---
name: "nfq_tcp_compute_checksum_ipv4"
section: "3"
platform: "linux"
package: "libnetfilter-queue-doc"
version: "1.0.5-4"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/nfq_tcp_compute_checksum_ipv4"
---

# nfq\_tcp\_compute\_checksum\_ipv4(3)

Internal TCP functions

## NAME

tcp\_internals - Internal TCP functions

## SYNOPSIS

### Functions

void **nfq\_tcp\_compute\_checksum\_ipv4** (struct tcphdr \*tcph, struct iphdr \*iph)\
 void **nfq\_tcp\_compute\_checksum\_ipv6** (struct tcphdr \*tcph, struct ip6\_hdr \*ip6h)\

## Detailed Description

Most user-space programs will never need these.

## Function Documentation

### void nfq\_tcp\_compute\_checksum\_ipv4 (struct tcphdr \* tcph, struct iphdr \* iph)

nfq\_tcp\_compute\_checksum\_ipv4 - computes IPv4/TCP packet checksum

**Parameters**

*tcph* pointer to the TCP header \
 *iph* pointer to the IPv4 header

**Note**

**nfq\_tcp\_mangle\_ipv4()** invokes this function. As long as developers always use **nfq\_tcp\_mangle\_ipv4** when changing the content of a TCP message, there is no need to call **nfq\_tcp\_compute\_checksum\_ipv4**.

Definition at line **108** of file **tcp.c**.

### void nfq\_tcp\_compute\_checksum\_ipv6 (struct tcphdr \* tcph, struct ip6\_hdr \* ip6h)

nfq\_tcp\_compute\_checksum\_ipv6 - computes IPv6/TCP packet checksum

**Parameters**

*tcph* pointer to the TCP header \
 *ip6h* pointer to the IPv6 header

**Note**

**nfq\_tcp\_mangle\_ipv6()** invokes this function. As long as developers always use **nfq\_tcp\_mangle\_ipv6** when changing the content of a TCP message, there is no need to call **nfq\_tcp\_compute\_checksum\_ipv6**.

Definition at line **126** of file **tcp.c**.

## Author

Generated automatically by Doxygen for libnetfilter\_queue from the source code.