/src/ndpi/src/lib/protocols/ssh.c

Source (jump to first uncovered line)
/*
 * ssh.c
 *
 * Copyright (C) 2011-25 - ntop.org
 * Copyright (C) 2009-11 - ipoque GmbH
 *
 * This file is part of nDPI, an open source deep packet inspection
 * library based on the OpenDPI and PACE technology by ipoque GmbH
 *
 * nDPI is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * nDPI 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with nDPI.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "ndpi_protocol_ids.h"

#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_SSH

#include "ndpi_api.h"
#include "ndpi_private.h"
#include "ndpi_md5.h"

#include <string.h>

/*
  HASSH - https://github.com/salesforce/hassh

  https://github.com/salesforce/hassh/blob/master/python/hassh.py

  [server]
  skex = packet.ssh.kex_algorithms
  seastc = packet.ssh.encryption_algorithms_server_to_client
  smastc = packet.ssh.mac_algorithms_server_to_client
  scastc = packet.ssh.compression_algorithms_server_to_client
  hasshs_str = ';'.join([skex, seastc, smastc, scastc]) 

  [client]
  ckex = packet.ssh.kex_algorithms
  ceacts = packet.ssh.encryption_algorithms_client_to_server
  cmacts = packet.ssh.mac_algorithms_client_to_server
  ccacts = packet.ssh.compression_algorithms_client_to_server
  hassh_str = ';'.join([ckex, ceacts, cmacts, ccacts]) 

  NOTE
  THe ECDSA key fingerprint is SHA256 -> ssh.kex.h_sig (wireshark)
  is in the Message Code: Diffie-Hellman Key Exchange Reply (31) 
  that usually is packet 14
*/

// #define SSH_DEBUG 1

static void ndpi_search_ssh_tcp(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow);

typedef struct {
  const char *signature;
  u_int16_t major, minor, patch;
} ssh_pattern;

/* ************************************************************************ */

static void ssh_analyze_signature_version(struct ndpi_detection_module_struct *ndpi_struct,
                                          struct ndpi_flow_struct *flow,
            char *str_to_check,
            u_int8_t is_client_signature) {
  u_int i;
  u_int8_t obsolete_ssh_version = 0;  
  const ssh_pattern ssh_servers_strings[] =
    {
     { (const char*)"SSH-%*f-OpenSSH_%d.%d.%d", 7, 0, 0 },     /* OpenSSH */
     { (const char*)"SSH-%*f-APACHE-SSHD-%d.%d.%d", 2, 5, 1 }, /* Apache MINA SSHD */
     { (const char*)"SSH-%*f-FileZilla_%d.%d.%d", 3, 40, 0 },  /* FileZilla SSH*/
     { (const char*)"SSH-%*f-paramiko_%d.%d.%d", 2, 4, 0 },    /* Paramiko SSH */
     { (const char*)"SSH-%*f-dropbear_%d.%d", 2020, 0, 0 },    /* Dropbear SSH */
     { NULL, 0, 0, 0 } 
    };

  for(i = 0; ssh_servers_strings[i].signature != NULL; i++) {
    int matches;
    int major   = 0;
    int minor   = 0;
    int patch   = 0;
    matches = sscanf(str_to_check, ssh_servers_strings[i].signature, &major, &minor, &patch);

    if(matches == 3 || matches == 2) {
      /* checking if is an old version */ 
      if(major < ssh_servers_strings[i].major)
  obsolete_ssh_version = 1;      
      else if(major == ssh_servers_strings[i].major) {   
  if(minor < ssh_servers_strings[i].minor)
    obsolete_ssh_version = 1; 
  else if(minor == ssh_servers_strings[i].minor)
    if(patch < ssh_servers_strings[i].patch)
      obsolete_ssh_version = 1;
      }

#ifdef SSH_DEBUG
      printf("[SSH] [SSH Version: %d.%d.%d]\n", major, minor, patch);
#endif
     
      break;
    }
  }
  
  if(obsolete_ssh_version)
    ndpi_set_risk(ndpi_struct, flow,
                  (is_client_signature ? NDPI_SSH_OBSOLETE_CLIENT_VERSION_OR_CIPHER : NDPI_SSH_OBSOLETE_SERVER_VERSION_OR_CIPHER),
                  NULL);
}
  
/* ************************************************************************ */

static void ssh_analyse_cipher(struct ndpi_detection_module_struct *ndpi_struct,
                               struct ndpi_flow_struct *flow,
             char *ciphers, u_int cipher_len,
             u_int8_t is_client_signature) {

  char *rem;
  char *cipher;
  u_int found_obsolete_cipher = 0;
  char *cipher_copy;
  /*
    List of obsolete ciphers can be found at
    https://www.linuxminion.com/deprecated-ssh-cryptographic-settings/
  */
  const char *obsolete_ciphers[] = {
            "arcfour256",
            "arcfour128",
            "3des-cbc",
            "blowfish-cbc",
            "cast128-cbc",
            "arcfour",
            NULL, 
  };

  if((cipher_copy = (char*)ndpi_malloc(cipher_len+1)) == NULL) {
#ifdef SSH_DEBUG
    printf("[SSH] Nout enough memory\n");
#endif
    return;
  }

  strncpy(cipher_copy, ciphers, cipher_len);
  cipher_copy[cipher_len] = '\0';

  cipher = strtok_r(cipher_copy, ",", &rem);

  while(cipher && !found_obsolete_cipher) {
    u_int i;
    
    for(i = 0; obsolete_ciphers[i]; i++) {
      if(strcmp(cipher, obsolete_ciphers[i]) == 0) {
        found_obsolete_cipher = i;
#ifdef SSH_DEBUG
  printf("[SSH] [SSH obsolete %s cipher][%s]\n",
         is_client_signature ? "client" : "server",
         obsolete_ciphers[i]);
#endif   
        break;
      }
    }

    cipher = strtok_r(NULL, ",", &rem);
  }

  if(found_obsolete_cipher) {
    char str[64];

    snprintf(str, sizeof(str), "Found cipher %s", obsolete_ciphers[found_obsolete_cipher]);
    ndpi_set_risk(ndpi_struct, flow,
      (is_client_signature ? NDPI_SSH_OBSOLETE_CLIENT_VERSION_OR_CIPHER : NDPI_SSH_OBSOLETE_SERVER_VERSION_OR_CIPHER),
      str);
  }

  ndpi_free(cipher_copy);
}

/* ************************************************************************ */

static int search_ssh_again(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow) {
  ndpi_search_ssh_tcp(ndpi_struct, flow);

  if((flow->protos.ssh.hassh_client[0] != '\0')
     && (flow->protos.ssh.hassh_server[0] != '\0')) {
    /* stop extra processing */
    flow->extra_packets_func = NULL; /* We're good now */
    return(0);
  }

  /* Possibly more processing */
  return(1);
}

/* ************************************************************************ */

static void ndpi_int_ssh_add_connection(struct ndpi_detection_module_struct
          *ndpi_struct, struct ndpi_flow_struct *flow) {
  if(flow->extra_packets_func != NULL)
    return;

  flow->max_extra_packets_to_check = 12;
  flow->extra_packets_func = search_ssh_again;
  
  ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SSH, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
}

/* ************************************************************************ */

static u_int16_t concat_hash_string(struct ndpi_detection_module_struct *ndpi_struct,
                                    struct ndpi_flow_struct *flow,
            struct ndpi_packet_struct *packet,
            char *buf, u_int8_t client_hash) {
  u_int32_t offset = 22, len, buf_out_len = 0, max_payload_len = packet->payload_packet_len-sizeof(u_int32_t);
  const u_int32_t len_max = 65565;
    
  if(offset >= max_payload_len)
    goto invalid_payload;

  len = ntohl(*(u_int32_t*)&packet->payload[offset]);
  offset += 4;

  /* -1 for ';' */
  if((offset >= packet->payload_packet_len) || (len >= packet->payload_packet_len-offset-1))
    goto invalid_payload;

  /* ssh.kex_algorithms [C/S] */
  strncpy(buf, (const char *)&packet->payload[offset], buf_out_len = len);
  buf[buf_out_len++] = ';';
  offset += len;

  if(offset >= max_payload_len)
    goto invalid_payload;
  
  /* ssh.server_host_key_algorithms [None] */
  len = ntohl(*(u_int32_t*)&packet->payload[offset]);

  if(len > len_max)
    goto invalid_payload;
  offset += 4 + len;

  if(offset >= max_payload_len)
    goto invalid_payload;

  /* ssh.encryption_algorithms_client_to_server [C] */
  len = ntohl(*(u_int32_t*)&packet->payload[offset]);

  offset += 4;
  if(client_hash) {
    if((offset >= packet->payload_packet_len) || (len >= packet->payload_packet_len-offset-1))
      goto invalid_payload;

    strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
    ssh_analyse_cipher(ndpi_struct, flow, (char*)&packet->payload[offset], len, 1 /* client */);
    buf_out_len += len;
    buf[buf_out_len++] = ';';
  }

  if(len > len_max)
    goto invalid_payload;
  offset += len;

  if(offset >= max_payload_len)
    goto invalid_payload;

  /* ssh.encryption_algorithms_server_to_client [S] */
  len = ntohl(*(u_int32_t*)&packet->payload[offset]);

  offset += 4;
  if(!client_hash) {
    if((offset >= packet->payload_packet_len) || (len >= packet->payload_packet_len-offset-1))
      goto invalid_payload;

    strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
    ssh_analyse_cipher(ndpi_struct, flow, (char*)&packet->payload[offset], len, 0 /* server */);
    buf_out_len += len;
    buf[buf_out_len++] = ';';
  }

  if(len > len_max)
    goto invalid_payload;
  offset += len;

  if(offset >= max_payload_len)
    goto invalid_payload;
  /* ssh.mac_algorithms_client_to_server [C] */
  len = ntohl(*(u_int32_t*)&packet->payload[offset]);

  offset += 4;
  if(client_hash) {
    if((offset >= packet->payload_packet_len) || (len >= packet->payload_packet_len-offset-1))
      goto invalid_payload;

    strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
    buf_out_len += len;
    buf[buf_out_len++] = ';';
  }
  
  if(len > len_max)
    goto invalid_payload;
  offset += len;

  if(offset >= max_payload_len)
    goto invalid_payload;
  /* ssh.mac_algorithms_server_to_client [S] */
  len = ntohl(*(u_int32_t*)&packet->payload[offset]);

  offset += 4;
  if(!client_hash) {
    if((offset >= packet->payload_packet_len) || (len >= packet->payload_packet_len-offset-1))
      goto invalid_payload;

    strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
    buf_out_len += len;
    buf[buf_out_len++] = ';';
  }

  if(len > len_max)
    goto invalid_payload;
  offset += len;

  /* ssh.compression_algorithms_client_to_server [C] */
  if(offset >= max_payload_len)
    goto invalid_payload;
  
  len = ntohl(*(u_int32_t*)&packet->payload[offset]);

  offset += 4;
  if(client_hash) {
    if((offset >= packet->payload_packet_len) || (len >= packet->payload_packet_len-offset-1))
      goto invalid_payload;

    strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
    buf_out_len += len;
  }

  if(len > len_max)
    goto invalid_payload;
  offset += len;

  if(offset >= max_payload_len)
    goto invalid_payload;
  /* ssh.compression_algorithms_server_to_client [S] */
  len = ntohl(*(u_int32_t*)&packet->payload[offset]);

  offset += 4;
  if(!client_hash) {
    if((offset >= packet->payload_packet_len) || (len >= packet->payload_packet_len-offset-1))
      goto invalid_payload;

    strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
    buf_out_len += len;
  }

  if(len > len_max)
    goto invalid_payload;

  /* ssh.languages_client_to_server [None] */

  /* ssh.languages_server_to_client [None] */

#ifdef SSH_DEBUG
  printf("[SSH] %s\n", buf);
#endif

  return(buf_out_len);

 invalid_payload:
#ifdef SSH_DEBUG
  printf("[SSH] Invalid packet payload\n");
#endif

  return(0);
}

/* ************************************************************************ */

static void ndpi_ssh_zap_cr(char *str, int len) {
  len--;

  while(len > 0) {
    if((str[len] == '\n') || (str[len] == '\r')) {
      str[len] = '\0';
      len--;
    } else
      break;
  }
}

/* ************************************************************************ */

static void ndpi_search_ssh_tcp(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow) {
  struct ndpi_packet_struct *packet = &ndpi_struct->packet;

#ifdef SSH_DEBUG
  printf("[SSH] %s()\n", __FUNCTION__);
#endif

  if(flow->l4.tcp.ssh_stage <= 1) {
    if(packet->payload_packet_len > 7 && memcmp(packet->payload, "SSH-", 4) == 0) {
      if(current_pkt_from_client_to_server(ndpi_struct, flow)) {
  int len = ndpi_min(sizeof(flow->protos.ssh.client_signature)-1, packet->payload_packet_len);
      
  strncpy(flow->protos.ssh.client_signature, (const char *)packet->payload, len);
  flow->protos.ssh.client_signature[len] = '\0';
  ndpi_ssh_zap_cr(flow->protos.ssh.client_signature, len);

  ssh_analyze_signature_version(ndpi_struct, flow, flow->protos.ssh.client_signature, 1);
      
#ifdef SSH_DEBUG
  printf("[SSH] [client_signature: %s]\n", flow->protos.ssh.client_signature);
#endif      
      
  ndpi_int_ssh_add_connection(ndpi_struct, flow);
      } else {
  int len = ndpi_min(sizeof(flow->protos.ssh.server_signature)-1, packet->payload_packet_len);
      
  strncpy(flow->protos.ssh.server_signature, (const char *)packet->payload, len);
  flow->protos.ssh.server_signature[len] = '\0';
  ndpi_ssh_zap_cr(flow->protos.ssh.server_signature, len);

  ssh_analyze_signature_version(ndpi_struct, flow, flow->protos.ssh.server_signature, 0);
      
#ifdef SSH_DEBUG
  printf("[SSH] [server_signature: %s]\n", flow->protos.ssh.server_signature);
#endif
      
  NDPI_LOG_DBG2(ndpi_struct, "ssh stage 1 passed\n");
  flow->fast_callback_protocol_id = NDPI_PROTOCOL_SSH;
      
#ifdef SSH_DEBUG
  printf("[SSH] [completed stage: %u]\n", flow->l4.tcp.ssh_stage);
#endif
      }

      flow->l4.tcp.ssh_stage++;
      return; 
    }
  } else if(packet->payload_packet_len > 5) {
    u_int8_t msgcode = *(packet->payload + 5);
    ndpi_MD5_CTX ctx;
    
    if(msgcode == 20 /* key exchange init */) {
      char *hassh_buf = ndpi_calloc(packet->payload_packet_len, sizeof(char));
      u_int i, len;

#ifdef SSH_DEBUG
      printf("[SSH] [stage: %u][msg: %u][direction: %u][key exchange init]\n", flow->l4.tcp.ssh_stage, msgcode, packet->packet_direction);
#endif

      if(hassh_buf) {
  if(packet->packet_direction == 0 /* client */) {
    u_char fingerprint_client[16];

    len = concat_hash_string(ndpi_struct, flow, packet, hassh_buf, 1 /* client */);

    ndpi_MD5Init(&ctx);
    ndpi_MD5Update(&ctx, (const unsigned char *)hassh_buf, len);
    ndpi_MD5Final(fingerprint_client, &ctx);

#ifdef SSH_DEBUG
    {
      printf("[SSH] [client][%s][", hassh_buf);
      for(i=0; i<16; i++) printf("%02X", fingerprint_client[i]);
      printf("]\n");
    }
#endif
    for(i=0; i<16; i++)
      snprintf(&flow->protos.ssh.hassh_client[i*2],
         sizeof(flow->protos.ssh.hassh_client) - (i*2),
         "%02X", fingerprint_client[i] & 0xFF);
    
    flow->protos.ssh.hassh_client[32] = '\0';
  } else {
    u_char fingerprint_server[16];

    len = concat_hash_string(ndpi_struct, flow, packet, hassh_buf, 0 /* server */);

    ndpi_MD5Init(&ctx);
    ndpi_MD5Update(&ctx, (const unsigned char *)hassh_buf, len);
    ndpi_MD5Final(fingerprint_server, &ctx);

#ifdef SSH_DEBUG
    {
      printf("[SSH] [server][%s][", hassh_buf);
      for(i=0; i<16; i++) printf("%02X", fingerprint_server[i]);
      printf("]\n");
    }
#endif

    for(i=0; i<16; i++)
      snprintf(&flow->protos.ssh.hassh_server[i*2],
         sizeof(flow->protos.ssh.hassh_server) - (i*2),
         "%02X", fingerprint_server[i] & 0xFF);
    flow->protos.ssh.hassh_server[32] = '\0';
  }

  ndpi_free(hassh_buf);
      }

      ndpi_int_ssh_add_connection(ndpi_struct, flow);
    }

    if((flow->protos.ssh.hassh_client[0] != '\0') && (flow->protos.ssh.hassh_server[0] != '\0')) {
#ifdef SSH_DEBUG
      printf("[SSH] Dissection completed\n");
#endif
      flow->extra_packets_func = NULL; /* We're good now */
    }

    return;
  }

#ifdef SSH_DEBUG
  printf("[SSH] Excluding SSH");
#endif

  NDPI_LOG_DBG(ndpi_struct, "excluding ssh at stage %d\n", flow->l4.tcp.ssh_stage);
  NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);
}

/* ************************************************************************ */

void init_ssh_dissector(struct ndpi_detection_module_struct *ndpi_struct)
{
  register_dissector("SSH", ndpi_struct,
                     ndpi_search_ssh_tcp,
                     NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
                     1, NDPI_PROTOCOL_SSH);
}

Coverage Report

Created: 2025-07-18 07:07

Line	Count	Source (jump to first uncovered line)
1		/*
2		* ssh.c
3		*
4		* Copyright (C) 2011-25 - ntop.org
5		* Copyright (C) 2009-11 - ipoque GmbH
6		*
7		* This file is part of nDPI, an open source deep packet inspection
8		* library based on the OpenDPI and PACE technology by ipoque GmbH
9		*
10		* nDPI is free software: you can redistribute it and/or modify
11		* it under the terms of the GNU Lesser General Public License as published by
12		* the Free Software Foundation, either version 3 of the License, or
13		* (at your option) any later version.
14		*
15		* nDPI is distributed in the hope that it will be useful,
16		* but WITHOUT ANY WARRANTY; without even the implied warranty of
17		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18		* GNU Lesser General Public License for more details.
19		*
20		* You should have received a copy of the GNU Lesser General Public License
21		* along with nDPI. If not, see <http://www.gnu.org/licenses/>.
22		*
23		*/
24
25		#include "ndpi_protocol_ids.h"
26
27		#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_SSH
28
29		#include "ndpi_api.h"
30		#include "ndpi_private.h"
31		#include "ndpi_md5.h"
32
33		#include <string.h>
34
35		/*
36		HASSH - https://github.com/salesforce/hassh
37
38		https://github.com/salesforce/hassh/blob/master/python/hassh.py
39
40		[server]
41		skex = packet.ssh.kex_algorithms
42		seastc = packet.ssh.encryption_algorithms_server_to_client
43		smastc = packet.ssh.mac_algorithms_server_to_client
44		scastc = packet.ssh.compression_algorithms_server_to_client
45		hasshs_str = ';'.join([skex, seastc, smastc, scastc])
46
47		[client]
48		ckex = packet.ssh.kex_algorithms
49		ceacts = packet.ssh.encryption_algorithms_client_to_server
50		cmacts = packet.ssh.mac_algorithms_client_to_server
51		ccacts = packet.ssh.compression_algorithms_client_to_server
52		hassh_str = ';'.join([ckex, ceacts, cmacts, ccacts])
53
54		NOTE
55		THe ECDSA key fingerprint is SHA256 -> ssh.kex.h_sig (wireshark)
56		is in the Message Code: Diffie-Hellman Key Exchange Reply (31)
57		that usually is packet 14
58		*/
59
60		// #define SSH_DEBUG 1
61
62		static void ndpi_search_ssh_tcp(struct ndpi_detection_module_struct ndpi_struct, struct ndpi_flow_struct flow);
63
64		typedef struct {
65		const char *signature;
66		u_int16_t major, minor, patch;
67		} ssh_pattern;
68
69		/* ************************************************************************ */
70
71		static void ssh_analyze_signature_version(struct ndpi_detection_module_struct *ndpi_struct,
72		struct ndpi_flow_struct *flow,
73		char *str_to_check,
74	0	u_int8_t is_client_signature) {
75	0	u_int i;
76	0	u_int8_t obsolete_ssh_version = 0;
77	0	const ssh_pattern ssh_servers_strings[] =
78	0	{
79	0	{ (const char)"SSH-%f-OpenSSH_%d.%d.%d", 7, 0, 0 }, /* OpenSSH */
80	0	{ (const char)"SSH-%f-APACHE-SSHD-%d.%d.%d", 2, 5, 1 }, /* Apache MINA SSHD */
81	0	{ (const char)"SSH-%f-FileZilla_%d.%d.%d", 3, 40, 0 }, /* FileZilla SSH*/
82	0	{ (const char)"SSH-%f-paramiko_%d.%d.%d", 2, 4, 0 }, /* Paramiko SSH */
83	0	{ (const char)"SSH-%f-dropbear_%d.%d", 2020, 0, 0 }, /* Dropbear SSH */
84	0	{ NULL, 0, 0, 0 }
85	0	};
86
87	0	for(i = 0; ssh_servers_strings[i].signature != NULL; i++) {
88	0	int matches;
89	0	int major = 0;
90	0	int minor = 0;
91	0	int patch = 0;
92	0	matches = sscanf(str_to_check, ssh_servers_strings[i].signature, &major, &minor, &patch);
93
94	0	if(matches == 3 \|\| matches == 2) {
95		/* checking if is an old version */
96	0	if(major < ssh_servers_strings[i].major)
97	0	obsolete_ssh_version = 1;
98	0	else if(major == ssh_servers_strings[i].major) {
99	0	if(minor < ssh_servers_strings[i].minor)
100	0	obsolete_ssh_version = 1;
101	0	else if(minor == ssh_servers_strings[i].minor)
102	0	if(patch < ssh_servers_strings[i].patch)
103	0	obsolete_ssh_version = 1;
104	0	}
105
106		#ifdef SSH_DEBUG
107		printf("[SSH] [SSH Version: %d.%d.%d]\n", major, minor, patch);
108		#endif
109
110	0	break;
111	0	}
112	0	}
113
114	0	if(obsolete_ssh_version)
115	0	ndpi_set_risk(ndpi_struct, flow,
116	0	(is_client_signature ? NDPI_SSH_OBSOLETE_CLIENT_VERSION_OR_CIPHER : NDPI_SSH_OBSOLETE_SERVER_VERSION_OR_CIPHER),
117	0	NULL);
118	0	}
119
120		/* ************************************************************************ */
121
122		static void ssh_analyse_cipher(struct ndpi_detection_module_struct *ndpi_struct,
123		struct ndpi_flow_struct *flow,
124		char *ciphers, u_int cipher_len,
125	0	u_int8_t is_client_signature) {
126
127	0	char *rem;
128	0	char *cipher;
129	0	u_int found_obsolete_cipher = 0;
130	0	char *cipher_copy;
131		/*
132		List of obsolete ciphers can be found at
133		https://www.linuxminion.com/deprecated-ssh-cryptographic-settings/
134		*/
135	0	const char *obsolete_ciphers[] = {
136	0	"arcfour256",
137	0	"arcfour128",
138	0	"3des-cbc",
139	0	"blowfish-cbc",
140	0	"cast128-cbc",
141	0	"arcfour",
142	0	NULL,
143	0	};
144
145	0	if((cipher_copy = (char*)ndpi_malloc(cipher_len+1)) == NULL) {
146		#ifdef SSH_DEBUG
147		printf("[SSH] Nout enough memory\n");
148		#endif
149	0	return;
150	0	}
151
152	0	strncpy(cipher_copy, ciphers, cipher_len);
153	0	cipher_copy[cipher_len] = '\0';
154
155	0	cipher = strtok_r(cipher_copy, ",", &rem);
156
157	0	while(cipher && !found_obsolete_cipher) {
158	0	u_int i;
159
160	0	for(i = 0; obsolete_ciphers[i]; i++) {
161	0	if(strcmp(cipher, obsolete_ciphers[i]) == 0) {
162	0	found_obsolete_cipher = i;
163		#ifdef SSH_DEBUG
164		printf("[SSH] [SSH obsolete %s cipher][%s]\n",
165		is_client_signature ? "client" : "server",
166		obsolete_ciphers[i]);
167		#endif
168	0	break;
169	0	}
170	0	}
171
172	0	cipher = strtok_r(NULL, ",", &rem);
173	0	}
174
175	0	if(found_obsolete_cipher) {
176	0	char str[64];
177
178	0	snprintf(str, sizeof(str), "Found cipher %s", obsolete_ciphers[found_obsolete_cipher]);
179	0	ndpi_set_risk(ndpi_struct, flow,
180	0	(is_client_signature ? NDPI_SSH_OBSOLETE_CLIENT_VERSION_OR_CIPHER : NDPI_SSH_OBSOLETE_SERVER_VERSION_OR_CIPHER),
181	0	str);
182	0	}
183
184	0	ndpi_free(cipher_copy);
185	0	}
186
187		/* ************************************************************************ */
188
189	0	static int search_ssh_again(struct ndpi_detection_module_struct ndpi_struct, struct ndpi_flow_struct flow) {
190	0	ndpi_search_ssh_tcp(ndpi_struct, flow);
191
192	0	if((flow->protos.ssh.hassh_client[0] != '\0')
193	0	&& (flow->protos.ssh.hassh_server[0] != '\0')) {
194		/* stop extra processing */
195	0	flow->extra_packets_func = NULL; /* We're good now */
196	0	return(0);
197	0	}
198
199		/* Possibly more processing */
200	0	return(1);
201	0	}
202
203		/* ************************************************************************ */
204
205		static void ndpi_int_ssh_add_connection(struct ndpi_detection_module_struct
206	0	ndpi_struct, struct ndpi_flow_struct flow) {
207	0	if(flow->extra_packets_func != NULL)
208	0	return;
209
210	0	flow->max_extra_packets_to_check = 12;
211	0	flow->extra_packets_func = search_ssh_again;
212
213	0	ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SSH, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
214	0	}
215
216		/* ************************************************************************ */
217
218		static u_int16_t concat_hash_string(struct ndpi_detection_module_struct *ndpi_struct,
219		struct ndpi_flow_struct *flow,
220		struct ndpi_packet_struct *packet,
221	0	char *buf, u_int8_t client_hash) {
222	0	u_int32_t offset = 22, len, buf_out_len = 0, max_payload_len = packet->payload_packet_len-sizeof(u_int32_t);
223	0	const u_int32_t len_max = 65565;
224
225	0	if(offset >= max_payload_len)
226	0	goto invalid_payload;
227
228	0	len = ntohl((u_int32_t)&packet->payload[offset]);
229	0	offset += 4;
230
231		/* -1 for ';' */
232	0	if((offset >= packet->payload_packet_len) \|\| (len >= packet->payload_packet_len-offset-1))
233	0	goto invalid_payload;
234
235		/* ssh.kex_algorithms [C/S] */
236	0	strncpy(buf, (const char *)&packet->payload[offset], buf_out_len = len);
237	0	buf[buf_out_len++] = ';';
238	0	offset += len;
239
240	0	if(offset >= max_payload_len)
241	0	goto invalid_payload;
242
243		/* ssh.server_host_key_algorithms [None] */
244	0	len = ntohl((u_int32_t)&packet->payload[offset]);
245
246	0	if(len > len_max)
247	0	goto invalid_payload;
248	0	offset += 4 + len;
249
250	0	if(offset >= max_payload_len)
251	0	goto invalid_payload;
252
253		/* ssh.encryption_algorithms_client_to_server [C] */
254	0	len = ntohl((u_int32_t)&packet->payload[offset]);
255
256	0	offset += 4;
257	0	if(client_hash) {
258	0	if((offset >= packet->payload_packet_len) \|\| (len >= packet->payload_packet_len-offset-1))
259	0	goto invalid_payload;
260
261	0	strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
262	0	ssh_analyse_cipher(ndpi_struct, flow, (char)&packet->payload[offset], len, 1 / client */);
263	0	buf_out_len += len;
264	0	buf[buf_out_len++] = ';';
265	0	}
266
267	0	if(len > len_max)
268	0	goto invalid_payload;
269	0	offset += len;
270
271	0	if(offset >= max_payload_len)
272	0	goto invalid_payload;
273
274		/* ssh.encryption_algorithms_server_to_client [S] */
275	0	len = ntohl((u_int32_t)&packet->payload[offset]);
276
277	0	offset += 4;
278	0	if(!client_hash) {
279	0	if((offset >= packet->payload_packet_len) \|\| (len >= packet->payload_packet_len-offset-1))
280	0	goto invalid_payload;
281
282	0	strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
283	0	ssh_analyse_cipher(ndpi_struct, flow, (char)&packet->payload[offset], len, 0 / server */);
284	0	buf_out_len += len;
285	0	buf[buf_out_len++] = ';';
286	0	}
287
288	0	if(len > len_max)
289	0	goto invalid_payload;
290	0	offset += len;
291
292	0	if(offset >= max_payload_len)
293	0	goto invalid_payload;
294		/* ssh.mac_algorithms_client_to_server [C] */
295	0	len = ntohl((u_int32_t)&packet->payload[offset]);
296
297	0	offset += 4;
298	0	if(client_hash) {
299	0	if((offset >= packet->payload_packet_len) \|\| (len >= packet->payload_packet_len-offset-1))
300	0	goto invalid_payload;
301
302	0	strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
303	0	buf_out_len += len;
304	0	buf[buf_out_len++] = ';';
305	0	}
306
307	0	if(len > len_max)
308	0	goto invalid_payload;
309	0	offset += len;
310
311	0	if(offset >= max_payload_len)
312	0	goto invalid_payload;
313		/* ssh.mac_algorithms_server_to_client [S] */
314	0	len = ntohl((u_int32_t)&packet->payload[offset]);
315
316	0	offset += 4;
317	0	if(!client_hash) {
318	0	if((offset >= packet->payload_packet_len) \|\| (len >= packet->payload_packet_len-offset-1))
319	0	goto invalid_payload;
320
321	0	strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
322	0	buf_out_len += len;
323	0	buf[buf_out_len++] = ';';
324	0	}
325
326	0	if(len > len_max)
327	0	goto invalid_payload;
328	0	offset += len;
329
330		/* ssh.compression_algorithms_client_to_server [C] */
331	0	if(offset >= max_payload_len)
332	0	goto invalid_payload;
333
334	0	len = ntohl((u_int32_t)&packet->payload[offset]);
335
336	0	offset += 4;
337	0	if(client_hash) {
338	0	if((offset >= packet->payload_packet_len) \|\| (len >= packet->payload_packet_len-offset-1))
339	0	goto invalid_payload;
340
341	0	strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
342	0	buf_out_len += len;
343	0	}
344
345	0	if(len > len_max)
346	0	goto invalid_payload;
347	0	offset += len;
348
349	0	if(offset >= max_payload_len)
350	0	goto invalid_payload;
351		/* ssh.compression_algorithms_server_to_client [S] */
352	0	len = ntohl((u_int32_t)&packet->payload[offset]);
353
354	0	offset += 4;
355	0	if(!client_hash) {
356	0	if((offset >= packet->payload_packet_len) \|\| (len >= packet->payload_packet_len-offset-1))
357	0	goto invalid_payload;
358
359	0	strncpy(&buf[buf_out_len], (const char *)&packet->payload[offset], len);
360	0	buf_out_len += len;
361	0	}
362
363	0	if(len > len_max)
364	0	goto invalid_payload;
365
366		/* ssh.languages_client_to_server [None] */
367
368		/* ssh.languages_server_to_client [None] */
369
370		#ifdef SSH_DEBUG
371		printf("[SSH] %s\n", buf);
372		#endif
373
374	0	return(buf_out_len);
375
376	0	invalid_payload:
377		#ifdef SSH_DEBUG
378		printf("[SSH] Invalid packet payload\n");
379		#endif
380
381	0	return(0);
382	0	}
383
384		/* ************************************************************************ */
385
386	0	static void ndpi_ssh_zap_cr(char *str, int len) {
387	0	len--;
388
389	0	while(len > 0) {
390	0	if((str[len] == '\n') \|\| (str[len] == '\r')) {
391	0	str[len] = '\0';
392	0	len--;
393	0	} else
394	0	break;
395	0	}
396	0	}
397
398		/* ************************************************************************ */
399
400	1.99k	static void ndpi_search_ssh_tcp(struct ndpi_detection_module_struct ndpi_struct, struct ndpi_flow_struct flow) {
401	1.99k	struct ndpi_packet_struct *packet = &ndpi_struct->packet;
402
403		#ifdef SSH_DEBUG
404		printf("[SSH] %s()\n", __FUNCTION__);
405		#endif
406
407	1.99k	if(flow->l4.tcp.ssh_stage <= 1) {
408	1.99k	if(packet->payload_packet_len > 7 && memcmp(packet->payload, "SSH-", 4) == 0) {
409	0	if(current_pkt_from_client_to_server(ndpi_struct, flow)) {
410	0	int len = ndpi_min(sizeof(flow->protos.ssh.client_signature)-1, packet->payload_packet_len);
411
412	0	strncpy(flow->protos.ssh.client_signature, (const char *)packet->payload, len);
413	0	flow->protos.ssh.client_signature[len] = '\0';
414	0	ndpi_ssh_zap_cr(flow->protos.ssh.client_signature, len);
415
416	0	ssh_analyze_signature_version(ndpi_struct, flow, flow->protos.ssh.client_signature, 1);
417
418		#ifdef SSH_DEBUG
419		printf("[SSH] [client_signature: %s]\n", flow->protos.ssh.client_signature);
420		#endif
421
422	0	ndpi_int_ssh_add_connection(ndpi_struct, flow);
423	0	} else {
424	0	int len = ndpi_min(sizeof(flow->protos.ssh.server_signature)-1, packet->payload_packet_len);
425
426	0	strncpy(flow->protos.ssh.server_signature, (const char *)packet->payload, len);
427	0	flow->protos.ssh.server_signature[len] = '\0';
428	0	ndpi_ssh_zap_cr(flow->protos.ssh.server_signature, len);
429
430	0	ssh_analyze_signature_version(ndpi_struct, flow, flow->protos.ssh.server_signature, 0);
431
432		#ifdef SSH_DEBUG
433		printf("[SSH] [server_signature: %s]\n", flow->protos.ssh.server_signature);
434		#endif
435
436	0	NDPI_LOG_DBG2(ndpi_struct, "ssh stage 1 passed\n");
437	0	flow->fast_callback_protocol_id = NDPI_PROTOCOL_SSH;
438
439		#ifdef SSH_DEBUG
440		printf("[SSH] [completed stage: %u]\n", flow->l4.tcp.ssh_stage);
441		#endif
442	0	}
443
444	0	flow->l4.tcp.ssh_stage++;
445	0	return;
446	0	}
447	1.99k	} else if(packet->payload_packet_len > 5) {
448	0	u_int8_t msgcode = *(packet->payload + 5);
449	0	ndpi_MD5_CTX ctx;
450
451	0	if(msgcode == 20 /* key exchange init */) {
452	0	char *hassh_buf = ndpi_calloc(packet->payload_packet_len, sizeof(char));
453	0	u_int i, len;
454
455		#ifdef SSH_DEBUG
456		printf("[SSH] [stage: %u][msg: %u][direction: %u][key exchange init]\n", flow->l4.tcp.ssh_stage, msgcode, packet->packet_direction);
457		#endif
458
459	0	if(hassh_buf) {
460	0	if(packet->packet_direction == 0 /* client */) {
461	0	u_char fingerprint_client[16];
462
463	0	len = concat_hash_string(ndpi_struct, flow, packet, hassh_buf, 1 /* client */);
464
465	0	ndpi_MD5Init(&ctx);
466	0	ndpi_MD5Update(&ctx, (const unsigned char *)hassh_buf, len);
467	0	ndpi_MD5Final(fingerprint_client, &ctx);
468
469		#ifdef SSH_DEBUG
470		{
471		printf("[SSH] [client][%s][", hassh_buf);
472		for(i=0; i<16; i++) printf("%02X", fingerprint_client[i]);
473		printf("]\n");
474		}
475		#endif
476	0	for(i=0; i<16; i++)
477	0	snprintf(&flow->protos.ssh.hassh_client[i*2],
478	0	sizeof(flow->protos.ssh.hassh_client) - (i*2),
479	0	"%02X", fingerprint_client[i] & 0xFF);
480
481	0	flow->protos.ssh.hassh_client[32] = '\0';
482	0	} else {
483	0	u_char fingerprint_server[16];
484
485	0	len = concat_hash_string(ndpi_struct, flow, packet, hassh_buf, 0 /* server */);
486
487	0	ndpi_MD5Init(&ctx);
488	0	ndpi_MD5Update(&ctx, (const unsigned char *)hassh_buf, len);
489	0	ndpi_MD5Final(fingerprint_server, &ctx);
490
491		#ifdef SSH_DEBUG
492		{
493		printf("[SSH] [server][%s][", hassh_buf);
494		for(i=0; i<16; i++) printf("%02X", fingerprint_server[i]);
495		printf("]\n");
496		}
497		#endif
498
499	0	for(i=0; i<16; i++)
500	0	snprintf(&flow->protos.ssh.hassh_server[i*2],
501	0	sizeof(flow->protos.ssh.hassh_server) - (i*2),
502	0	"%02X", fingerprint_server[i] & 0xFF);
503	0	flow->protos.ssh.hassh_server[32] = '\0';
504	0	}
505
506	0	ndpi_free(hassh_buf);
507	0	}
508
509	0	ndpi_int_ssh_add_connection(ndpi_struct, flow);
510	0	}
511
512	0	if((flow->protos.ssh.hassh_client[0] != '\0') && (flow->protos.ssh.hassh_server[0] != '\0')) {
513		#ifdef SSH_DEBUG
514		printf("[SSH] Dissection completed\n");
515		#endif
516	0	flow->extra_packets_func = NULL; /* We're good now */
517	0	}
518
519	0	return;
520	0	}
521
522		#ifdef SSH_DEBUG
523		printf("[SSH] Excluding SSH");
524		#endif
525
526	1.99k	NDPI_LOG_DBG(ndpi_struct, "excluding ssh at stage %d\n", flow->l4.tcp.ssh_stage);
527	1.99k	NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);
528	1.99k	}
529
530		/* ************************************************************************ */
531
532		void init_ssh_dissector(struct ndpi_detection_module_struct *ndpi_struct)
533	7.49k	{
534	7.49k	register_dissector("SSH", ndpi_struct,
535	7.49k	ndpi_search_ssh_tcp,
536	7.49k	NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
537	7.49k	1, NDPI_PROTOCOL_SSH);
538	7.49k	}