previous object.

- **Tcp:cast**()

  Cast the object to the underlining object module and return it.

- **Tcp:uncast**()

  Cast the object to the generic object module and return it.

- **Tcp:copy**()

  Make a copy of the object and return it.

- **Tcp:free**()

  Free the object, should only be used on copies or otherwise allocated.

## SEE ALSO

[**dnsjit.core.object**(3)](/dnsjit.core.object/3.md), [**dnsjit.core.object.payload**(3)](/dnsjit.core.object.payload/3.md), [**dnsjit.filter.layer**(3)](/dnsjit.filter.layer/3.md)

## AUTHORS and CONTRIBUTORS

Jerry Lundström (DNS-OARC), Tomáš Křížek (CZ.NIC), Petr Špaček (ISC)

Maintained by DNS-OARC

*https://www.dns-oarc.net/*

## BUGS

For issues and feature requests please use:

*https://github.com/DNS-OARC/dnsjit/issues*

For question and help please use:

*admin@dns-oarc.net*