options.h

   1 /* Dropbear SSH
   2  * Copyright (c) 2002,2003 Matt Johnston
   3  * All rights reserved. See LICENSE for the license. */
   4
   5 #ifndef _OPTIONS_H_
   6 #define _OPTIONS_H_
   7
   8 /******************************************************************
   9  * Define compile-time options below - the "#ifndef DROPBEAR_XXX .... #endif"
  10  * parts are to allow for commandline -DDROPBEAR_XXX options etc.
  11  ******************************************************************/
  12
  13 #ifndef DROPBEAR_DEFPORT
  14 #define DROPBEAR_DEFPORT "22"
  15 #endif
  16
  17 #ifndef DROPBEAR_DEFADDRESS
  18 /* Listen on all interfaces */
  19 #define DROPBEAR_DEFADDRESS ""
  20 #endif
  21
  22 /* Default hostkey paths - these can be specified on the command line */
  23 #ifndef DSS_PRIV_FILENAME
  24 #define DSS_PRIV_FILENAME "/etc/dropbear/dropbear_dss_host_key"
  25 #endif
  26 #ifndef RSA_PRIV_FILENAME
  27 #define RSA_PRIV_FILENAME "/etc/dropbear/dropbear_rsa_host_key"
  28 #endif
  29
  30 /* Set NON_INETD_MODE if you require daemon functionality (ie Dropbear listens
  31  * on chosen ports and keeps accepting connections. This is the default.
  32  *
  33  * Set INETD_MODE if you want to be able to run Dropbear with inetd (or
  34  * similar), where it will use stdin/stdout for connections, and each process
  35  * lasts for a single connection. Dropbear should be invoked with the -i flag
  36  * for inetd, and can only accept IPv4 connections.
  37  *
  38  * Both of these flags can be defined at once, don't compile without at least
  39  * one of them. */
  40 #define NON_INETD_MODE
  41 #define INETD_MODE
  42
  43 /* Setting this disables the fast exptmod bignum code. It saves ~5kB, but is
  44  * perhaps 20% slower for pubkey operations (it is probably worth experimenting
  45  * if you want to use this) */
  46 /*#define NO_FAST_EXPTMOD*/
  47
  48 /* Set this if you want to use the DROPBEAR_SMALL_CODE option. This can save
  49 several kB in binary size however will make the symmetrical ciphers and hashes
  50 slower, perhaps by 50%. Recommended for small systems that aren't doing
  51 much traffic. */
  52 /*#define DROPBEAR_SMALL_CODE*/
  53
  54 /* Enable X11 Forwarding - server only */
  55 #define ENABLE_X11FWD
  56
  57 /* Enable TCP Fowarding */
  58 /* 'Local' is "-L" style (client listening port forwarded via server)
  59  * 'Remote' is "-R" style (server listening port forwarded via client) */
  60
  61 #define ENABLE_CLI_LOCALTCPFWD
  62 #define ENABLE_CLI_REMOTETCPFWD
  63
  64 #define ENABLE_SVR_LOCALTCPFWD
  65 #define ENABLE_SVR_REMOTETCPFWD
  66
  67 /* Enable Authentication Agent Forwarding - server only for now */
  68 #define ENABLE_SVR_AGENTFWD
  69 #define ENABLE_CLI_AGENTFWD
  70
  71
  72 /* Note: Both ENABLE_CLI_PROXYCMD and ENABLE_CLI_NETCAT must be set to
  73  * allow multihop dbclient connections */
  74
  75 /* Allow using -J <proxycommand> to run the connection through a
  76    pipe to a program, rather the normal TCP connection */
  77 #define ENABLE_CLI_PROXYCMD
  78
  79 /* Enable "Netcat mode" option. This will forward standard input/output
  80  * to a remote TCP-forwarded connection */
  81 #define ENABLE_CLI_NETCAT
  82
  83 /* Encryption - at least one required.
  84  * Protocol RFC requires 3DES and recommends AES128 for interoperability.
  85  * Including multiple keysize variants the same cipher
  86  * (eg AES256 as well as AES128) will result in a minimal size increase.*/
  87 #define DROPBEAR_AES128
  88 #define DROPBEAR_3DES
  89 #define DROPBEAR_AES256
  90 /* Compiling in Blowfish will add ~6kB to runtime heap memory usage */
  91 /*#define DROPBEAR_BLOWFISH*/
  92 #define DROPBEAR_TWOFISH256
  93 #define DROPBEAR_TWOFISH128
  94
  95 /* Enable "Counter Mode" for ciphers. This is more secure than normal
  96  * CBC mode against certain attacks. This adds around 1kB to binary
  97  * size and is recommended for most cases */
  98 #define DROPBEAR_ENABLE_CTR_MODE
  99
 100 /* Message Integrity - at least one required.
 101  * Protocol RFC requires sha1 and recommends sha1-96.
 102  * sha1-96 may be of use for slow links, as it has a smaller overhead.
 103  *
 104  * Note: there's no point disabling sha1 to save space, since it's used
 105  * for the random number generator and public-key cryptography anyway.
 106  * Disabling it here will just stop it from being used as the integrity portion
 107  * of the ssh protocol.
 108  *
 109  * These hashes are also used for public key fingerprints in logs.
 110  * If you disable MD5, Dropbear will fall back to SHA1 fingerprints,
 111  * which are not the standard form. */
 112 #define DROPBEAR_SHA1_HMAC
 113 #define DROPBEAR_SHA1_96_HMAC
 114 #define DROPBEAR_MD5_HMAC
 115
 116 /* Hostkey/public key algorithms - at least one required, these are used
 117  * for hostkey as well as for verifying signatures with pubkey auth.
 118  * Removing either of these won't save very much space.
 119  * SSH2 RFC Draft requires dss, recommends rsa */
 120 #define DROPBEAR_RSA
 121 #define DROPBEAR_DSS
 122
 123 /* RSA can be vulnerable to timing attacks which use the time required for
 124  * signing to guess the private key. Blinding avoids this attack, though makes
 125  * signing operations slightly slower. */
 126 #define RSA_BLINDING
 127
 128 /* Define DSS_PROTOK to use PuTTY's method of generating the value k for dss,
 129  * rather than just from the random byte source. Undefining this will save you
 130  * ~4k in binary size with static uclibc, but your DSS hostkey could be exposed
 131  * if the random number source isn't good. In general this isn't required */
 132 /* #define DSS_PROTOK */
 133
 134 /* Control the memory/performance/compression tradeoff for zlib.
 135  * Set windowBits=8, memLevel=1 for least memory usage, see your system's
 136  * zlib.h for full details.
 137  * Default settings (windowBits=15, memLevel=8) will use
 138  * 256kB for compression + 32kB for decompression.
 139  * windowBits=8, memLevel=1 will use 10kB compression + 32kB decompression.
 140  * Note that windowBits is only set for deflate() - inflate() always uses the
 141  * default of 15 so as to interoperate with other clients. */
 142 #ifndef DROPBEAR_ZLIB_WINDOW_BITS
 143 #define DROPBEAR_ZLIB_WINDOW_BITS 15
 144 #endif
 145 #ifndef DROPBEAR_ZLIB_MEM_LEVEL
 146 #define DROPBEAR_ZLIB_MEM_LEVEL 8
 147 #endif
 148
 149 /* Whether to do reverse DNS lookups. */
 150 #define DO_HOST_LOOKUP
 151
 152 /* Whether to print the message of the day (MOTD). This doesn't add much code
 153  * size */
 154 #define DO_MOTD
 155
 156 /* The MOTD file path */
 157 #ifndef MOTD_FILENAME
 158 #define MOTD_FILENAME "/etc/motd"
 159 #endif
 160
 161 /* Authentication Types - at least one required.
 162    RFC Draft requires pubkey auth, and recommends password */
 163
 164 /* Note: PAM auth is quite simple, and only works for PAM modules which just do
 165  * a simple "Login: " "Password: " (you can edit the strings in svr-authpam.c).
 166  * It's useful for systems like OS X where standard password crypts don't work,
 167  * but there's an interface via a PAM module - don't bother using it otherwise.
 168  * You can't enable both PASSWORD and PAM. */
 169
 170 #define ENABLE_SVR_PASSWORD_AUTH
 171 /* PAM requires ./configure --enable-pam */
 172 /*#define ENABLE_SVR_PAM_AUTH*/
 173 #define ENABLE_SVR_PUBKEY_AUTH
 174
 175 /* Whether to take public key options in
 176  * authorized_keys file into account */
 177 #ifdef ENABLE_SVR_PUBKEY_AUTH
 178 #define ENABLE_SVR_PUBKEY_OPTIONS
 179 #endif
 180
 181 #define ENABLE_CLI_PASSWORD_AUTH
 182 #define ENABLE_CLI_PUBKEY_AUTH
 183 #define ENABLE_CLI_INTERACT_AUTH
 184
 185 /* This variable can be used to set a password for client
 186  * authentication on the commandline. Beware of platforms
 187  * that don't protect environment variables of processes etc. Also
 188  * note that it will be provided for all "hidden" client-interactive
 189  * style prompts - if you want something more sophisticated, use
 190  * SSH_ASKPASS instead. Comment out this var to remove this functionality.*/
 191 #define DROPBEAR_PASSWORD_ENV "DROPBEAR_PASSWORD"
 192
 193 /* Define this (as well as ENABLE_CLI_PASSWORD_AUTH) to allow the use of
 194  * a helper program for the ssh client. The helper program should be
 195  * specified in the SSH_ASKPASS environment variable, and dbclient
 196  * should be run with DISPLAY set and no tty. The program should
 197  * return the password on standard output */
 198 /*#define ENABLE_CLI_ASKPASS_HELPER*/
 199
 200 /* Random device to use - define either DROPBEAR_RANDOM_DEV or
 201  * DROPBEAR_PRNGD_SOCKET.
 202  * DROPBEAR_RANDOM_DEV is recommended on hosts with a good /dev/(u)random,
 203  * otherwise use run prngd (or egd if you want), specifying the socket.
 204  * The device will be queried for a few dozen bytes of seed a couple of times
 205  * per session (or more for very long-lived sessions). */
 206
 207 /* We'll use /dev/urandom by default, since /dev/random is too much hassle.
 208  * If system developers aren't keeping seeds between boots nor getting
 209  * any entropy from somewhere it's their own fault. */
 210 #define DROPBEAR_RANDOM_DEV "/dev/urandom"
 211
 212 /* prngd must be manually set up to produce output */
 213 /*#define DROPBEAR_PRNGD_SOCKET "/var/run/dropbear-rng"*/
 214
 215 /* Specify the number of clients we will allow to be connected but
 216  * not yet authenticated. After this limit, connections are rejected */
 217 /* The first setting is per-IP, to avoid denial of service */
 218 #ifndef MAX_UNAUTH_PER_IP
 219 #define MAX_UNAUTH_PER_IP 5
 220 #endif
 221
 222 /* And then a global limit to avoid chewing memory if connections
 223  * come from many IPs */
 224 #ifndef MAX_UNAUTH_CLIENTS
 225 #define MAX_UNAUTH_CLIENTS 30
 226 #endif
 227
 228 /* Maximum number of failed authentication tries (server option) */
 229 #ifndef MAX_AUTH_TRIES
 230 #define MAX_AUTH_TRIES 10
 231 #endif
 232
 233 /* The default file to store the daemon's process ID, for shutdown
 234    scripts etc. This can be overridden with the -P flag */
 235 #ifndef DROPBEAR_PIDFILE
 236 #define DROPBEAR_PIDFILE "/var/run/dropbear.pid"
 237 #endif
 238
 239 /* The command to invoke for xauth when using X11 forwarding.
 240  * "-q" for quiet */
 241 #ifndef XAUTH_COMMAND
 242 #define XAUTH_COMMAND "/usr/bin/X11/xauth -q"
 243 #endif
 244
 245 /* if you want to enable running an sftp server (such as the one included with
 246  * OpenSSH), set the path below. If the path isn't defined, sftp will not
 247  * be enabled */
 248 #ifndef SFTPSERVER_PATH
 249 #define SFTPSERVER_PATH "/usr/libexec/sftp-server"
 250 #endif
 251
 252 /* This is used by the scp binary when used as a client binary. If you're
 253  * not using the Dropbear client, you'll need to change it */
 254 #define _PATH_SSH_PROGRAM "/usr/bin/dbclient"
 255
 256 /* Whether to log commands executed by a client. This only logs the
 257  * (single) command sent to the server, not what a user did in a
 258  * shell/sftp session etc. */
 259 /* #define LOG_COMMANDS */
 260
 261 /* Window size limits. These tend to be a trade-off between memory
 262    usage and network performance: */
 263 /* Size of the network receive window. This amount of memory is allocated
 264    as a per-channel receive buffer. Increasing this value can make a
 265    significant difference to network performance. 24kB was empirically
 266    chosen for a 100mbit ethernet network. The value can be altered at
 267    runtime with the -W argument. */
 268 #ifndef DEFAULT_RECV_WINDOW
 269 #define DEFAULT_RECV_WINDOW 24576
 270 #endif
 271 /* Maximum size of a received SSH data packet - this _MUST_ be >= 32768
 272    in order to interoperate with other implementations */
 273 #ifndef RECV_MAX_PAYLOAD_LEN
 274 #define RECV_MAX_PAYLOAD_LEN 32768
 275 #endif
 276 /* Maximum size of a transmitted data packet - this can be any value,
 277    though increasing it may not make a significant difference. */
 278 #ifndef TRANS_MAX_PAYLOAD_LEN
 279 #define TRANS_MAX_PAYLOAD_LEN 16384
 280 #endif
 281
 282 /* Ensure that data is transmitted every KEEPALIVE seconds. This can
 283 be overridden at runtime with -K. 0 disables keepalives */
 284 #define DEFAULT_KEEPALIVE 0
 285
 286 /* Ensure that data is received within IDLE_TIMEOUT seconds. This can
 287 be overridden at runtime with -I. 0 disables idle timeouts */
 288 #define DEFAULT_IDLE_TIMEOUT 0
 289
 290 /* The default path. This will often get replaced by the shell */
 291 #define DEFAULT_PATH "/usr/bin:/bin"
 292
 293 /* Some other defines (that mostly should be left alone) are defined
 294  * in sysoptions.h */
 295 #include "sysoptions.h"
 296
 297 #endif /* _OPTIONS_H_ */