diff options
authorP. J. McDermott <>2014-10-18 11:05:27 (EDT)
committer P. J. McDermott <>2014-10-18 11:05:27 (EDT)
commitdbc07228ea7ae8ead241d526876114ab21e7dcee (patch)
parent817f60612b35d5b07b6bdfec9bc86ebae36532e4 (diff)
options.h: New file
1 files changed, 327 insertions, 0 deletions
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+/* Dropbear SSH
+ * Copyright (c) 2002,2003 Matt Johnston
+ * All rights reserved. See LICENSE for the license. */
+#ifndef _OPTIONS_H_
+#define _OPTIONS_H_
+/* Define compile-time options below - the "#ifndef DROPBEAR_XXX .... #endif"
+ * parts are to allow for commandline -DDROPBEAR_XXX options etc. */
+/* IMPORTANT: Many options will require "make clean" after changes */
+#define DROPBEAR_DEFPORT "22"
+/* Listen on all interfaces */
+/* Default hostkey paths - these can be specified on the command line */
+#define DSS_PRIV_FILENAME "/etc/dropbear/dropbear_dss_host_key"
+#define RSA_PRIV_FILENAME "/etc/dropbear/dropbear_rsa_host_key"
+#define ECDSA_PRIV_FILENAME "/etc/dropbear/dropbear_ecdsa_host_key"
+/* Set NON_INETD_MODE if you require daemon functionality (ie Dropbear listens
+ * on chosen ports and keeps accepting connections. This is the default.
+ *
+ * Set INETD_MODE if you want to be able to run Dropbear with inetd (or
+ * similar), where it will use stdin/stdout for connections, and each process
+ * lasts for a single connection. Dropbear should be invoked with the -i flag
+ * for inetd, and can only accept IPv4 connections.
+ *
+ * Both of these flags can be defined at once, don't compile without at least
+ * one of them. */
+/*#define INETD_MODE*/
+/* Setting this disables the fast exptmod bignum code. It saves ~5kB, but is
+ * perhaps 20% slower for pubkey operations (it is probably worth experimenting
+ * if you want to use this) */
+/*#define NO_FAST_EXPTMOD*/
+/* Set this if you want to use the DROPBEAR_SMALL_CODE option. This can save
+several kB in binary size however will make the symmetrical ciphers and hashes
+slower, perhaps by 50%. Recommended for small systems that aren't doing
+much traffic. */
+/* Enable X11 Forwarding - server only */
+/*#define ENABLE_X11FWD*/
+/* Enable TCP Fowarding */
+/* 'Local' is "-L" style (client listening port forwarded via server)
+ * 'Remote' is "-R" style (server listening port forwarded via client) */
+/* Enable Authentication Agent Forwarding */
+/* Note: Both ENABLE_CLI_PROXYCMD and ENABLE_CLI_NETCAT must be set to
+ * allow multihop dbclient connections */
+/* Allow using -J <proxycommand> to run the connection through a
+ pipe to a program, rather the normal TCP connection */
+/* Enable "Netcat mode" option. This will forward standard input/output
+ * to a remote TCP-forwarded connection */
+/*#define ENABLE_CLI_NETCAT*/
+/* Whether to support "-c" and "-m" flags to choose ciphers/MACs at runtime */
+/* Encryption - at least one required.
+ * Protocol RFC requires 3DES and recommends AES128 for interoperability.
+ * Including multiple keysize variants the same cipher
+ * (eg AES256 as well as AES128) will result in a minimal size increase.*/
+#define DROPBEAR_AES128
+#define DROPBEAR_3DES
+#define DROPBEAR_AES256
+/* Compiling in Blowfish will add ~6kB to runtime heap memory usage */
+/*#define DROPBEAR_TWOFISH256*/
+/*#define DROPBEAR_TWOFISH128*/
+/* Enable "Counter Mode" for ciphers. This is more secure than normal
+ * CBC mode against certain attacks. This adds around 1kB to binary
+ * size and is recommended for most cases */
+/* You can compile with no encryption if you want. In some circumstances
+ * this could be safe security-wise, though make sure you know what
+ * you're doing. Anyone can see everything that goes over the wire, so
+ * the only safe auth method is public key. */
+/* Message Integrity - at least one required.
+ * Protocol RFC requires sha1 and recommends sha1-96.
+ * sha1-96 is of use for slow links as it has a smaller overhead.
+ *
+ * There's no reason to disable sha1 or sha1-96 to save space since it's
+ * used for the random number generator and public-key cryptography anyway.
+ * Disabling it here will just stop it from being used as the integrity portion
+ * of the ssh protocol.
+ *
+ * These hashes are also used for public key fingerprints in logs.
+ * If you disable MD5, Dropbear will fall back to SHA1 fingerprints,
+ * which are not the standard form. */
+#define DROPBEAR_SHA1_96_HMAC
+/*#define DROPBEAR_SHA2_256_HMAC*/
+/*#define DROPBEAR_SHA2_512_HMAC*/
+/* You can also disable integrity. Don't bother disabling this if you're
+ * still using a cipher, it's relatively cheap. If you disable this it's dead
+ * simple for an attacker to run arbitrary commands on the remote host. Beware. */
+/* Hostkey/public key algorithms - at least one required, these are used
+ * for hostkey as well as for verifying signatures with pubkey auth.
+ * Removing either of these won't save very much space.
+ * SSH2 RFC Draft requires dss, recommends rsa */
+/* ECDSA is significantly faster than RSA or DSS. Compiling in ECC
+ * code (either ECDSA or ECDH) increases binary size - around 30kB
+ * on x86-64 */
+/* Generate hostkeys as-needed when the first connection using that key type occurs.
+ This avoids the need to otherwise run "dropbearkey" and avoids some problems
+ with badly seeded /dev/urandom when systems first boot.
+ This also requires a runtime flag "-R". This adds ~4kB to binary size (or hardly
+ anything if dropbearkey is linked in a "dropbearmulti" binary) */
+/* Enable Curve25519 for key exchange. This is another elliptic
+ * curve method with good security properties. Increases binary size
+ * by ~8kB on x86-64 */
+#define DROPBEAR_CURVE25519
+/* Enable elliptic curve Diffie Hellman key exchange, see note about
+ * ECDSA above */
+/* Control the memory/performance/compression tradeoff for zlib.
+ * Set windowBits=8 for least memory usage, see your system's
+ * zlib.h for full details.
+ * Default settings (windowBits=15) will use 256kB for compression
+ * windowBits=8 will use 129kB for compression.
+ * Both modes will use ~35kB for decompression (using windowBits=15 for
+ * interoperability) */
+/* Whether to do reverse DNS lookups. */
+/*#define DO_HOST_LOOKUP */
+/* Whether to print the message of the day (MOTD). This doesn't add much code
+ * size */
+#define DO_MOTD
+/* The MOTD file path */
+#define MOTD_FILENAME "/etc/motd"
+/* Authentication Types - at least one required.
+ RFC Draft requires pubkey auth, and recommends password */
+/* Note: PAM auth is quite simple and only works for PAM modules which just do
+ * a simple "Login: " "Password: " (you can edit the strings in svr-authpam.c).
+ * It's useful for systems like OS X where standard password crypts don't work
+ * but there's an interface via a PAM module. It won't work for more complex
+ * PAM challenge/response.
+ * You can't enable both PASSWORD and PAM. */
+/* PAM requires ./configure --enable-pam */
+/*#define ENABLE_SVR_PAM_AUTH */
+/* Whether to take public key options in
+ * authorized_keys file into account */
+/* This variable can be used to set a password for client
+ * authentication on the commandline. Beware of platforms
+ * that don't protect environment variables of processes etc. Also
+ * note that it will be provided for all "hidden" client-interactive
+ * style prompts - if you want something more sophisticated, use
+ * SSH_ASKPASS instead. Comment out this var to remove this functionality.*/
+/* Define this (as well as ENABLE_CLI_PASSWORD_AUTH) to allow the use of
+ * a helper program for the ssh client. The helper program should be
+ * specified in the SSH_ASKPASS environment variable, and dbclient
+ * should be run with DISPLAY set and no tty. The program should
+ * return the password on standard output */
+/* Save a network roundtrip by sendng a real auth request immediately after
+ * sending a query for the available methods. It is at the expense of < 100
+ * bytes of extra network traffic. This is not yet enabled by default since it
+ * could cause problems with non-compliant servers */
+/* Source for randomness. This must be able to provide hundreds of bytes per SSH
+ * connection without blocking. In addition /dev/random is used for seeding
+ * rsa/dss key generation */
+#define DROPBEAR_URANDOM_DEV "/dev/urandom"
+/* Set this to use PRNGD or EGD instead of /dev/urandom or /dev/random */
+/*#define DROPBEAR_PRNGD_SOCKET "/var/run/dropbear-rng"*/
+/* Specify the number of clients we will allow to be connected but
+ * not yet authenticated. After this limit, connections are rejected */
+/* The first setting is per-IP, to avoid denial of service */
+#define MAX_UNAUTH_PER_IP 5
+/* And then a global limit to avoid chewing memory if connections
+ * come from many IPs */
+/* Maximum number of failed authentication tries (server option) */
+#define MAX_AUTH_TRIES 10
+/* The default file to store the daemon's process ID, for shutdown
+ scripts etc. This can be overridden with the -P flag */
+#define DROPBEAR_PIDFILE "/var/run/"
+/* The command to invoke for xauth when using X11 forwarding.
+ * "-q" for quiet */
+/*#define XAUTH_COMMAND "/usr/bin/xauth -q"*/
+/* if you want to enable running an sftp server (such as the one included with
+ * OpenSSH), set the path below. If the path isn't defined, sftp will not
+ * be enabled */
+/*#define SFTPSERVER_PATH "/usr/libexec/sftp-server"*/
+/* This is used by the scp binary when used as a client binary. If you're
+ * not using the Dropbear client, you'll need to change it */
+#define _PATH_SSH_PROGRAM "/usr/bin/dbclient"
+/* Whether to log commands executed by a client. This only logs the
+ * (single) command sent to the server, not what a user did in a
+ * shell/sftp session etc. */
+/* #define LOG_COMMANDS */
+/* Window size limits. These tend to be a trade-off between memory
+ usage and network performance: */
+/* Size of the network receive window. This amount of memory is allocated
+ as a per-channel receive buffer. Increasing this value can make a
+ significant difference to network performance. 24kB was empirically
+ chosen for a 100mbit ethernet network. The value can be altered at
+ runtime with the -W argument. */
+#define DEFAULT_RECV_WINDOW 24576
+/* Maximum size of a received SSH data packet - this _MUST_ be >= 32768
+ in order to interoperate with other implementations */
+#define RECV_MAX_PAYLOAD_LEN 32768
+/* Maximum size of a transmitted data packet - this can be any value,
+ though increasing it may not make a significant difference. */
+#define TRANS_MAX_PAYLOAD_LEN 16384
+/* Ensure that data is transmitted every KEEPALIVE seconds. This can
+be overridden at runtime with -K. 0 disables keepalives */
+/* If this many KEEPALIVES are sent with no packets received from the
+other side, exit. Not run-time configurable - if you have a need
+for runtime configuration please mail the Dropbear list */
+/* Ensure that data is received within IDLE_TIMEOUT seconds. This can
+be overridden at runtime with -I. 0 disables idle timeouts */
+/* The default path. This will often get replaced by the shell */
+#define DEFAULT_PATH "/usr/bin:/bin"
+/* Some other defines (that mostly should be left alone) are defined
+ * in sysoptions.h */
+#include "sysoptions.h"
+#endif /* _OPTIONS_H_ */