Mercurial > dropbear
view libtomcrypt/demos/constants.c @ 1790:42745af83b7d
Introduce extra delay before closing unauthenticated sessions
To make it harder for attackers, introduce a delay to keep an
unauthenticated session open a bit longer, thus blocking a connection
slot until after the delay.
Without this, while there is a limit on the amount of attempts an attacker
can make at the same time (MAX_UNAUTH_PER_IP), the time taken by dropbear to
handle one attempt is still short and thus for each of the allowed parallel
attempts many attempts can be chained one after the other. The attempt rate
is then:
"MAX_UNAUTH_PER_IP / <process time of one attempt>".
With the delay, this rate becomes:
"MAX_UNAUTH_PER_IP / UNAUTH_CLOSE_DELAY".
author | Thomas De Schampheleire <thomas.de_schampheleire@nokia.com> |
---|---|
date | Wed, 15 Feb 2017 13:53:04 +0100 |
parents | e9dba7abd939 |
children |
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis * * LibTomCrypt is a library that provides various cryptographic * algorithms in a highly modular and flexible manner. * * The library is free for all purposes without any express * guarantee it works. */ #include "tomcrypt.h" #if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L #include <libgen.h> #else #define basename(x) x #endif /** @file demo_crypt_constants.c Demo how to get various constants to dynamic languages like Python Larry Bugbee, February 2013 */ static void _print_line(const char* cmd, const char* desc) { printf(" %-16s - %s\n", cmd, desc); } int main(int argc, char **argv) { if (argc == 1) { /* given a specific constant name, get and print its value */ char name[] = "CTR_COUNTER_BIG_ENDIAN"; int value; char *names_list; unsigned int names_list_len; if (crypt_get_constant(name, &value) != 0) exit(EXIT_FAILURE); printf("\n %s is %d \n\n", name, value); /* get and print the length of the names (and values) list */ if (crypt_list_all_constants(NULL, &names_list_len) != 0) exit(EXIT_FAILURE); printf(" need to allocate %u bytes \n\n", names_list_len); /* get and print the names (and values) list */ if ((names_list = malloc(names_list_len)) == NULL) exit(EXIT_FAILURE); if (crypt_list_all_constants(names_list, &names_list_len) != 0) exit(EXIT_FAILURE); printf(" supported constants:\n\n%s\n\n", names_list); free(names_list); } else if (argc == 2) { if (strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0) { char* base = strdup(basename(argv[0])); printf("Usage: %s [-a] [-s name]\n\n", base); _print_line("<no argument>", "The old behavior of the demo"); _print_line("-a", "Only lists all constants"); _print_line("-s name", "List a single constant given as argument"); _print_line("-h", "The help you're looking at"); free(base); } else if (strcmp(argv[1], "-a") == 0) { char *names_list; unsigned int names_list_len; /* get and print the length of the names (and values) list */ if (crypt_list_all_constants(NULL, &names_list_len) != 0) exit(EXIT_FAILURE); /* get and print the names (and values) list */ if ((names_list = malloc(names_list_len)) == NULL) exit(EXIT_FAILURE); if (crypt_list_all_constants(names_list, &names_list_len) != 0) exit(EXIT_FAILURE); printf("%s\n", names_list); free(names_list); } } else if (argc == 3) { if (strcmp(argv[1], "-s") == 0) { int value; if (crypt_get_constant(argv[2], &value) != 0) exit(EXIT_FAILURE); printf("%s,%u\n", argv[2], value); } } return 0; } /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */