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Diffstat (limited to 'src/default_options.h')
| -rw-r--r-- | src/default_options.h | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/src/default_options.h b/src/default_options.h new file mode 100644 index 0000000..5132775 --- /dev/null +++ b/src/default_options.h @@ -0,0 +1,357 @@ +#ifndef DROPBEAR_DEFAULT_OPTIONS_H_ +#define DROPBEAR_DEFAULT_OPTIONS_H_ +/* + > > > Read This < < < + +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 in the build directory. Options defined there will override +any options in this file. + +Options can also be defined with -DDROPBEAR_XXX=[0,1] in Makefile CFLAGS + +IMPORTANT: Some options will require "make clean" after changes */ + +#define DROPBEAR_DEFPORT "22" + +/* Listen on all interfaces */ +#define DROPBEAR_DEFADDRESS "" + +/* Default hostkey paths - these can be specified on the command line. + * Homedir is prepended if path begins with ~/ + */ +#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" +#define ED25519_PRIV_FILENAME "/etc/dropbear/dropbear_ed25519_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 NON_INETD_MODE 1 +#define INETD_MODE 1 + +/* By default Dropbear will re-execute itself for each incoming connection so + that memory layout may be re-randomised (ASLR) - exploiting + vulnerabilities becomes harder. Re-exec causes slightly more memory use + per connection. + This option is ignored on non-Linux platforms at present */ +#define DROPBEAR_REEXEC 1 + +/* Include verbose debug output, enabled with -v at runtime (repeat to increase). + * define which level of debug output you compile in + * TRACE1 - TRACE3 = approx 4 Kb (connection, remote identity, algos, auth type info) + * TRACE4 = approx 17 Kb (detailed before connection) + * TRACE5 = approx 8 Kb (detailed after connection) */ +#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. */ +#define DROPBEAR_SMALL_CODE 1 + +/* Enable X11 Forwarding - server only */ +#define DROPBEAR_X11FWD 0 + +/* Enable TCP Fowarding */ +/* 'Local' is "-L" style (client listening port forwarded via server) + * 'Remote' is "-R" style (server listening port forwarded via client) */ +#define DROPBEAR_CLI_LOCALTCPFWD 1 +#define DROPBEAR_CLI_REMOTETCPFWD 1 + +#define DROPBEAR_SVR_LOCALTCPFWD 1 +#define DROPBEAR_SVR_REMOTETCPFWD 1 + +/* Enable Authentication Agent Forwarding */ +#define DROPBEAR_SVR_AGENTFWD 1 +#define DROPBEAR_CLI_AGENTFWD 1 + +/* 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 */ +#define DROPBEAR_CLI_PROXYCMD 1 + +/* Enable "Netcat mode" option. This will forward standard input/output + * to a remote TCP-forwarded connection */ +#define DROPBEAR_CLI_NETCAT 1 + +/* Whether to support "-c" and "-m" flags to choose ciphers/MACs at runtime */ +#define DROPBEAR_USER_ALGO_LIST 1 + +/* Encryption - at least one required. + * 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 +#define DROPBEAR_AES256 1 +#define DROPBEAR_3DES 0 + +/* Enable Chacha20-Poly1305 authenticated encryption mode. This is + * generally faster than AES256 on CPU w/o dedicated AES instructions, + * having the same key size. Recommended. + * Compiling in will add ~5,5kB to binary size on x86-64 */ +#define DROPBEAR_CHACHA20POLY1305 1 + +/* Enable "Counter Mode" for ciphers. Recommended. */ +#define DROPBEAR_ENABLE_CTR_MODE 1 + +/* Enable CBC mode for ciphers. This has security issues though + may be required for compatibility with old implementations */ +#define DROPBEAR_ENABLE_CBC_MODE 0 + +/* Enable "Galois/Counter Mode" for ciphers. This authenticated + * encryption mode is combination of CTR mode and GHASH. Recommended + * for security and forwards compatibility, but slower than CTR on + * CPU w/o dedicated AES/GHASH instructions. + * Compiling in will add ~6kB to binary size on x86-64 */ +#define DROPBEAR_ENABLE_GCM_MODE 0 + +/* Message integrity. sha2-256 is recommended as a default, + sha1 for compatibility */ +#define DROPBEAR_SHA1_HMAC 1 +#define DROPBEAR_SHA2_256_HMAC 1 +#define DROPBEAR_SHA2_512_HMAC 0 +#define DROPBEAR_SHA1_96_HMAC 0 + +/* Hostkey/public key algorithms - at least one required, these are used + * for hostkey as well as for verifying signatures with pubkey auth. + * RSA is recommended. + * + * See: RSA_PRIV_FILENAME and DSS_PRIV_FILENAME */ +#define DROPBEAR_RSA 1 +/* Newer SSH implementations use SHA256 for RSA signatures. SHA1 + * support is required to communicate with some older implementations. + * It will be removed in future due to SHA1 insecurity, it can be + * disabled with DROPBEAR_RSA_SHA1 set to 0 */ +#define DROPBEAR_RSA_SHA1 1 + +/* DSS may be necessary to connect to some systems but is not + * recommended for new keys (1024 bits is small, and it uses SHA1). + * RSA key generation will be faster with bundled libtommath + * if DROPBEAR_DSS is disabled. + * https://github.com/mkj/dropbear/issues/174#issuecomment-1267374858 */ +#define DROPBEAR_DSS 0 +/* ECDSA is significantly faster than RSA or DSS. Compiling in ECC + * code (either ECDSA or ECDH) increases binary size - around 30kB + * on x86-64. + * See: ECDSA_PRIV_FILENAME */ +#define DROPBEAR_ECDSA 1 + +/* Ed25519 is faster than ECDSA. Compiling in Ed25519 code increases + * binary size - around 7,5kB on x86-64. + * See: ED25519_PRIV_FILENAME */ +#define DROPBEAR_ED25519 1 + +/* Allow U2F security keys for public key auth, with + * sk-ecdsa-sha2-nistp256@openssh.com or sk-ssh-ed25519@openssh.com keys. + * The corresponding DROPBEAR_ECDSA or DROPBEAR_ED25519 also needs to be set. + * This is currently server-only. */ +#define DROPBEAR_SK_KEYS 1 + +/* RSA must be >=1024 */ +#define DROPBEAR_DEFAULT_RSA_SIZE 2048 +/* DSS is always 1024 */ +/* ECDSA defaults to largest size configured, usually 521 */ +/* Ed25519 is always 256 */ + +/* Add runtime flag "-R" to 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. */ +#define DROPBEAR_DELAY_HOSTKEY 1 + + +/* 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) + * + * 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 ~2,5kB 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 + */ +#define DROPBEAR_DH_GROUP14_SHA1 1 +#define DROPBEAR_DH_GROUP14_SHA256 1 +#define DROPBEAR_DH_GROUP16 0 +#define DROPBEAR_CURVE25519 1 +#define DROPBEAR_ECDH 1 +#define DROPBEAR_DH_GROUP1 0 + +/* 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 + * 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) */ +#define DROPBEAR_ZLIB_WINDOW_BITS 15 + +/* Whether to do reverse DNS lookups. */ +#define DO_HOST_LOOKUP 0 + +/* Whether to print the message of the day (MOTD). */ +#define DO_MOTD 1 +#define MOTD_FILENAME "/etc/motd" + +/* 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). + * 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. */ +#define DROPBEAR_SVR_PAM_AUTH 0 + +/* ~/.ssh/authorized_keys authentication. + * You must define DROPBEAR_SVR_PUBKEY_AUTH in order to use plugins. */ +#define DROPBEAR_SVR_PUBKEY_AUTH 1 + +/* Whether to take public key options in + * authorized_keys file into account */ +#define DROPBEAR_SVR_PUBKEY_OPTIONS 1 + +/* Set this to 0 if your system does not have multiple user support. + (Linux kernel CONFIG_MULTIUSER option) + The resulting binary will not run on a normal system. */ +#define DROPBEAR_SVR_MULTIUSER 1 + +/* Client authentication options */ +#define DROPBEAR_CLI_PASSWORD_AUTH 1 +#define DROPBEAR_CLI_PUBKEY_AUTH 1 + +/* A default argument for dbclient -i <privatekey>. + * Homedir is prepended if path begins with ~/ + */ +#define DROPBEAR_DEFAULT_CLI_AUTHKEY "~/.ssh/id_dropbear" + +/* 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 */ +#define DROPBEAR_CLI_ASKPASS_HELPER 0 + +/* Save a network roundtrip by sendng a real auth request immediately after + * 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 + +/* 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 */ +#define MAX_UNAUTH_PER_IP 5 + +/* And then a global limit to avoid chewing memory if connections + * come from many IPs */ +#define MAX_UNAUTH_CLIENTS 30 + +/* Default maximum number of failed authentication tries (server option) */ +/* -T server option overrides */ +#define MAX_AUTH_TRIES 10 + +/* Delay introduced before closing an unauthenticated session (seconds). + Disabled by default, can be set to say 30 seconds to reduce the speed + of password brute forcing. Note that there is a risk of denial of + service by setting this */ +#define UNAUTH_CLOSE_DELAY 0 + +/* The default file to store the daemon's process ID, for shutdown + * scripts etc. This can be overridden with the -P flag. + * Homedir is prepended if path begins with ~/ + */ +#define DROPBEAR_PIDFILE "/var/run/dropbear.pid" + +/* 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 and set DROPBEAR_SFTPSERVER. + * The sftp-server program is not provided by Dropbear itself. + * Homedir is prepended if path begins with ~/ + */ +#define DROPBEAR_SFTPSERVER 1 +#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 DROPBEAR_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 0 + +/* 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 */ +#define DEFAULT_KEEPALIVE 0 + +/* 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 */ +#define DEFAULT_KEEPALIVE_LIMIT 3 + +/* Ensure that data is received within IDLE_TIMEOUT seconds. This can +be overridden at runtime with -I. 0 disables idle timeouts */ +#define DEFAULT_IDLE_TIMEOUT 0 + +/* The default path. This will often get replaced by the shell */ +#define DEFAULT_PATH "/usr/bin:/bin" +#define DEFAULT_ROOT_PATH "/usr/sbin:/usr/bin:/sbin:/bin" + +#endif /* DROPBEAR_DEFAULT_OPTIONS_H_ */ |