May 17, 2005 KRB5_AUTH_CONTEXT 3

### NAME

krb5_auth_con_addflags, krb5_auth_con_free, krb5_auth_con_genaddrs, krb5_auth_con_generatelocalsubkey, krb5_auth_con_getaddrs, krb5_auth_con_getauthenticator, krb5_auth_con_getflags, krb5_auth_con_getkey, krb5_auth_con_getlocalsubkey, krb5_auth_con_getrcache, krb5_auth_con_getremotesubkey, krb5_auth_con_getuserkey, krb5_auth_con_init, krb5_auth_con_initivector, krb5_auth_con_removeflags, krb5_auth_con_setaddrs, krb5_auth_con_setaddrs_from_fd, krb5_auth_con_setflags, krb5_auth_con_setivector, krb5_auth_con_setkey, krb5_auth_con_setlocalsubkey, krb5_auth_con_setrcache, krb5_auth_con_setremotesubkey, krb5_auth_con_setuserkey, krb5_auth_context, krb5_auth_getcksumtype, krb5_auth_getkeytype, krb5_auth_getlocalseqnumber, krb5_auth_getremoteseqnumber, krb5_auth_setcksumtype, krb5_auth_setkeytype, krb5_auth_setlocalseqnumber, krb5_auth_setremoteseqnumber, krb5_free_authenticator - manage authentication on connection level

### LIBRARY

Kerberos 5 Library (libkrb5, -lkrb5)

### SYNOPSIS

```krb5_error_code` krb5_auth_con_init(`` ```krb5_context context` ```krb5_auth_context *auth_context` )
```void` krb5_auth_con_free(`` ```krb5_context context` ```krb5_auth_context auth_context` )
```krb5_error_code` krb5_auth_con_setflags(`` ```krb5_context context` ```krb5_auth_context auth_context` ```int32_t flags` )
```krb5_error_code` krb5_auth_con_getflags(`` ```krb5_context context` ```krb5_auth_context auth_context` ```int32_t *flags` )
```krb5_error_code` krb5_auth_con_addflags(`` ```krb5_context context` ```krb5_auth_context auth_context` ```int32_t addflags` ```int32_t *flags` )
```krb5_error_code` krb5_auth_con_removeflags(`` ```krb5_context context` ```krb5_auth_context auth_context` ```int32_t removelags` ```int32_t *flags` )
```krb5_error_code` krb5_auth_con_setaddrs(`` ```krb5_context context` ```krb5_auth_context auth_context` ```krb5_address *local_addr` ```krb5_address *remote_addr` )
```krb5_error_code` krb5_auth_con_getaddrs(`` ```krb5_context context` ```krb5_auth_context auth_context` ```krb5_address **local_addr` ```krb5_address **remote_addr` )
```krb5_error_code` krb5_auth_con_genaddrs(`` ```krb5_context context` ```krb5_auth_context auth_context` ```int fd` ```int flags` )
```krb5_error_code` krb5_auth_con_setaddrs_from_fd(`` ```krb5_context context` ```krb5_auth_context auth_context` ```void *p_fd` )
```krb5_error_code` krb5_auth_con_getkey(`` ```krb5_context context` ```krb5_auth_context auth_context` ```krb5_keyblock **keyblock` )
```krb5_error_code` krb5_auth_con_getlocalsubkey(`` ```krb5_context context` ```krb5_auth_context auth_context` ```krb5_keyblock **keyblock` )
```krb5_error_code` krb5_auth_con_getremotesubkey(`` ```krb5_context context` ```krb5_auth_context auth_context` ```krb5_keyblock **keyblock` )
```krb5_error_code` krb5_auth_con_generatelocalsubkey(`` ```krb5_context context` ```krb5_auth_context auth_context` ```krb5_keyblock``*key"` )
```krb5_error_code` krb5_auth_con_initivector(`` ```krb5_context context` ```krb5_auth_context auth_context` )
```krb5_error_code` krb5_auth_con_setivector(`` ```krb5_context context` ```krb5_auth_context *auth_context` ```krb5_pointer ivector` )
```void` krb5_free_authenticator(`` ```krb5_context context` ```krb5_authenticator *authenticator` )

### DESCRIPTION

The krb5_auth_context structure holds all context related to an authenticated connection, in a similar way to krb5_context that holds the context for the thread or process. krb5_auth_context is used by various functions that are directly related to authentication between the server/client. Example of data that this structure contains are various flags, addresses of client and server, port numbers, keyblocks (and subkeys), sequence numbers, replay cache, and checksum-type.

krb5_auth_con_init(``) allocates and initializes the krb5_auth_context structure. Default values can be changed with krb5_auth_con_setcksumtype(``) and krb5_auth_con_setflags(``). The auth_context structure must be freed by krb5_auth_con_free(``).

krb5_auth_con_getflags(``), krb5_auth_con_setflags(``), krb5_auth_con_addflags(``) and krb5_auth_con_removeflags(``) gets and modifies the flags for a krb5_auth_context structure. Possible flags to set are:

```KRB5_AUTH_CONTEXT_DO_SEQUENCE`
  Generate and check sequence-number on each packet.

```KRB5_AUTH_CONTEXT_DO_TIME`
  Check timestamp on incoming packets.

```KRB5_AUTH_CONTEXT_RET_SEQUENCE```,`KRB5_AUTH_CONTEXT_RET_TIME`
  Return sequence numbers and time stamps in the outdata parameters.

```KRB5_AUTH_CONTEXT_CLEAR_FORWARDED_CRED`
  will force krb5_get_forwarded_creds(``) and krb5_fwd_tgt_creds(``) to create unencrypted ) ```ENCTYPE_NULL`) credentials. This is for use with old MIT server and JAVA based servers as they can't handle encrypted ```KRB-CRED`. Note that sending such ```KRB-CRED` is clear exposes crypto keys and tickets and is insecure, make sure the packet is encrypted in the protocol. krb5_rd_cred(3), krb5_rd_priv(3), krb5_rd_safe(3), krb5_mk_priv(3) and krb5_mk_safe(3). Setting this flag requires that parameter to be passed to these functions.

  The flags ```KRB5_AUTH_CONTEXT_DO_TIME` also modifies the behavior the function krb5_get_forwarded_creds(``) by removing the timestamp in the forward credential message, this have backward compatibility problems since not all versions of the heimdal supports timeless credentional messages. Is very useful since it always the sender of the message to cache forward message and thus avoiding a round trip to the KDC for each time a credential is forwarded. The same functionality can be obtained by using address-less tickets.

krb5_auth_con_setaddrs(``), krb5_auth_con_setaddrs_from_fd(``) and krb5_auth_con_getaddrs(``) gets and sets the addresses that are checked when a packet is received. It is mandatory to set an address for the remote host. If the local address is not set, it iss deduced from the underlaying operating system. krb5_auth_con_getaddrs(``) will call krb5_free_address(``) on any address that is passed in ```local_addr` or ```remote_addr`. krb5_auth_con_setaddr(``) allows passing in a ```NULL` pointer as ```local_addr` and ```remote_addr`, in that case it will just not set that address.

krb5_auth_con_setaddrs_from_fd(``) fetches the addresses from a file descriptor.

krb5_auth_con_genaddrs(``) fetches the address information from the given file descriptor ```fd` depending on the bitmap argument ```flags`.

Possible values on ```flags` are:

KRB5_AUTH_CONTEXT_GENERATE_LOCAL_ADDR
  fetches the local address from ```fd`.

KRB5_AUTH_CONTEXT_GENERATE_REMOTE_ADDR
  fetches the remote address from ```fd`.

krb5_auth_con_setkey(``), krb5_auth_con_setuserkey(``) and krb5_auth_con_getkey(``) gets and sets the key used for this auth context. The keyblock returned by krb5_auth_con_getkey(``) should be freed with krb5_free_keyblock(``). The keyblock send into krb5_auth_con_setkey(``) is copied into the krb5_auth_context, and thus no special handling is needed. ```NULL` is not a valid keyblock to krb5_auth_con_setkey(``).

krb5_auth_con_setuserkey(``) is only useful when doing user to user authentication. krb5_auth_con_setkey(``) is equivalent to krb5_auth_con_setuserkey(``).

krb5_auth_con_getlocalsubkey(``), krb5_auth_con_setlocalsubkey(``), krb5_auth_con_getremotesubkey(``) and krb5_auth_con_setremotesubkey(``) gets and sets the keyblock for the local and remote subkey. The keyblock returned by krb5_auth_con_getlocalsubkey(``) and krb5_auth_con_getremotesubkey(``) must be freed with krb5_free_keyblock(``).

krb5_auth_setcksumtype(``) and krb5_auth_getcksumtype(``) sets and gets the checksum type that should be used for this connection.

krb5_auth_con_generatelocalsubkey(``) generates a local subkey that have the same encryption type as ```key`.

krb5_auth_getremoteseqnumber(``) krb5_auth_setremoteseqnumber(``), krb5_auth_getlocalseqnumber(``) and krb5_auth_setlocalseqnumber(``) gets and sets the sequence-number for the local and remote sequence-number counter.

krb5_auth_setkeytype(``) and krb5_auth_getkeytype(``) gets and gets the keytype of the keyblock in krb5_auth_context.

krb5_auth_con_getauthenticator(``) Retrieves the authenticator that was used during mutual authentication. The ```authenticator` returned should be freed by calling krb5_free_authenticator(``).

krb5_auth_con_getrcache(``) and krb5_auth_con_setrcache(``) gets and sets the replay-cache.

krb5_auth_con_initivector(``) allocates memory for and zeros the initial vector in the ```auth_context` keyblock.

krb5_auth_con_setivector(``) sets the i_vector portion of ```auth_context` to ```ivector`.

krb5_free_authenticator(``) free the content of ```authenticator` and ```authenticator` itself.

### SEE ALSO

krb5_context(3), kerberos(8)