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/*
* ProFTPD - mod_sftp traffic analysis protection
* Copyright (c) 2008-2011 TJ Saunders
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA.
*
* As a special exemption, TJ Saunders and other respective copyright holders
* give permission to link this program with OpenSSL, and distribute the
* resulting executable, without including the source code for OpenSSL in the
* source distribution.
*
* $Id: tap.h,v 1.6 2011/05/23 20:40:13 castaglia Exp $
*/
#include "mod_sftp.h"
#ifndef MOD_SFTP_TAP_H
#define MOD_SFTP_TAP_H
int sftp_tap_have_policy(const char *);
/* May send an SSH2_MSG_IGNORE packet of random length, filled with random
* data to the client, depending on the selected policy. These messages can
* be injected into the SSH session in order to make traffic analysis harder.
* Returns -1 if there was an error while sending the packet, zero otherwise.
*/
int sftp_tap_send_packet(void);
/* Sets the traffic analysis protection (TAP) policy. Returns 0 if the given
* policy is acceptable, -1 otherwise.
*
* The list of policies is:
*
* "none" - send no SSH2_MSG_IGNORE packets
*
* "low" - 1 in 1000 chance of sending SSH2_MSG_IGNORE, with lengths of
* 64 to 256 bytes of random data.
*
* "medium" - 1 in 100 chance of sending SSH2_MSG_IGNORE, with lengths of
* 32 to 768 bytes of random data.
*
* "high" - 1 in 10 chance of sending SSH2_MSG_IGNORE, with lengths of
* 16 to 2048 bytes of random data.
*
* "paranoid" - always send SSH2_MSG_IGNORE packets, of lengths up to 8KB.
*
* Note that there is an additional TAP policy called 'rogaway'. This
* policy is automatically used if the negotiated server-to-client cipher
* is any of the CBC ciphers. The purpose of the 'rogaway' TAP policy is
* to implement the mitigation of the Rogaway CBC mode attack (see RFC4251,
* Section 9.3.1) via the use of IGNORE packets. The use of the 'rogaway'
* policy is hardcoded, and will override any configured TAP policy.
*/
int sftp_tap_set_policy(const char *);
#endif
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