---
name: "CURLOPT_TFTP_BLKSIZE"
section: "3"
platform: "macos"
package: "curl"
version: "166.0.0.0.1"
release: "macOS 26.5"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_TFTP_BLKSIZE"
---

# CURLOPT\_TFTP\_BLKSIZE(3)

TFTP block size

## NAME

CURLOPT\_TFTP\_BLKSIZE - TFTP block size

## SYNOPSIS

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_TFTP_BLKSIZE, long blocksize);
```

## DESCRIPTION

Specify *blocksize* to use for TFTP data transmission. Valid range as per RFC 2348 is 8-65464 bytes. The default of 512 bytes is used if this option is not specified. The specified block size is only used if supported by the remote server. If the server does not return an option acknowledgment or returns an option acknowledgment with no block size, the default of 512 bytes is used.

## DEFAULT

512

## PROTOCOLS

TFTP

## EXAMPLE

```
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "tftp://example.com/bootimage");
    /* try using larger blocks */
    curl_easy_setopt(curl, CURLOPT_TFTP_BLKSIZE, 2048L);
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
```

## AVAILABILITY

Added in 7.19.4

## RETURN VALUE

Returns CURLE\_OK if the option is supported, and CURLE\_UNKNOWN\_OPTION if not.

## SEE ALSO

[**CURLOPT\_MAXFILESIZE**(3)](/CURLOPT_MAXFILESIZE/3.md)