--- a/default_options.h	Wed Feb 21 21:59:52 2018 +0800
+++ b/default_options.h	Mon Feb 26 22:44:48 2018 +0800
@@ -1,44 +1,27 @@
-/*
- > > > Do not edit this file (default_options.h) < < <
-Generated from ../default_options.h.in
-Local customisation goes in localoptions.h
-*/
-
-
 #ifndef DROPBEAR_DEFAULT_OPTIONS_H_
 #define DROPBEAR_DEFAULT_OPTIONS_H_
 /*
                      > > > Read This < < <
 
-default_options.h.in  documents compile-time options, and provides default values.
+default_options.h  documents compile-time options, and provides default values.
 
 Local customisation should be added to localoptions.h which is
 used if it exists. Options defined there will override any options in this
 file.
 
-Options can also be defined with -DDROPBEAR_XXX in Makefile CFLAGS
-
-IMPORTANT: Many options will require "make clean" after changes */
+Options can also be defined with -DDROPBEAR_XXX=[0,1] in Makefile CFLAGS
 
-#ifndef DROPBEAR_DEFPORT
+IMPORTANT: Some options will require "make clean" after changes */
+
 #define DROPBEAR_DEFPORT "22"
-#endif
 
 /* Listen on all interfaces */
-#ifndef DROPBEAR_DEFADDRESS
 #define DROPBEAR_DEFADDRESS ""
-#endif
 
 /* Default hostkey paths - these can be specified on the command line */
-#ifndef DSS_PRIV_FILENAME
 #define DSS_PRIV_FILENAME "/etc/dropbear/dropbear_dss_host_key"
-#endif
-#ifndef RSA_PRIV_FILENAME
 #define RSA_PRIV_FILENAME "/etc/dropbear/dropbear_rsa_host_key"
-#endif
-#ifndef ECDSA_PRIV_FILENAME
 #define ECDSA_PRIV_FILENAME "/etc/dropbear/dropbear_ecdsa_host_key"
-#endif
 
 /* Set NON_INETD_MODE if you require daemon functionality (ie Dropbear listens
  * on chosen ports and keeps accepting connections. This is the default.
@@ -50,140 +33,76 @@
  *
  * Both of these flags can be defined at once, don't compile without at least
  * one of them. */
-#ifndef NON_INETD_MODE
 #define NON_INETD_MODE 1
-#endif
-#ifndef INETD_MODE
 #define INETD_MODE 1
-#endif
 
-/* 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*/
+/* Include verbose debug output, enabled with -v at runtime. 
+ * This will add a reasonable amount to your executable size. */
+#define DEBUG_TRACE 0
 
 /* 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. */
-#ifndef DROPBEAR_SMALL_CODE
+ * 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. */
 #define DROPBEAR_SMALL_CODE 1
-#endif
 
 /* Enable X11 Forwarding - server only */
-#ifndef DROPBEAR_X11FWD
 #define DROPBEAR_X11FWD 1
-#endif
 
 /* Enable TCP Fowarding */
 /* 'Local' is "-L" style (client listening port forwarded via server)
  * 'Remote' is "-R" style (server listening port forwarded via client) */
-
-#ifndef DROPBEAR_CLI_LOCALTCPFWD
 #define DROPBEAR_CLI_LOCALTCPFWD 1
-#endif
-#ifndef DROPBEAR_CLI_REMOTETCPFWD
 #define DROPBEAR_CLI_REMOTETCPFWD 1
-#endif
 
-#ifndef DROPBEAR_SVR_LOCALTCPFWD
 #define DROPBEAR_SVR_LOCALTCPFWD 1
-#endif
-#ifndef DROPBEAR_SVR_REMOTETCPFWD
 #define DROPBEAR_SVR_REMOTETCPFWD 1
-#endif
 
 /* Enable Authentication Agent Forwarding */
-#ifndef DROPBEAR_SVR_AGENTFWD
 #define DROPBEAR_SVR_AGENTFWD 1
-#endif
-#ifndef DROPBEAR_CLI_AGENTFWD
 #define DROPBEAR_CLI_AGENTFWD 1
-#endif
-
 
 /* Note: Both DROPBEAR_CLI_PROXYCMD and DROPBEAR_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 */
-#ifndef DROPBEAR_CLI_PROXYCMD
 #define DROPBEAR_CLI_PROXYCMD 1
-#endif
 
 /* Enable "Netcat mode" option. This will forward standard input/output
  * to a remote TCP-forwarded connection */
-#ifndef DROPBEAR_CLI_NETCAT
 #define DROPBEAR_CLI_NETCAT 1
-#endif
 
 /* Whether to support "-c" and "-m" flags to choose ciphers/MACs at runtime */
-#ifndef ENABLE_USER_ALGO_LIST
-#define ENABLE_USER_ALGO_LIST 1
-#endif
+#define DROPBEAR_USER_ALGO_LIST 1
 
 /* 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.*/
-#ifndef DROPBEAR_AES128
+ * AES128 should be enabled, some very old implementations might only
+ * support 3DES.
+ * Including both AES keysize variants (128 and 256) will result in 
+ * a minimal size increase */
 #define DROPBEAR_AES128 1
-#endif
-#ifndef DROPBEAR_3DES
 #define DROPBEAR_3DES 1
-#endif
-#ifndef DROPBEAR_AES256
 #define DROPBEAR_AES256 1
-#endif
+#define DROPBEAR_TWOFISH256 0
+#define DROPBEAR_TWOFISH128 0
 /* Compiling in Blowfish will add ~6kB to runtime heap memory usage */
-/*#define DROPBEAR_BLOWFISH*/
-#ifndef DROPBEAR_TWOFISH256
-#define DROPBEAR_TWOFISH256 1
-#endif
-#ifndef DROPBEAR_TWOFISH128
-#define DROPBEAR_TWOFISH128 1
-#endif
+#define DROPBEAR_BLOWFISH 0
 
 /* Enable CBC mode for ciphers. This has security issues though
  * is the most compatible with older SSH implementations */
-#ifndef DROPBEAR_ENABLE_CBC_MODE
 #define DROPBEAR_ENABLE_CBC_MODE 1
-#endif
 
-/* Enable "Counter Mode" for ciphers. This is more secure than normal
+/* Enable "Counter Mode" for ciphers. This is more secure than
  * CBC mode against certain attacks. It is recommended for security
  * and forwards compatibility */
-#ifndef DROPBEAR_ENABLE_CTR_MODE
 #define DROPBEAR_ENABLE_CTR_MODE 1
-#endif
-
-/* Twofish counter mode is disabled by default because it 
-has not been tested for interoperability with other SSH implementations.
-If you test it please contact the Dropbear author */
-#ifndef DROPBEAR_TWOFISH_CTR
-#define DROPBEAR_TWOFISH_CTR 0
-#endif
 
 /* Message integrity. sha2-256 is recommended as a default, 
    sha1 for compatibility */
-#ifndef DROPBEAR_SHA1_HMAC
 #define DROPBEAR_SHA1_HMAC 1
-#endif
-#ifndef DROPBEAR_SHA1_96_HMAC
 #define DROPBEAR_SHA1_96_HMAC 1
-#endif
-#ifndef DROPBEAR_SHA2_256_HMAC
 #define DROPBEAR_SHA2_256_HMAC 1
-#endif
-/* Default is to include it is sha512 is being compiled in for ECDSA */
-#ifndef DROPBEAR_SHA2_512_HMAC
-#define DROPBEAR_SHA2_512_HMAC (DROPBEAR_ECDSA)
-#endif
-
-/* XXX needed for fingerprints */
-#ifndef DROPBEAR_MD5_HMAC
-#define DROPBEAR_MD5_HMAC 0
-#endif
 
 /* Hostkey/public key algorithms - at least one required, these are used
  * for hostkey as well as for verifying signatures with pubkey auth.
@@ -191,23 +110,15 @@
  * RSA is recommended
  * DSS may be necessary to connect to some systems though
    is not recommended for new keys */
-#ifndef DROPBEAR_RSA
 #define DROPBEAR_RSA 1
-#endif
-#ifndef DROPBEAR_DSS
 #define DROPBEAR_DSS 1
-#endif
 /* ECDSA is significantly faster than RSA or DSS. Compiling in ECC
  * code (either ECDSA or ECDH) increases binary size - around 30kB
  * on x86-64 */
-#ifndef DROPBEAR_ECDSA
 #define DROPBEAR_ECDSA 1
-#endif
 
 /* RSA must be >=1024 */
-#ifndef DROPBEAR_DEFAULT_RSA_SIZE
 #define DROPBEAR_DEFAULT_RSA_SIZE 2048
-#endif
 /* DSS is always 1024 */
 /* ECDSA defaults to largest size configured, usually 521 */
 
@@ -215,46 +126,40 @@
    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. */
-#ifndef DROPBEAR_DELAY_HOSTKEY
 #define DROPBEAR_DELAY_HOSTKEY 1
-#endif
 
-/* Enable Curve25519 for key exchange. This is another elliptic
- * curve method with good security properties. Increases binary size
- * by ~8kB on x86-64 */
-#ifndef DROPBEAR_CURVE25519
-#define DROPBEAR_CURVE25519 1
-#endif
-
-/* Enable elliptic curve Diffie Hellman key exchange, see note about
- * ECDSA above */
-#ifndef DROPBEAR_ECDH
-#define DROPBEAR_ECDH 1
-#endif
 
 /* Key exchange algorithm.
+
  * group14_sha1 - 2048 bit, sha1
  * group14_sha256 - 2048 bit, sha2-256
  * group16 - 4096 bit, sha2-512
  * group1 - 1024 bit, sha1
+ * curve25519 - elliptic curve DH
+ * ecdh - NIST elliptic curve DH (256, 384, 521)
  *
- * group14 is supported by most implementations.
- * group16 provides a greater strength level but is slower and increases binary size
  * group1 is too small for security though is necessary if you need 
      compatibility with some implementations such as Dropbear versions < 0.53
+ * group14 is supported by most implementations.
+ * group16 provides a greater strength level but is slower and increases binary size
+ * curve25519 and ecdh algorithms are faster than non-elliptic curve methods
+ * curve25519 increases binary size by ~8kB on x86-64
+ * including either ECDH or ECDSA increases binary size by ~30kB on x86-64
+
+ * Small systems should generally include either curve25519 or ecdh for performance.
+ * curve25519 is less widely supported but is faster
  */ 
-#ifndef DROPBEAR_DH_GROUP1
-#define DROPBEAR_DH_GROUP1 1
-#endif
-#ifndef DROPBEAR_DH_GROUP14_SHA1
 #define DROPBEAR_DH_GROUP14_SHA1 1
-#endif
-#ifndef DROPBEAR_DH_GROUP14_SHA256
 #define DROPBEAR_DH_GROUP14_SHA256 1
-#endif
-#ifndef DROPBEAR_DH_GROUP16
 #define DROPBEAR_DH_GROUP16 0
-#endif
+#define DROPBEAR_CURVE25519 1
+#define DROPBEAR_ECDH 1
+#define DROPBEAR_DH_GROUP1 1
+
+/* When group1 is enabled it will only be allowed by Dropbear client
+not as a server, due to concerns over its strength. Set to 0 to allow
+group1 in Dropbear server too */
+#define DROPBEAR_DH_GROUP1_CLIENTONLY 1
 
 /* Control the memory/performance/compression tradeoff for zlib.
  * Set windowBits=8 for least memory usage, see your system's
@@ -263,27 +168,18 @@
  * windowBits=8 will use 129kB for compression.
  * Both modes will use ~35kB for decompression (using windowBits=15 for
  * interoperability) */
-#ifndef DROPBEAR_ZLIB_WINDOW_BITS
 #define DROPBEAR_ZLIB_WINDOW_BITS 15 
-#endif
 
 /* Whether to do reverse DNS lookups. */
-#ifndef DO_HOST_LOOKUP
 #define DO_HOST_LOOKUP 0
-#endif
 
 /* Whether to print the message of the day (MOTD). */
-#ifndef DO_MOTD
 #define DO_MOTD 0
-#endif
-
-/* The MOTD file path */
-#ifndef MOTD_FILENAME
 #define MOTD_FILENAME "/etc/motd"
-#endif
 
 /* Authentication Types - at least one required.
    RFC Draft requires pubkey auth, and recommends password */
+#define DROPBEAR_SVR_PASSWORD_AUTH 1
 
 /* 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).
@@ -291,138 +187,79 @@
  * 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. */
+#define DROPBEAR_SVR_PAM_AUTH 0
 
-/* This requires crypt() */
-#ifdef HAVE_CRYPT
-#ifndef DROPBEAR_SVR_PASSWORD_AUTH
-#define DROPBEAR_SVR_PASSWORD_AUTH 1
-#endif
-#else
-#ifndef DROPBEAR_SVR_PASSWORD_AUTH
-#define DROPBEAR_SVR_PASSWORD_AUTH 0
-#endif
-#endif
-/* PAM requires ./configure --enable-pam */
-#ifndef DROPBEAR_SVR_PAM_AUTH
-#define DROPBEAR_SVR_PAM_AUTH 0
-#endif
-#ifndef DROPBEAR_SVR_PUBKEY_AUTH
+/* ~/.ssh/authorized_keys authentication */
 #define DROPBEAR_SVR_PUBKEY_AUTH 1
-#endif
 
 /* Whether to take public key options in 
  * authorized_keys file into account */
-#ifndef DROPBEAR_SVR_PUBKEY_OPTIONS
 #define DROPBEAR_SVR_PUBKEY_OPTIONS 1
-#endif
 
-/* This requires getpass. */
-#ifdef HAVE_GETPASS
-#ifndef DROPBEAR_CLI_PASSWORD_AUTH
+/* Client authentication options */
 #define DROPBEAR_CLI_PASSWORD_AUTH 1
-#endif
-#ifndef DROPBEAR_CLI_INTERACT_AUTH
-#define DROPBEAR_CLI_INTERACT_AUTH 1
-#endif
-#endif
-#ifndef DROPBEAR_CLI_PUBKEY_AUTH
 #define DROPBEAR_CLI_PUBKEY_AUTH 1
-#endif
 
 /* A default argument for dbclient -i <privatekey>. 
 Homedir is prepended unless path begins with / */
-#ifndef DROPBEAR_DEFAULT_CLI_AUTHKEY
 #define DROPBEAR_DEFAULT_CLI_AUTHKEY ".ssh/id_dropbear"
-#endif
 
-/* 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.*/
-#ifndef DROPBEAR_PASSWORD_ENV
-#define DROPBEAR_PASSWORD_ENV "DROPBEAR_PASSWORD"
-#endif
+/* Allow specifying the password for dbclient via the DROPBEAR_PASSWORD
+ * environment variable. */
+#define DROPBEAR_USE_PASSWORD_ENV 1
 
 /* Define this (as well as DROPBEAR_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 */
-#ifndef DROPBEAR_CLI_ASKPASS_HELPER
 #define DROPBEAR_CLI_ASKPASS_HELPER 0
-#endif
 
 /* 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 */
-#ifndef DROPBEAR_CLI_IMMEDIATE_AUTH
+ * sending a query for the available methods. This is not yet enabled by default 
+ since it could cause problems with non-compliant servers */ 
 #define DROPBEAR_CLI_IMMEDIATE_AUTH 0
-#endif
 
-/* 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 */
-#ifndef DROPBEAR_URANDOM_DEV
-#define DROPBEAR_URANDOM_DEV "/dev/urandom"
-#endif
-
-/* Set this to use PRNGD or EGD instead of /dev/urandom or /dev/random */
-/*#define DROPBEAR_PRNGD_SOCKET "/var/run/dropbear-rng"*/
-
+/* Set this to use PRNGD or EGD instead of /dev/urandom */
+#define DROPBEAR_USE_PRNGD 0
+#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 */
-#ifndef MAX_UNAUTH_PER_IP
 #define MAX_UNAUTH_PER_IP 5
-#endif
 
 /* And then a global limit to avoid chewing memory if connections 
  * come from many IPs */
-#ifndef MAX_UNAUTH_CLIENTS
 #define MAX_UNAUTH_CLIENTS 30
-#endif
 
 /* Default maximum number of failed authentication tries (server option) */
 /* -T server option overrides */
-#ifndef MAX_AUTH_TRIES
 #define MAX_AUTH_TRIES 10
-#endif
 
 /* The default file to store the daemon's process ID, for shutdown
    scripts etc. This can be overridden with the -P flag */
-#ifndef DROPBEAR_PIDFILE
 #define DROPBEAR_PIDFILE "/var/run/dropbear.pid"
-#endif
 
 /* The command to invoke for xauth when using X11 forwarding.
  * "-q" for quiet */
-#ifndef XAUTH_COMMAND
 #define XAUTH_COMMAND "/usr/bin/xauth -q"
-#endif
+
 
 /* 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 */
-#ifndef SFTPSERVER_PATH
+ * OpenSSH), set the path below and set DROPBEAR_SFTPSERVER. 
+ * The sftp-server program is not provided by Dropbear itself */
+#define DROPBEAR_SFTPSERVER 1
 #define SFTPSERVER_PATH "/usr/libexec/sftp-server"
-#endif
 
 /* 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 */
-#ifndef DROPBEAR_PATH_SSH_PROGRAM
 #define DROPBEAR_PATH_SSH_PROGRAM "/usr/bin/dbclient"
-#endif
 
 /* 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. */
-#ifndef LOG_COMMANDS
 #define LOG_COMMANDS 0
-#endif
 
 /* Window size limits. These tend to be a trade-off between memory
    usage and network performance: */
@@ -431,42 +268,28 @@
    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. */
-#ifndef DEFAULT_RECV_WINDOW
 #define DEFAULT_RECV_WINDOW 24576
-#endif
 /* Maximum size of a received SSH data packet - this _MUST_ be >= 32768
    in order to interoperate with other implementations */
-#ifndef RECV_MAX_PAYLOAD_LEN
 #define RECV_MAX_PAYLOAD_LEN 32768
-#endif
 /* Maximum size of a transmitted data packet - this can be any value,
    though increasing it may not make a significant difference. */
-#ifndef TRANS_MAX_PAYLOAD_LEN
 #define TRANS_MAX_PAYLOAD_LEN 16384
-#endif
 
 /* Ensure that data is transmitted every KEEPALIVE seconds. This can
 be overridden at runtime with -K. 0 disables keepalives */
-#ifndef DEFAULT_KEEPALIVE
 #define DEFAULT_KEEPALIVE 0
-#endif
 
 /* 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 */
-#ifndef DEFAULT_KEEPALIVE_LIMIT
 #define DEFAULT_KEEPALIVE_LIMIT 3
-#endif
 
 /* Ensure that data is received within IDLE_TIMEOUT seconds. This can
 be overridden at runtime with -I. 0 disables idle timeouts */
-#ifndef DEFAULT_IDLE_TIMEOUT
 #define DEFAULT_IDLE_TIMEOUT 0
-#endif
 
 /* The default path. This will often get replaced by the shell */
-#ifndef DEFAULT_PATH
 #define DEFAULT_PATH "/usr/bin:/bin"
-#endif
 
 #endif /* DROPBEAR_DEFAULT_OPTIONS_H_ */