---
name: "gnutls_dtls_set_data_mtu"
section: "3"
platform: "linux"
package: "gnutls"
version: "3.8.13-3"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/gnutls_dtls_set_data_mtu"
---

# gnutls\_dtls\_set\_data\_mtu(3)

API function

## NAME

gnutls\_dtls\_set\_data\_mtu - API function

## SYNOPSIS

**#include \<gnutls/dtls.h\>**

**int gnutls\_dtls\_set\_data\_mtu(gnutls\_session\_t** *session***, unsigned int** *mtu***);**

## ARGUMENTS

- gnutls\_session\_t session

  is a **gnutls\_session\_t** type.

- unsigned int mtu

  The maximum unencrypted transfer unit of the session

## DESCRIPTION

This function will set the maximum size of the \*unencrypted\* records which will be sent over a DTLS session. It is equivalent to calculating the DTLS packet overhead with the current encryption parameters, and calling **gnutls\_dtls\_set\_mtu()** with that value. In particular, this means that you may need to call this function again after any negotiation or renegotiation, in order to ensure that the MTU is still sufficient to account for the new protocol overhead.

In most cases you only need to call **gnutls\_dtls\_set\_mtu()** with the maximum MTU of your transport layer.

## RETURNS

**GNUTLS\_E\_SUCCESS** (0) on success, or a negative error code.

## SINCE

3\.1

## REPORTING BUGS

Report bugs to \<bugs@gnutls.org\>.\
 Home page: https://www.gnutls.org

## COPYRIGHT

Copyright © 2001-2023 Free Software Foundation, Inc., and others.\
 Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved.

## SEE ALSO

The full documentation for **gnutls** is maintained as a Texinfo manual. If the /usr/share/doc/gnutls/ directory does not contain the HTML form visit

- https://www.gnutls.org/manual/