Mercurial > dropbear
view agentfwd.h @ 1790:42745af83b7d
Introduce extra delay before closing unauthenticated sessions
To make it harder for attackers, introduce a delay to keep an
unauthenticated session open a bit longer, thus blocking a connection
slot until after the delay.
Without this, while there is a limit on the amount of attempts an attacker
can make at the same time (MAX_UNAUTH_PER_IP), the time taken by dropbear to
handle one attempt is still short and thus for each of the allowed parallel
attempts many attempts can be chained one after the other. The attempt rate
is then:
"MAX_UNAUTH_PER_IP / <process time of one attempt>".
With the delay, this rate becomes:
"MAX_UNAUTH_PER_IP / UNAUTH_CLOSE_DELAY".
author | Thomas De Schampheleire <thomas.de_schampheleire@nokia.com> |
---|---|
date | Wed, 15 Feb 2017 13:53:04 +0100 |
parents | a53e7d2d60be |
children |
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/* * Dropbear - a SSH2 server * * Copyright (c) 2002,2003 Matt Johnston * All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ #ifndef DROPBEAR_AGENTFWD_H_ #define DROPBEAR_AGENTFWD_H_ #include "includes.h" #include "chansession.h" #include "channel.h" #include "auth.h" #include "list.h" #if DROPBEAR_CLI_AGENTFWD /* From OpenSSH authfd.h */ #define SSH_AGENT_RSA_SHA2_256 0x02 /* An agent reply can be reasonably large, as it can * contain a list of all public keys held by the agent. * 10000 is arbitrary */ #define MAX_AGENT_REPLY 10000 /* client functions */ void cli_load_agent_keys(m_list * ret_list); void agent_buf_sign(buffer *sigblob, sign_key *key, const buffer *data_buf, enum signature_type type); void cli_setup_agent(const struct Channel *channel); #ifdef __hpux #define seteuid(a) setresuid(-1, (a), -1) #define setegid(a) setresgid(-1, (a), -1) #endif extern const struct ChanType cli_chan_agent; #endif /* DROPBEAR_CLI_AGENTFWD */ #if DROPBEAR_SVR_AGENTFWD int svr_agentreq(struct ChanSess * chansess); void svr_agentcleanup(struct ChanSess * chansess); void svr_agentset(const struct ChanSess *chansess); #endif /* DROPBEAR_SVR_AGENTFWD */ #endif /* DROPBEAR_AGENTFWD_H_ */