SSH2: send KEXINIT packet and identification string first or last
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terrafrost
parent
acebfe28d6
commit
7ccb0d0b02
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@ -875,6 +875,22 @@ class Net_SSH2
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*/
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var $agent;
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/**
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* Send the identification string first?
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*
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* @var bool
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* @access private
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*/
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var $send_id_string_first = true;
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/**
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* Send the key exchange initiation packet first?
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*
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* @var bool
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* @access private
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*/
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var $send_kex_first = true;
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/**
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* Default Constructor.
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*
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@ -1017,13 +1033,69 @@ class Net_SSH2
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* CRYPT_MODE_INTERNAL, CRYPT_MODE_MCRYPT
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*
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* @param int $engine
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* @access private
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* @access public
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*/
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function setCryptoEngine($engine)
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{
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$this->crypto_engine = $engine;
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}
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/**
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* Send Identification String First
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*
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* https://tools.ietf.org/html/rfc4253#section-4.2 says "when the connection has been established,
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* both sides MUST send an identification string". It does not say which side sends it first. In
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* theory it shouldn't matter but it is a fact of life that some SSH servers are simply buggy
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*
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* @access public
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*/
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function sendIdentificationStringFirst()
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{
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$this->send_id_string_first = true;
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}
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/**
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* Send Identification String Last
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*
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* https://tools.ietf.org/html/rfc4253#section-4.2 says "when the connection has been established,
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* both sides MUST send an identification string". It does not say which side sends it first. In
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* theory it shouldn't matter but it is a fact of life that some SSH servers are simply buggy
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*
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* @access public
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*/
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function sendIdentificationStringLast()
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{
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$this->send_id_string_first = false;
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}
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/**
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* Send SSH_MSG_KEXINIT First
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*
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* https://tools.ietf.org/html/rfc4253#section-7.1 says "key exchange begins by each sending
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* sending the [SSH_MSG_KEXINIT] packet". It does not say which side sends it first. In theory
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* it shouldn't matter but it is a fact of life that some SSH servers are simply buggy
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*
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* @access public
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*/
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function sendKEXINITFirst()
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{
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$this->send_kex_first = true;
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}
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/**
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* Send SSH_MSG_KEXINIT Last
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*
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* https://tools.ietf.org/html/rfc4253#section-7.1 says "key exchange begins by each sending
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* sending the [SSH_MSG_KEXINIT] packet". It does not say which side sends it first. In theory
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* it shouldn't matter but it is a fact of life that some SSH servers are simply buggy
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*
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* @access public
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*/
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function sendKEXINITLast()
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{
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$this->send_kex_first = false;
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}
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/**
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* Connect to an SSHv2 server
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*
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@ -1065,7 +1137,9 @@ class Net_SSH2
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$this->identifier = $this->_generate_identifier();
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fputs($this->fsock, $this->identifier . "\r\n");
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if ($this->send_id_string_first) {
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fputs($this->fsock, $this->identifier . "\r\n");
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}
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/* According to the SSH2 specs,
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@ -1125,18 +1199,28 @@ class Net_SSH2
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return false;
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}
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$response = $this->_get_binary_packet();
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if ($response === false) {
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user_error('Connection closed by server');
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return false;
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if (!$this->send_id_string_first) {
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fputs($this->fsock, $this->identifier . "\r\n");
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}
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if (!strlen($response) || ord($response[0]) != NET_SSH2_MSG_KEXINIT) {
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user_error('Expected SSH_MSG_KEXINIT');
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return false;
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if (!$this->send_kex_first) {
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$response = $this->_get_binary_packet();
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if ($response === false) {
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user_error('Connection closed by server');
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return false;
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}
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if (!strlen($response) || ord($response[0]) != NET_SSH2_MSG_KEXINIT) {
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user_error('Expected SSH_MSG_KEXINIT');
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return false;
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}
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if (!$this->_key_exchange($response)) {
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return false;
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}
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}
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if (!$this->_key_exchange($response)) {
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if ($this->send_kex_first && !$this->_key_exchange()) {
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return false;
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}
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@ -1180,10 +1264,10 @@ class Net_SSH2
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/**
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* Key Exchange
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*
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* @param string $kexinit_payload_server
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* @param string $kexinit_payload_server optional
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* @access private
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*/
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function _key_exchange($kexinit_payload_server)
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function _key_exchange($kexinit_payload_server = false)
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{
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static $kex_algorithms = array(
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'diffie-hellman-group1-sha1', // REQUIRED
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@ -1317,6 +1401,51 @@ class Net_SSH2
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$client_cookie = crypt_random_string(16);
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$kexinit_payload_client = pack(
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'Ca*Na*Na*Na*Na*Na*Na*Na*Na*Na*Na*CN',
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NET_SSH2_MSG_KEXINIT,
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$client_cookie,
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strlen($str_kex_algorithms),
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$str_kex_algorithms,
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strlen($str_server_host_key_algorithms),
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$str_server_host_key_algorithms,
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strlen($encryption_algorithms_client_to_server),
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$encryption_algorithms_client_to_server,
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strlen($encryption_algorithms_server_to_client),
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$encryption_algorithms_server_to_client,
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strlen($mac_algorithms_client_to_server),
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$mac_algorithms_client_to_server,
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strlen($mac_algorithms_server_to_client),
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$mac_algorithms_server_to_client,
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strlen($compression_algorithms_client_to_server),
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$compression_algorithms_client_to_server,
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strlen($compression_algorithms_server_to_client),
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$compression_algorithms_server_to_client,
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0,
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'',
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0,
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'',
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0,
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0
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);
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if ($this->send_kex_first) {
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if (!$this->_send_binary_packet($kexinit_payload_client)) {
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return false;
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}
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$kexinit_payload_server = $this->_get_binary_packet();
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if ($kexinit_payload_server === false) {
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user_error('Connection closed by server');
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return false;
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}
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if (!strlen($kexinit_payload_server) || ord($kexinit_payload_server[0]) != NET_SSH2_MSG_KEXINIT) {
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user_error('Expected SSH_MSG_KEXINIT');
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return false;
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}
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}
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$response = $kexinit_payload_server;
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$this->_string_shift($response, 1); // skip past the message number (it should be SSH_MSG_KEXINIT)
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$server_cookie = $this->_string_shift($response, 16);
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@ -1387,39 +1516,9 @@ class Net_SSH2
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extract(unpack('Cfirst_kex_packet_follows', $this->_string_shift($response, 1)));
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$first_kex_packet_follows = $first_kex_packet_follows != 0;
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// the sending of SSH2_MSG_KEXINIT could go in one of two places. this is the second place.
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$kexinit_payload_client = pack(
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'Ca*Na*Na*Na*Na*Na*Na*Na*Na*Na*Na*CN',
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NET_SSH2_MSG_KEXINIT,
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$client_cookie,
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strlen($str_kex_algorithms),
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$str_kex_algorithms,
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strlen($str_server_host_key_algorithms),
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$str_server_host_key_algorithms,
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strlen($encryption_algorithms_client_to_server),
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$encryption_algorithms_client_to_server,
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strlen($encryption_algorithms_server_to_client),
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$encryption_algorithms_server_to_client,
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strlen($mac_algorithms_client_to_server),
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$mac_algorithms_client_to_server,
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strlen($mac_algorithms_server_to_client),
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$mac_algorithms_server_to_client,
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strlen($compression_algorithms_client_to_server),
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$compression_algorithms_client_to_server,
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strlen($compression_algorithms_server_to_client),
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$compression_algorithms_server_to_client,
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0,
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'',
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0,
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'',
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0,
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0
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);
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if (!$this->_send_binary_packet($kexinit_payload_client)) {
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if (!$this->send_kex_first && !$this->_send_binary_packet($kexinit_payload_client)) {
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return false;
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}
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// here ends the second place.
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// we need to decide upon the symmetric encryption algorithms before we do the diffie-hellman key exchange
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// we don't initialize any crypto-objects, yet - we do that, later. for now, we need the lengths to make the
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