---
name: "libssh2_knownhost_add"
section: "3"
platform: "linux"
package: "libssh2"
version: "1.11.1-7"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/libssh2_knownhost_add"
---

# libssh2\_knownhost\_add(3)

add a known host

## NAME

libssh2\_knownhost\_add - add a known host

## SYNOPSIS

```
#include <libssh2.h>
int
libssh2_knownhost_add(LIBSSH2_KNOWNHOSTS *hosts,
                      char *host, char *salt,
                      char *key, size_t keylen,
                      int typemask,
                      struct libssh2_knownhost **store);
```

## DESCRIPTION

We discourage use of this function as of libssh2 1.2.5. Instead we strongly urge users to use *[libssh2\_knownhost\_addc(3)](/libssh2_knownhost_addc/3.md)* instead, which as a more complete API. *[libssh2\_knownhost\_add(3)](/libssh2_knownhost_add/3.md)* is subject for removal in a future release.

Adds a known host to the collection of known hosts identified by the 'hosts' handle.

*host* is a pointer the host name in plain text or hashed. If hashed, it must be provided base64 encoded. The host name can be the IP numerical address of the host or the full name.

*saltP is a pointer to the salt used for the host hashing, if the host is* *provided hashed. If the host is provided in plain text, salt has no meaning.* *The salt has to be provided base64 encoded with a trailing zero byte.*

*key is a pointer to the key for the given host.*

*keylen is the total size in bytes of the key pointed to by the key* *argument*

*typemask is a bitmask that specifies format and info about the data* *passed to this function. Specifically, it details what format the host name is,* *what format the key is and what key type it is.*

*The host name is given as one of the following types:* *LIBSSH2\_KNOWNHOST\_TYPE\_PLAIN, LIBSSH2\_KNOWNHOST\_TYPE\_SHA1 or* *LIBSSH2\_KNOWNHOST\_TYPE\_CUSTOM.*

*The key is encoded using one of the following encodings:* *LIBSSH2\_KNOWNHOST\_KEYENC\_RAW or LIBSSH2\_KNOWNHOST\_KEYENC\_BASE64.*

*The key is using one of these algorithms:* *LIBSSH2\_KNOWNHOST\_KEY\_RSA1, LIBSSH2\_KNOWNHOST\_KEY\_SSHRSA or* *LIBSSH2\_KNOWNHOST\_KEY\_SSHDSS (deprecated).*

*store should point to a pointer that gets filled in to point to the* *known host data after the addition. NULL can be passed if you do not care about* *this pointer.*

## RETURN VALUE

*Returns a regular libssh2 error code, where negative values are error codes* *and 0 indicates success.*

## AVAILABILITY

*Added in libssh2 1.2, deprecated since libssh2 1.2.5. Use* *[libssh2\_knownhost\_addc(3)](/libssh2_knownhost_addc/3.md) instead!*

## SEE ALSO

**[libssh2\_knownhost\_init(3)](/libssh2_knownhost_init/3.md)** **[libssh2\_knownhost\_free(3)](/libssh2_knownhost_free/3.md)** **[libssh2\_knownhost\_check(3)](/libssh2_knownhost_check/3.md)** **[libssh2\_knownhost\_addc(3)](/libssh2_knownhost_addc/3.md)**