| sshd.0 (207311) | sshd.0 (214979) |
|---|---|
| 1SSHD(8) OpenBSD System Manager's Manual SSHD(8) 2 3NAME 4 sshd - OpenSSH SSH daemon 5 6SYNOPSIS 7 sshd [-46DdeiqTt] [-b bits] [-C connection_spec] 8 [-c host_certificate_file] [-f config_file] [-g login_grace_time] 9 [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len] 10 11DESCRIPTION 12 sshd (OpenSSH Daemon) is the daemon program for ssh(1). Together these | 1SSHD(8) OpenBSD System Manager's Manual SSHD(8) 2 3NAME 4 sshd - OpenSSH SSH daemon 5 6SYNOPSIS 7 sshd [-46DdeiqTt] [-b bits] [-C connection_spec] 8 [-c host_certificate_file] [-f config_file] [-g login_grace_time] 9 [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len] 10 11DESCRIPTION 12 sshd (OpenSSH Daemon) is the daemon program for ssh(1). Together these |
| 13 programs replace rlogin(1) and rsh(1), and provide secure encrypted com- 14 munications between two untrusted hosts over an insecure network. | 13 programs replace rlogin(1) and rsh(1), and provide secure encrypted 14 communications between two untrusted hosts over an insecure network. |
| 15 16 sshd listens for connections from clients. It is normally started at 17 boot from /etc/rc. It forks a new daemon for each incoming connection. | 15 16 sshd listens for connections from clients. It is normally started at 17 boot from /etc/rc. It forks a new daemon for each incoming connection. |
| 18 The forked daemons handle key exchange, encryption, authentication, com- 19 mand execution, and data exchange. | 18 The forked daemons handle key exchange, encryption, authentication, 19 command execution, and data exchange. |
| 20 21 sshd can be configured using command-line options or a configuration file | 20 21 sshd can be configured using command-line options or a configuration file |
| 22 (by default sshd_config(5)); command-line options override values speci- 23 fied in the configuration file. sshd rereads its configuration file when 24 it receives a hangup signal, SIGHUP, by executing itself with the name 25 and options it was started with, e.g. /usr/sbin/sshd. | 22 (by default sshd_config(5)); command-line options override values 23 specified in the configuration file. sshd rereads its configuration file 24 when it receives a hangup signal, SIGHUP, by executing itself with the 25 name and options it was started with, e.g. /usr/sbin/sshd. |
| 26 27 The options are as follows: 28 29 -4 Forces sshd to use IPv4 addresses only. 30 31 -6 Forces sshd to use IPv6 addresses only. 32 33 -b bits 34 Specifies the number of bits in the ephemeral protocol version 1 35 server key (default 1024). 36 37 -C connection_spec 38 Specify the connection parameters to use for the -T extended test 39 mode. If provided, any Match directives in the configuration 40 file that would apply to the specified user, host, and address | 26 27 The options are as follows: 28 29 -4 Forces sshd to use IPv4 addresses only. 30 31 -6 Forces sshd to use IPv6 addresses only. 32 33 -b bits 34 Specifies the number of bits in the ephemeral protocol version 1 35 server key (default 1024). 36 37 -C connection_spec 38 Specify the connection parameters to use for the -T extended test 39 mode. If provided, any Match directives in the configuration 40 file that would apply to the specified user, host, and address |
| 41 will be set before the configuration is written to standard out- 42 put. The connection parameters are supplied as keyword=value | 41 will be set before the configuration is written to standard 42 output. The connection parameters are supplied as keyword=value |
| 43 pairs. The keywords are ``user'', ``host'', and ``addr''. All | 43 pairs. The keywords are ``user'', ``host'', and ``addr''. All |
| 44 are required and may be supplied in any order, either with multi- 45 ple -C options or as a comma-separated list. | 44 are required and may be supplied in any order, either with 45 multiple -C options or as a comma-separated list. |
| 46 47 -c host_certificate_file 48 Specifies a path to a certificate file to identify sshd during 49 key exchange. The certificate file must match a host key file | 46 47 -c host_certificate_file 48 Specifies a path to a certificate file to identify sshd during 49 key exchange. The certificate file must match a host key file |
| 50 specified using the -h option or the HostKey configuration direc- 51 tive. | 50 specified using the -h option or the HostKey configuration 51 directive. |
| 52 53 -D When this option is specified, sshd will not detach and does not 54 become a daemon. This allows easy monitoring of sshd. 55 56 -d Debug mode. The server sends verbose debug output to standard | 52 53 -D When this option is specified, sshd will not detach and does not 54 become a daemon. This allows easy monitoring of sshd. 55 56 -d Debug mode. The server sends verbose debug output to standard |
| 57 error, and does not put itself in the background. The server al- 58 so will not fork and will only process one connection. This op- 59 tion is only intended for debugging for the server. Multiple -d 60 options increase the debugging level. Maximum is 3. | 57 error, and does not put itself in the background. The server 58 also will not fork and will only process one connection. This 59 option is only intended for debugging for the server. Multiple 60 -d options increase the debugging level. Maximum is 3. |
| 61 62 -e When this option is specified, sshd will send the output to the 63 standard error instead of the system log. 64 65 -f config_file 66 Specifies the name of the configuration file. The default is | 61 62 -e When this option is specified, sshd will send the output to the 63 standard error instead of the system log. 64 65 -f config_file 66 Specifies the name of the configuration file. The default is |
| 67 /etc/ssh/sshd_config. sshd refuses to start if there is no con- 68 figuration file. | 67 /etc/ssh/sshd_config. sshd refuses to start if there is no 68 configuration file. |
| 69 70 -g login_grace_time | 69 70 -g login_grace_time |
| 71 Gives the grace time for clients to authenticate themselves (de- 72 fault 120 seconds). If the client fails to authenticate the user 73 within this many seconds, the server disconnects and exits. A 74 value of zero indicates no limit. | 71 Gives the grace time for clients to authenticate themselves 72 (default 120 seconds). If the client fails to authenticate the 73 user within this many seconds, the server disconnects and exits. 74 A value of zero indicates no limit. |
| 75 76 -h host_key_file 77 Specifies a file from which a host key is read. This option must 78 be given if sshd is not run as root (as the normal host key files 79 are normally not readable by anyone but root). The default is 80 /etc/ssh/ssh_host_key for protocol version 1, and | 75 76 -h host_key_file 77 Specifies a file from which a host key is read. This option must 78 be given if sshd is not run as root (as the normal host key files 79 are normally not readable by anyone but root). The default is 80 /etc/ssh/ssh_host_key for protocol version 1, and |
| 81 /etc/ssh/ssh_host_rsa_key and /etc/ssh/ssh_host_dsa_key for pro- 82 tocol version 2. It is possible to have multiple host key files 83 for the different protocol versions and host key algorithms. | 81 /etc/ssh/ssh_host_rsa_key and /etc/ssh/ssh_host_dsa_key for 82 protocol version 2. It is possible to have multiple host key 83 files for the different protocol versions and host key 84 algorithms. |
| 84 85 -i Specifies that sshd is being run from inetd(8). sshd is normally 86 not run from inetd because it needs to generate the server key 87 before it can respond to the client, and this may take tens of | 85 86 -i Specifies that sshd is being run from inetd(8). sshd is normally 87 not run from inetd because it needs to generate the server key 88 before it can respond to the client, and this may take tens of |
| 88 seconds. Clients would have to wait too long if the key was re- 89 generated every time. However, with small key sizes (e.g. 512) | 89 seconds. Clients would have to wait too long if the key was 90 regenerated every time. However, with small key sizes (e.g. 512) |
| 90 using sshd from inetd may be feasible. 91 92 -k key_gen_time 93 Specifies how often the ephemeral protocol version 1 server key | 91 using sshd from inetd may be feasible. 92 93 -k key_gen_time 94 Specifies how often the ephemeral protocol version 1 server key |
| 94 is regenerated (default 3600 seconds, or one hour). The motiva- 95 tion for regenerating the key fairly often is that the key is not 96 stored anywhere, and after about an hour it becomes impossible to 97 recover the key for decrypting intercepted communications even if 98 the machine is cracked into or physically seized. A value of ze- 99 ro indicates that the key will never be regenerated. | 95 is regenerated (default 3600 seconds, or one hour). The 96 motivation for regenerating the key fairly often is that the key 97 is not stored anywhere, and after about an hour it becomes 98 impossible to recover the key for decrypting intercepted 99 communications even if the machine is cracked into or physically 100 seized. A value of zero indicates that the key will never be 101 regenerated. |
| 100 101 -o option | 102 103 -o option |
| 102 Can be used to give options in the format used in the configura- 103 tion file. This is useful for specifying options for which there 104 is no separate command-line flag. For full details of the op- 105 tions, and their values, see sshd_config(5). | 104 Can be used to give options in the format used in the 105 configuration file. This is useful for specifying options for 106 which there is no separate command-line flag. For full details 107 of the options, and their values, see sshd_config(5). |
| 106 107 -p port 108 Specifies the port on which the server listens for connections | 108 109 -p port 110 Specifies the port on which the server listens for connections |
| 109 (default 22). Multiple port options are permitted. Ports speci- 110 fied in the configuration file with the Port option are ignored 111 when a command-line port is specified. Ports specified using the 112 ListenAddress option override command-line ports. | 111 (default 22). Multiple port options are permitted. Ports 112 specified in the configuration file with the Port option are 113 ignored when a command-line port is specified. Ports specified 114 using the ListenAddress option override command-line ports. |
| 113 | 115 |
| 114 -q Quiet mode. Nothing is sent to the system log. Normally the be- 115 ginning, authentication, and termination of each connection is | 116 -q Quiet mode. Nothing is sent to the system log. Normally the 117 beginning, authentication, and termination of each connection is |
| 116 logged. 117 118 -T Extended test mode. Check the validity of the configuration 119 file, output the effective configuration to stdout and then exit. | 118 logged. 119 120 -T Extended test mode. Check the validity of the configuration 121 file, output the effective configuration to stdout and then exit. |
| 120 Optionally, Match rules may be applied by specifying the connec- 121 tion parameters using one or more -C options. | 122 Optionally, Match rules may be applied by specifying the 123 connection parameters using one or more -C options. |
| 122 123 -t Test mode. Only check the validity of the configuration file and 124 sanity of the keys. This is useful for updating sshd reliably as 125 configuration options may change. 126 127 -u len This option is used to specify the size of the field in the utmp 128 structure that holds the remote host name. If the resolved host 129 name is longer than len, the dotted decimal value will be used | 124 125 -t Test mode. Only check the validity of the configuration file and 126 sanity of the keys. This is useful for updating sshd reliably as 127 configuration options may change. 128 129 -u len This option is used to specify the size of the field in the utmp 130 structure that holds the remote host name. If the resolved host 131 name is longer than len, the dotted decimal value will be used |
| 130 instead. This allows hosts with very long host names that over- 131 flow this field to still be uniquely identified. Specifying -u0 132 indicates that only dotted decimal addresses should be put into 133 the utmp file. -u0 may also be used to prevent sshd from making 134 DNS requests unless the authentication mechanism or configuration 135 requires it. Authentication mechanisms that may require DNS in- 136 clude RhostsRSAAuthentication, HostbasedAuthentication, and using 137 a from="pattern-list" option in a key file. Configuration op- 138 tions that require DNS include using a USER@HOST pattern in 139 AllowUsers or DenyUsers. | 132 instead. This allows hosts with very long host names that 133 overflow this field to still be uniquely identified. Specifying 134 -u0 indicates that only dotted decimal addresses should be put 135 into the utmp file. -u0 may also be used to prevent sshd from 136 making DNS requests unless the authentication mechanism or 137 configuration requires it. Authentication mechanisms that may 138 require DNS include RhostsRSAAuthentication, 139 HostbasedAuthentication, and using a from="pattern-list" option 140 in a key file. Configuration options that require DNS include 141 using a USER@HOST pattern in AllowUsers or DenyUsers. |
| 140 141AUTHENTICATION 142 The OpenSSH SSH daemon supports SSH protocols 1 and 2. The default is to 143 use protocol 2 only, though this can be changed via the Protocol option 144 in sshd_config(5). Protocol 2 supports both RSA and DSA keys; protocol 1 | 142 143AUTHENTICATION 144 The OpenSSH SSH daemon supports SSH protocols 1 and 2. The default is to 145 use protocol 2 only, though this can be changed via the Protocol option 146 in sshd_config(5). Protocol 2 supports both RSA and DSA keys; protocol 1 |
| 145 only supports RSA keys. For both protocols, each host has a host-specif- 146 ic key, normally 2048 bits, used to identify the host. | 147 only supports RSA keys. For both protocols, each host has a host- 148 specific key, normally 2048 bits, used to identify the host. |
| 147 148 Forward security for protocol 1 is provided through an additional server 149 key, normally 768 bits, generated when the server starts. This key is 150 normally regenerated every hour if it has been used, and is never stored 151 on disk. Whenever a client connects, the daemon responds with its public 152 host and server keys. The client compares the RSA host key against its | 149 150 Forward security for protocol 1 is provided through an additional server 151 key, normally 768 bits, generated when the server starts. This key is 152 normally regenerated every hour if it has been used, and is never stored 153 on disk. Whenever a client connects, the daemon responds with its public 154 host and server keys. The client compares the RSA host key against its |
| 153 own database to verify that it has not changed. The client then gener- 154 ates a 256-bit random number. It encrypts this random number using both 155 the host key and the server key, and sends the encrypted number to the 156 server. Both sides then use this random number as a session key which is 157 used to encrypt all further communications in the session. The rest of 158 the session is encrypted using a conventional cipher, currently Blowfish 159 or 3DES, with 3DES being used by default. The client selects the encryp- 160 tion algorithm to use from those offered by the server. | 155 own database to verify that it has not changed. The client then 156 generates a 256-bit random number. It encrypts this random number using 157 both the host key and the server key, and sends the encrypted number to 158 the server. Both sides then use this random number as a session key 159 which is used to encrypt all further communications in the session. The 160 rest of the session is encrypted using a conventional cipher, currently 161 Blowfish or 3DES, with 3DES being used by default. The client selects 162 the encryption algorithm to use from those offered by the server. |
| 161 162 For protocol 2, forward security is provided through a Diffie-Hellman key 163 agreement. This key agreement results in a shared session key. The rest 164 of the session is encrypted using a symmetric cipher, currently 128-bit 165 AES, Blowfish, 3DES, CAST128, Arcfour, 192-bit AES, or 256-bit AES. The 166 client selects the encryption algorithm to use from those offered by the | 163 164 For protocol 2, forward security is provided through a Diffie-Hellman key 165 agreement. This key agreement results in a shared session key. The rest 166 of the session is encrypted using a symmetric cipher, currently 128-bit 167 AES, Blowfish, 3DES, CAST128, Arcfour, 192-bit AES, or 256-bit AES. The 168 client selects the encryption algorithm to use from those offered by the |
| 167 server. Additionally, session integrity is provided through a crypto- 168 graphic message authentication code (hmac-md5, hmac-sha1, umac-64 or 169 hmac-ripemd160). | 169 server. Additionally, session integrity is provided through a 170 cryptographic message authentication code (hmac-md5, hmac-sha1, umac-64 171 or hmac-ripemd160). |
| 170 171 Finally, the server and the client enter an authentication dialog. The | 172 173 Finally, the server and the client enter an authentication dialog. The |
| 172 client tries to authenticate itself using host-based authentication, pub- 173 lic key authentication, challenge-response authentication, or password | 174 client tries to authenticate itself using host-based authentication, 175 public key authentication, challenge-response authentication, or password |
| 174 authentication. 175 176 Regardless of the authentication type, the account is checked to ensure 177 that it is accessible. An account is not accessible if it is locked, | 176 authentication. 177 178 Regardless of the authentication type, the account is checked to ensure 179 that it is accessible. An account is not accessible if it is locked, |
| 178 listed in DenyUsers or its group is listed in DenyGroups . The defini- 179 tion of a locked account is system dependant. Some platforms have their 180 own account database (eg AIX) and some modify the passwd field ( `*LK*' 181 on Solaris and UnixWare, `*' on HP-UX, containing `Nologin' on Tru64, a 182 leading `*LOCKED*' on FreeBSD and a leading `!' on most Linuxes). If 183 there is a requirement to disable password authentication for the account 184 while allowing still public-key, then the passwd field should be set to 185 something other than these values (eg `NP' or `*NP*' ). | 180 listed in DenyUsers or its group is listed in DenyGroups . The 181 definition of a locked account is system dependant. Some platforms have 182 their own account database (eg AIX) and some modify the passwd field ( 183 `*LK*' on Solaris and UnixWare, `*' on HP-UX, containing `Nologin' on 184 Tru64, a leading `*LOCKED*' on FreeBSD and a leading `!' on most 185 Linuxes). If there is a requirement to disable password authentication 186 for the account while allowing still public-key, then the passwd field 187 should be set to something other than these values (eg `NP' or `*NP*' ). |
| 186 187 If the client successfully authenticates itself, a dialog for preparing 188 the session is entered. At this time the client may request things like | 188 189 If the client successfully authenticates itself, a dialog for preparing 190 the session is entered. At this time the client may request things like |
| 189 allocating a pseudo-tty, forwarding X11 connections, forwarding TCP con- 190 nections, or forwarding the authentication agent connection over the se- 191 cure channel. | 191 allocating a pseudo-tty, forwarding X11 connections, forwarding TCP 192 connections, or forwarding the authentication agent connection over the 193 secure channel. |
| 192 193 After this, the client either requests a shell or execution of a command. 194 The sides then enter session mode. In this mode, either side may send 195 data at any time, and such data is forwarded to/from the shell or command 196 on the server side, and the user terminal in the client side. 197 | 194 195 After this, the client either requests a shell or execution of a command. 196 The sides then enter session mode. In this mode, either side may send 197 data at any time, and such data is forwarded to/from the shell or command 198 on the server side, and the user terminal in the client side. 199 |
| 198 When the user program terminates and all forwarded X11 and other connec- 199 tions have been closed, the server sends command exit status to the | 200 When the user program terminates and all forwarded X11 and other 201 connections have been closed, the server sends command exit status to the |
| 200 client, and both sides exit. 201 202LOGIN PROCESS 203 When a user successfully logs in, sshd does the following: 204 205 1. If the login is on a tty, and no command has been specified, 206 prints last login time and /etc/motd (unless prevented in the 207 configuration file or by ~/.hushlogin; see the FILES section). --- 17 unchanged lines hidden (view full) --- 225 runs it; otherwise runs xauth. The ``rc'' files are given the 226 X11 authentication protocol and cookie in standard input. See 227 SSHRC, below. 228 229 9. Runs user's shell or command. 230 231SSHRC 232 If the file ~/.ssh/rc exists, sh(1) runs it after reading the environment | 202 client, and both sides exit. 203 204LOGIN PROCESS 205 When a user successfully logs in, sshd does the following: 206 207 1. If the login is on a tty, and no command has been specified, 208 prints last login time and /etc/motd (unless prevented in the 209 configuration file or by ~/.hushlogin; see the FILES section). --- 17 unchanged lines hidden (view full) --- 227 runs it; otherwise runs xauth. The ``rc'' files are given the 228 X11 authentication protocol and cookie in standard input. See 229 SSHRC, below. 230 231 9. Runs user's shell or command. 232 233SSHRC 234 If the file ~/.ssh/rc exists, sh(1) runs it after reading the environment |
| 233 files but before starting the user's shell or command. It must not pro- 234 duce any output on stdout; stderr must be used instead. If X11 forward- 235 ing is in use, it will receive the "proto cookie" pair in its standard 236 input (and DISPLAY in its environment). The script must call xauth(1) 237 because sshd will not run xauth automatically to add X11 cookies. | 235 files but before starting the user's shell or command. It must not 236 produce any output on stdout; stderr must be used instead. If X11 237 forwarding is in use, it will receive the "proto cookie" pair in its 238 standard input (and DISPLAY in its environment). The script must call 239 xauth(1) because sshd will not run xauth automatically to add X11 240 cookies. |
| 238 239 The primary purpose of this file is to run any initialization routines 240 which may be needed before the user's home directory becomes accessible; 241 AFS is a particular example of such an environment. 242 243 This file will probably contain some initialization code followed by 244 something similar to: 245 --- 12 unchanged lines hidden (view full) --- 258 exist either, xauth is used to add the cookie. 259 260AUTHORIZED_KEYS FILE FORMAT 261 AuthorizedKeysFile specifies the file containing public keys for public 262 key authentication; if none is specified, the default is 263 ~/.ssh/authorized_keys. Each line of the file contains one key (empty 264 lines and lines starting with a `#' are ignored as comments). Protocol 1 265 public keys consist of the following space-separated fields: options, | 241 242 The primary purpose of this file is to run any initialization routines 243 which may be needed before the user's home directory becomes accessible; 244 AFS is a particular example of such an environment. 245 246 This file will probably contain some initialization code followed by 247 something similar to: 248 --- 12 unchanged lines hidden (view full) --- 261 exist either, xauth is used to add the cookie. 262 263AUTHORIZED_KEYS FILE FORMAT 264 AuthorizedKeysFile specifies the file containing public keys for public 265 key authentication; if none is specified, the default is 266 ~/.ssh/authorized_keys. Each line of the file contains one key (empty 267 lines and lines starting with a `#' are ignored as comments). Protocol 1 268 public keys consist of the following space-separated fields: options, |
| 266 bits, exponent, modulus, comment. Protocol 2 public key consist of: op- 267 tions, keytype, base64-encoded key, comment. The options field is op- 268 tional; its presence is determined by whether the line starts with a num- 269 ber or not (the options field never starts with a number). The bits, ex- 270 ponent, modulus, and comment fields give the RSA key for protocol version 271 1; the comment field is not used for anything (but may be convenient for 272 the user to identify the key). For protocol version 2 the keytype is 273 ``ssh-dss'' or ``ssh-rsa''. | 269 bits, exponent, modulus, comment. Protocol 2 public key consist of: 270 options, keytype, base64-encoded key, comment. The options field is 271 optional; its presence is determined by whether the line starts with a 272 number or not (the options field never starts with a number). The bits, 273 exponent, modulus, and comment fields give the RSA key for protocol 274 version 1; the comment field is not used for anything (but may be 275 convenient for the user to identify the key). For protocol version 2 the 276 keytype is ``ssh-dss'' or ``ssh-rsa''. |
| 274 | 277 |
| 275 Note that lines in this file are usually several hundred bytes long (be- 276 cause of the size of the public key encoding) up to a limit of 8 kilo- 277 bytes, which permits DSA keys up to 8 kilobits and RSA keys up to 16 | 278 Note that lines in this file are usually several hundred bytes long 279 (because of the size of the public key encoding) up to a limit of 8 280 kilobytes, which permits DSA keys up to 8 kilobits and RSA keys up to 16 |
| 278 kilobits. You don't want to type them in; instead, copy the 279 identity.pub, id_dsa.pub, or the id_rsa.pub file and edit it. 280 281 sshd enforces a minimum RSA key modulus size for protocol 1 and protocol 282 2 keys of 768 bits. 283 | 281 kilobits. You don't want to type them in; instead, copy the 282 identity.pub, id_dsa.pub, or the id_rsa.pub file and edit it. 283 284 sshd enforces a minimum RSA key modulus size for protocol 1 and protocol 285 2 keys of 768 bits. 286 |
| 284 The options (if present) consist of comma-separated option specifica- 285 tions. No spaces are permitted, except within double quotes. The fol- 286 lowing option specifications are supported (note that option keywords are 287 case-insensitive): | 287 The options (if present) consist of comma-separated option 288 specifications. No spaces are permitted, except within double quotes. 289 The following option specifications are supported (note that option 290 keywords are case-insensitive): |
| 288 289 cert-authority 290 Specifies that the listed key is a certification authority (CA) | 291 292 cert-authority 293 Specifies that the listed key is a certification authority (CA) |
| 291 that is trusted to validate signed certificates for user authen- 292 tication. | 294 that is trusted to validate signed certificates for user 295 authentication. |
| 293 294 Certificates may encode access restrictions similar to these key 295 options. If both certificate restrictions and key options are 296 present, the most restrictive union of the two is applied. 297 298 command="command" 299 Specifies that the command is executed whenever this key is used 300 for authentication. The command supplied by the user (if any) is 301 ignored. The command is run on a pty if the client requests a | 296 297 Certificates may encode access restrictions similar to these key 298 options. If both certificate restrictions and key options are 299 present, the most restrictive union of the two is applied. 300 301 command="command" 302 Specifies that the command is executed whenever this key is used 303 for authentication. The command supplied by the user (if any) is 304 ignored. The command is run on a pty if the client requests a |
| 302 pty; otherwise it is run without a tty. If an 8-bit clean chan- 303 nel is required, one must not request a pty or should specify no- 304 pty. A quote may be included in the command by quoting it with a 305 backslash. This option might be useful to restrict certain pub- 306 lic keys to perform just a specific operation. An example might 307 be a key that permits remote backups but nothing else. Note that 308 the client may specify TCP and/or X11 forwarding unless they are 309 explicitly prohibited. The command originally supplied by the 310 client is available in the SSH_ORIGINAL_COMMAND environment vari- 311 able. Note that this option applies to shell, command or subsys- 312 tem execution. Also note that this command may be superseded by 313 either a sshd_config(5) ForceCommand directive or a command em- 314 bedded in a certificate. | 305 pty; otherwise it is run without a tty. If an 8-bit clean 306 channel is required, one must not request a pty or should specify 307 no-pty. A quote may be included in the command by quoting it 308 with a backslash. This option might be useful to restrict 309 certain public keys to perform just a specific operation. An 310 example might be a key that permits remote backups but nothing 311 else. Note that the client may specify TCP and/or X11 forwarding 312 unless they are explicitly prohibited. The command originally 313 supplied by the client is available in the SSH_ORIGINAL_COMMAND 314 environment variable. Note that this option applies to shell, 315 command or subsystem execution. Also note that this command may 316 be superseded by either a sshd_config(5) ForceCommand directive 317 or a command embedded in a certificate. |
| 315 316 environment="NAME=value" 317 Specifies that the string is to be added to the environment when 318 logging in using this key. Environment variables set this way 319 override other default environment values. Multiple options of 320 this type are permitted. Environment processing is disabled by 321 default and is controlled via the PermitUserEnvironment option. 322 This option is automatically disabled if UseLogin is enabled. 323 324 from="pattern-list" 325 Specifies that in addition to public key authentication, either 326 the canonical name of the remote host or its IP address must be 327 present in the comma-separated list of patterns. See PATTERNS in 328 ssh_config(5) for more information on patterns. 329 | 318 319 environment="NAME=value" 320 Specifies that the string is to be added to the environment when 321 logging in using this key. Environment variables set this way 322 override other default environment values. Multiple options of 323 this type are permitted. Environment processing is disabled by 324 default and is controlled via the PermitUserEnvironment option. 325 This option is automatically disabled if UseLogin is enabled. 326 327 from="pattern-list" 328 Specifies that in addition to public key authentication, either 329 the canonical name of the remote host or its IP address must be 330 present in the comma-separated list of patterns. See PATTERNS in 331 ssh_config(5) for more information on patterns. 332 |
| 330 In addition to the wildcard matching that may be applied to host- 331 names or addresses, a from stanza may match IP addresses using 332 CIDR address/masklen notation. | 333 In addition to the wildcard matching that may be applied to 334 hostnames or addresses, a from stanza may match IP addresses 335 using CIDR address/masklen notation. |
| 333 334 The purpose of this option is to optionally increase security: 335 public key authentication by itself does not trust the network or 336 name servers or anything (but the key); however, if somebody 337 somehow steals the key, the key permits an intruder to log in 338 from anywhere in the world. This additional option makes using a 339 stolen key more difficult (name servers and/or routers would have 340 to be compromised in addition to just the key). --- 12 unchanged lines hidden (view full) --- 353 no-user-rc 354 Disables execution of ~/.ssh/rc. 355 356 no-X11-forwarding 357 Forbids X11 forwarding when this key is used for authentication. 358 Any X11 forward requests by the client will return an error. 359 360 permitopen="host:port" | 336 337 The purpose of this option is to optionally increase security: 338 public key authentication by itself does not trust the network or 339 name servers or anything (but the key); however, if somebody 340 somehow steals the key, the key permits an intruder to log in 341 from anywhere in the world. This additional option makes using a 342 stolen key more difficult (name servers and/or routers would have 343 to be compromised in addition to just the key). --- 12 unchanged lines hidden (view full) --- 356 no-user-rc 357 Disables execution of ~/.ssh/rc. 358 359 no-X11-forwarding 360 Forbids X11 forwarding when this key is used for authentication. 361 Any X11 forward requests by the client will return an error. 362 363 permitopen="host:port" |
| 361 Limit local ``ssh -L'' port forwarding such that it may only con- 362 nect to the specified host and port. IPv6 addresses can be spec- 363 ified with an alternative syntax: host/port. Multiple permitopen 364 options may be applied separated by commas. No pattern matching 365 is performed on the specified hostnames, they must be literal do- 366 mains or addresses. | 364 Limit local ``ssh -L'' port forwarding such that it may only 365 connect to the specified host and port. IPv6 addresses can be 366 specified by enclosing the address in square brackets. Multiple 367 permitopen options may be applied separated by commas. No 368 pattern matching is performed on the specified hostnames, they 369 must be literal domains or addresses. |
| 367 | 370 |
| 371 principals="principals" 372 On a cert-authority line, specifies allowed principals for 373 certificate authentication as a comma-separated list. At least 374 one name from the list must appear in the certificate's list of 375 principals for the certificate to be accepted. This option is 376 ignored for keys that are not marked as trusted certificate 377 signers using the cert-authority option. 378 |
|
| 368 tunnel="n" 369 Force a tun(4) device on the server. Without this option, the | 379 tunnel="n" 380 Force a tun(4) device on the server. Without this option, the |
| 370 next available device will be used if the client requests a tun- 371 nel. | 381 next available device will be used if the client requests a 382 tunnel. |
| 372 373 An example authorized_keys file: 374 375 # Comments allowed at start of line 376 ssh-rsa AAAAB3Nza...LiPk== user@example.net 377 from="*.sales.example.net,!pc.sales.example.net" ssh-rsa 378 AAAAB2...19Q== john@example.net 379 command="dump /home",no-pty,no-port-forwarding ssh-dss 380 AAAAC3...51R== example.net 381 permitopen="192.0.2.1:80",permitopen="192.0.2.2:25" ssh-dss 382 AAAAB5...21S== 383 tunnel="0",command="sh /etc/netstart tun0" ssh-rsa AAAA...== 384 jane@example.net 385 386SSH_KNOWN_HOSTS FILE FORMAT 387 The /etc/ssh/ssh_known_hosts and ~/.ssh/known_hosts files contain host 388 public keys for all known hosts. The global file should be prepared by | 383 384 An example authorized_keys file: 385 386 # Comments allowed at start of line 387 ssh-rsa AAAAB3Nza...LiPk== user@example.net 388 from="*.sales.example.net,!pc.sales.example.net" ssh-rsa 389 AAAAB2...19Q== john@example.net 390 command="dump /home",no-pty,no-port-forwarding ssh-dss 391 AAAAC3...51R== example.net 392 permitopen="192.0.2.1:80",permitopen="192.0.2.2:25" ssh-dss 393 AAAAB5...21S== 394 tunnel="0",command="sh /etc/netstart tun0" ssh-rsa AAAA...== 395 jane@example.net 396 397SSH_KNOWN_HOSTS FILE FORMAT 398 The /etc/ssh/ssh_known_hosts and ~/.ssh/known_hosts files contain host 399 public keys for all known hosts. The global file should be prepared by |
| 389 the administrator (optional), and the per-user file is maintained auto- 390 matically: whenever the user connects from an unknown host, its key is 391 added to the per-user file. | 400 the administrator (optional), and the per-user file is maintained 401 automatically: whenever the user connects from an unknown host, its key 402 is added to the per-user file. |
| 392 | 403 |
| 393 Each line in these files contains the following fields: markers (option- 394 al), hostnames, bits, exponent, modulus, comment. The fields are sepa- 395 rated by spaces. | 404 Each line in these files contains the following fields: markers 405 (optional), hostnames, bits, exponent, modulus, comment. The fields are 406 separated by spaces. |
| 396 397 The marker is optional, but if it is present then it must be one of 398 ``@cert-authority'', to indicate that the line contains a certification 399 authority (CA) key, or ``@revoked'', to indicate that the key contained 400 on the line is revoked and must not ever be accepted. Only one marker 401 should be used on a key line. 402 | 407 408 The marker is optional, but if it is present then it must be one of 409 ``@cert-authority'', to indicate that the line contains a certification 410 authority (CA) key, or ``@revoked'', to indicate that the key contained 411 on the line is revoked and must not ever be accepted. Only one marker 412 should be used on a key line. 413 |
| 403 Hostnames is a comma-separated list of patterns (`*' and `?' act as wild- 404 cards); each pattern in turn is matched against the canonical host name 405 (when authenticating a client) or against the user-supplied name (when 406 authenticating a server). A pattern may also be preceded by `!' to indi- 407 cate negation: if the host name matches a negated pattern, it is not ac- 408 cepted (by that line) even if it matched another pattern on the line. A 409 hostname or address may optionally be enclosed within `[' and `]' brack- 410 ets then followed by `:' and a non-standard port number. | 414 Hostnames is a comma-separated list of patterns (`*' and `?' act as 415 wildcards); each pattern in turn is matched against the canonical host 416 name (when authenticating a client) or against the user-supplied name 417 (when authenticating a server). A pattern may also be preceded by `!' to 418 indicate negation: if the host name matches a negated pattern, it is not 419 accepted (by that line) even if it matched another pattern on the line. 420 A hostname or address may optionally be enclosed within `[' and `]' 421 brackets then followed by `:' and a non-standard port number. |
| 411 412 Alternately, hostnames may be stored in a hashed form which hides host 413 names and addresses should the file's contents be disclosed. Hashed | 422 423 Alternately, hostnames may be stored in a hashed form which hides host 424 names and addresses should the file's contents be disclosed. Hashed |
| 414 hostnames start with a `|' character. Only one hashed hostname may ap- 415 pear on a single line and none of the above negation or wildcard opera- 416 tors may be applied. | 425 hostnames start with a `|' character. Only one hashed hostname may 426 appear on a single line and none of the above negation or wildcard 427 operators may be applied. |
| 417 418 Bits, exponent, and modulus are taken directly from the RSA host key; 419 they can be obtained, for example, from /etc/ssh/ssh_host_key.pub. The 420 optional comment field continues to the end of the line, and is not used. 421 422 Lines starting with `#' and empty lines are ignored as comments. 423 424 When performing host authentication, authentication is accepted if any 425 matching line has the proper key; either one that matches exactly or, if 426 the server has presented a certificate for authentication, the key of the 427 certification authority that signed the certificate. For a key to be 428 trusted as a certification authority, it must use the ``@cert-authority'' 429 marker described above. 430 431 The known hosts file also provides a facility to mark keys as revoked, 432 for example when it is known that the associated private key has been 433 stolen. Revoked keys are specified by including the ``@revoked'' marker | 428 429 Bits, exponent, and modulus are taken directly from the RSA host key; 430 they can be obtained, for example, from /etc/ssh/ssh_host_key.pub. The 431 optional comment field continues to the end of the line, and is not used. 432 433 Lines starting with `#' and empty lines are ignored as comments. 434 435 When performing host authentication, authentication is accepted if any 436 matching line has the proper key; either one that matches exactly or, if 437 the server has presented a certificate for authentication, the key of the 438 certification authority that signed the certificate. For a key to be 439 trusted as a certification authority, it must use the ``@cert-authority'' 440 marker described above. 441 442 The known hosts file also provides a facility to mark keys as revoked, 443 for example when it is known that the associated private key has been 444 stolen. Revoked keys are specified by including the ``@revoked'' marker |
| 434 at the beginning of the key line, and are never accepted for authentica- 435 tion or as certification authorities, but instead will produce a warning 436 from ssh(1) when they are encountered. | 445 at the beginning of the key line, and are never accepted for 446 authentication or as certification authorities, but instead will produce 447 a warning from ssh(1) when they are encountered. |
| 437 | 448 |
| 438 It is permissible (but not recommended) to have several lines or differ- 439 ent host keys for the same names. This will inevitably happen when short 440 forms of host names from different domains are put in the file. It is 441 possible that the files contain conflicting information; authentication 442 is accepted if valid information can be found from either file. | 449 It is permissible (but not recommended) to have several lines or 450 different host keys for the same names. This will inevitably happen when 451 short forms of host names from different domains are put in the file. It 452 is possible that the files contain conflicting information; 453 authentication is accepted if valid information can be found from either 454 file. |
| 443 444 Note that the lines in these files are typically hundreds of characters 445 long, and you definitely don't want to type in the host keys by hand. 446 Rather, generate them by a script, ssh-keyscan(1) or by taking 447 /etc/ssh/ssh_host_key.pub and adding the host names at the front. 448 ssh-keygen(1) also offers some basic automated editing for | 455 456 Note that the lines in these files are typically hundreds of characters 457 long, and you definitely don't want to type in the host keys by hand. 458 Rather, generate them by a script, ssh-keyscan(1) or by taking 459 /etc/ssh/ssh_host_key.pub and adding the host names at the front. 460 ssh-keygen(1) also offers some basic automated editing for |
| 449 ~/.ssh/known_hosts including removing hosts matching a host name and con- 450 verting all host names to their hashed representations. | 461 ~/.ssh/known_hosts including removing hosts matching a host name and 462 converting all host names to their hashed representations. |
| 451 452 An example ssh_known_hosts file: 453 454 # Comments allowed at start of line 455 closenet,...,192.0.2.53 1024 37 159...93 closenet.example.net 456 cvs.example.net,192.0.2.10 ssh-rsa AAAA1234.....= 457 # A hashed hostname 458 |1|JfKTdBh7rNbXkVAQCRp4OQoPfmI=|USECr3SWf1JUPsms5AqfD5QfxkM= ssh-rsa 459 AAAA1234.....= 460 # A revoked key 461 @revoked * ssh-rsa AAAAB5W... 462 # A CA key, accepted for any host in *.mydomain.com or *.mydomain.org 463 @cert-authority *.mydomain.org,*.mydomain.com ssh-rsa AAAAB5W... 464 465FILES 466 ~/.hushlogin 467 This file is used to suppress printing the last login time and | 463 464 An example ssh_known_hosts file: 465 466 # Comments allowed at start of line 467 closenet,...,192.0.2.53 1024 37 159...93 closenet.example.net 468 cvs.example.net,192.0.2.10 ssh-rsa AAAA1234.....= 469 # A hashed hostname 470 |1|JfKTdBh7rNbXkVAQCRp4OQoPfmI=|USECr3SWf1JUPsms5AqfD5QfxkM= ssh-rsa 471 AAAA1234.....= 472 # A revoked key 473 @revoked * ssh-rsa AAAAB5W... 474 # A CA key, accepted for any host in *.mydomain.com or *.mydomain.org 475 @cert-authority *.mydomain.org,*.mydomain.com ssh-rsa AAAAB5W... 476 477FILES 478 ~/.hushlogin 479 This file is used to suppress printing the last login time and |
| 468 /etc/motd, if PrintLastLog and PrintMotd, respectively, are en- 469 abled. It does not suppress printing of the banner specified by 470 Banner. | 480 /etc/motd, if PrintLastLog and PrintMotd, respectively, are 481 enabled. It does not suppress printing of the banner specified 482 by Banner. |
| 471 472 ~/.rhosts 473 This file is used for host-based authentication (see ssh(1) for 474 more information). On some machines this file may need to be | 483 484 ~/.rhosts 485 This file is used for host-based authentication (see ssh(1) for 486 more information). On some machines this file may need to be |
| 475 world-readable if the user's home directory is on an NFS parti- 476 tion, because sshd reads it as root. Additionally, this file 477 must be owned by the user, and must not have write permissions 478 for anyone else. The recommended permission for most machines is 479 read/write for the user, and not accessible by others. | 487 world-readable if the user's home directory is on an NFS 488 partition, because sshd reads it as root. Additionally, this 489 file must be owned by the user, and must not have write 490 permissions for anyone else. The recommended permission for most 491 machines is read/write for the user, and not accessible by 492 others. |
| 480 481 ~/.shosts 482 This file is used in exactly the same way as .rhosts, but allows 483 host-based authentication without permitting login with 484 rlogin/rsh. 485 486 ~/.ssh/ | 493 494 ~/.shosts 495 This file is used in exactly the same way as .rhosts, but allows 496 host-based authentication without permitting login with 497 rlogin/rsh. 498 499 ~/.ssh/ |
| 487 This directory is the default location for all user-specific con- 488 figuration and authentication information. There is no general 489 requirement to keep the entire contents of this directory secret, 490 but the recommended permissions are read/write/execute for the 491 user, and not accessible by others. | 500 This directory is the default location for all user-specific 501 configuration and authentication information. There is no 502 general requirement to keep the entire contents of this directory 503 secret, but the recommended permissions are read/write/execute 504 for the user, and not accessible by others. |
| 492 493 ~/.ssh/authorized_keys 494 Lists the public keys (RSA/DSA) that can be used for logging in 495 as this user. The format of this file is described above. The 496 content of the file is not highly sensitive, but the recommended 497 permissions are read/write for the user, and not accessible by 498 others. 499 500 If this file, the ~/.ssh directory, or the user's home directory 501 are writable by other users, then the file could be modified or | 505 506 ~/.ssh/authorized_keys 507 Lists the public keys (RSA/DSA) that can be used for logging in 508 as this user. The format of this file is described above. The 509 content of the file is not highly sensitive, but the recommended 510 permissions are read/write for the user, and not accessible by 511 others. 512 513 If this file, the ~/.ssh directory, or the user's home directory 514 are writable by other users, then the file could be modified or |
| 502 replaced by unauthorized users. In this case, sshd will not al- 503 low it to be used unless the StrictModes option has been set to | 515 replaced by unauthorized users. In this case, sshd will not 516 allow it to be used unless the StrictModes option has been set to |
| 504 ``no''. 505 506 ~/.ssh/environment 507 This file is read into the environment at login (if it exists). 508 It can only contain empty lines, comment lines (that start with 509 `#'), and assignment lines of the form name=value. The file 510 should be writable only by the user; it need not be readable by 511 anyone else. Environment processing is disabled by default and --- 8 unchanged lines hidden (view full) --- 520 521 ~/.ssh/rc 522 Contains initialization routines to be run before the user's home 523 directory becomes accessible. This file should be writable only 524 by the user, and need not be readable by anyone else. 525 526 /etc/hosts.allow 527 /etc/hosts.deny | 517 ``no''. 518 519 ~/.ssh/environment 520 This file is read into the environment at login (if it exists). 521 It can only contain empty lines, comment lines (that start with 522 `#'), and assignment lines of the form name=value. The file 523 should be writable only by the user; it need not be readable by 524 anyone else. Environment processing is disabled by default and --- 8 unchanged lines hidden (view full) --- 533 534 ~/.ssh/rc 535 Contains initialization routines to be run before the user's home 536 directory becomes accessible. This file should be writable only 537 by the user, and need not be readable by anyone else. 538 539 /etc/hosts.allow 540 /etc/hosts.deny |
| 528 Access controls that should be enforced by tcp-wrappers are de- 529 fined here. Further details are described in hosts_access(5). | 541 Access controls that should be enforced by tcp-wrappers are 542 defined here. Further details are described in hosts_access(5). |
| 530 531 /etc/hosts.equiv 532 This file is for host-based authentication (see ssh(1)). It 533 should only be writable by root. 534 535 /etc/moduli 536 Contains Diffie-Hellman groups used for the "Diffie-Hellman Group 537 Exchange". The file format is described in moduli(5). 538 539 /etc/motd 540 See motd(5). 541 542 /etc/nologin 543 If this file exists, sshd refuses to let anyone except root log 544 in. The contents of the file are displayed to anyone trying to 545 log in, and non-root connections are refused. The file should be 546 world-readable. 547 548 /etc/shosts.equiv | 543 544 /etc/hosts.equiv 545 This file is for host-based authentication (see ssh(1)). It 546 should only be writable by root. 547 548 /etc/moduli 549 Contains Diffie-Hellman groups used for the "Diffie-Hellman Group 550 Exchange". The file format is described in moduli(5). 551 552 /etc/motd 553 See motd(5). 554 555 /etc/nologin 556 If this file exists, sshd refuses to let anyone except root log 557 in. The contents of the file are displayed to anyone trying to 558 log in, and non-root connections are refused. The file should be 559 world-readable. 560 561 /etc/shosts.equiv |
| 549 This file is used in exactly the same way as hosts.equiv, but al- 550 lows host-based authentication without permitting login with | 562 This file is used in exactly the same way as hosts.equiv, but 563 allows host-based authentication without permitting login with |
| 551 rlogin/rsh. 552 553 /etc/ssh/ssh_host_key 554 /etc/ssh/ssh_host_dsa_key 555 /etc/ssh/ssh_host_rsa_key 556 These three files contain the private parts of the host keys. 557 These files should only be owned by root, readable only by root, 558 and not accessible to others. Note that sshd does not start if --- 7 unchanged lines hidden (view full) --- 566 Their contents should match the respective private parts. These 567 files are not really used for anything; they are provided for the 568 convenience of the user so their contents can be copied to known 569 hosts files. These files are created using ssh-keygen(1). 570 571 /etc/ssh/ssh_known_hosts 572 Systemwide list of known host keys. This file should be prepared 573 by the system administrator to contain the public host keys of | 564 rlogin/rsh. 565 566 /etc/ssh/ssh_host_key 567 /etc/ssh/ssh_host_dsa_key 568 /etc/ssh/ssh_host_rsa_key 569 These three files contain the private parts of the host keys. 570 These files should only be owned by root, readable only by root, 571 and not accessible to others. Note that sshd does not start if --- 7 unchanged lines hidden (view full) --- 579 Their contents should match the respective private parts. These 580 files are not really used for anything; they are provided for the 581 convenience of the user so their contents can be copied to known 582 hosts files. These files are created using ssh-keygen(1). 583 584 /etc/ssh/ssh_known_hosts 585 Systemwide list of known host keys. This file should be prepared 586 by the system administrator to contain the public host keys of |
| 574 all machines in the organization. The format of this file is de- 575 scribed above. This file should be writable only by root/the | 587 all machines in the organization. The format of this file is 588 described above. This file should be writable only by root/the |
| 576 owner and should be world-readable. 577 578 /etc/ssh/sshd_config | 589 owner and should be world-readable. 590 591 /etc/ssh/sshd_config |
| 579 Contains configuration data for sshd. The file format and con- 580 figuration options are described in sshd_config(5). | 592 Contains configuration data for sshd. The file format and 593 configuration options are described in sshd_config(5). |
| 581 582 /etc/ssh/sshrc 583 Similar to ~/.ssh/rc, it can be used to specify machine-specific 584 login-time initializations globally. This file should be 585 writable only by root, and should be world-readable. 586 587 /var/empty 588 chroot(2) directory used by sshd during privilege separation in 589 the pre-authentication phase. The directory should not contain 590 any files and must be owned by root and not group or world- 591 writable. 592 593 /var/run/sshd.pid 594 Contains the process ID of the sshd listening for connections (if 595 there are several daemons running concurrently for different 596 ports, this contains the process ID of the one started last). | 594 595 /etc/ssh/sshrc 596 Similar to ~/.ssh/rc, it can be used to specify machine-specific 597 login-time initializations globally. This file should be 598 writable only by root, and should be world-readable. 599 600 /var/empty 601 chroot(2) directory used by sshd during privilege separation in 602 the pre-authentication phase. The directory should not contain 603 any files and must be owned by root and not group or world- 604 writable. 605 606 /var/run/sshd.pid 607 Contains the process ID of the sshd listening for connections (if 608 there are several daemons running concurrently for different 609 ports, this contains the process ID of the one started last). |
| 597 The content of this file is not sensitive; it can be world-read- 598 able. | 610 The content of this file is not sensitive; it can be world- 611 readable. |
| 599 600SEE ALSO 601 scp(1), sftp(1), ssh(1), ssh-add(1), ssh-agent(1), ssh-keygen(1), 602 ssh-keyscan(1), chroot(2), hosts_access(5), login.conf(5), moduli(5), 603 sshd_config(5), inetd(8), sftp-server(8) 604 605AUTHORS 606 OpenSSH is a derivative of the original and free ssh 1.2.12 release by 607 Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo | 612 613SEE ALSO 614 scp(1), sftp(1), ssh(1), ssh-add(1), ssh-agent(1), ssh-keygen(1), 615 ssh-keyscan(1), chroot(2), hosts_access(5), login.conf(5), moduli(5), 616 sshd_config(5), inetd(8), sftp-server(8) 617 618AUTHORS 619 OpenSSH is a derivative of the original and free ssh 1.2.12 release by 620 Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo |
| 608 de Raadt and Dug Song removed many bugs, re-added newer features and cre- 609 ated OpenSSH. Markus Friedl contributed the support for SSH protocol | 621 de Raadt and Dug Song removed many bugs, re-added newer features and 622 created OpenSSH. Markus Friedl contributed the support for SSH protocol |
| 610 versions 1.5 and 2.0. Niels Provos and Markus Friedl contributed support 611 for privilege separation. 612 613CAVEATS | 623 versions 1.5 and 2.0. Niels Provos and Markus Friedl contributed support 624 for privilege separation. 625 626CAVEATS |
| 614 System security is not improved unless rshd, rlogind, and rexecd are dis- 615 abled (thus completely disabling rlogin and rsh into the machine). | 627 System security is not improved unless rshd, rlogind, and rexecd are 628 disabled (thus completely disabling rlogin and rsh into the machine). |
| 616 | 629 |
| 617OpenBSD 4.7 March 5, 2010 10 | 630OpenBSD 4.8 August 4, 2010 OpenBSD 4.8 |