wolfSentry is the wolfSSL IDPS (Intrusion Detection and Prevention System). It is mainly used as a library, but can also be used as part of a kernel module.

At a high level, wolfSentry is a dynamically configurable logic hub, arbitrarily associating user-defined events with user-defined actions, contextualized by connection attributes, tracking the evolution of the client-server relationship. At a low level, wolfSentry is an embedded firewall engine (both static and fully dynamic), with O(log n) lookup of known hosts/netblocks.

wolfSentry will be fully integrated into the wolfSSL library, wolfMQTT, and wolfSSH, with optional in-tree call-ins and callbacks that give application developers turnkey IDPS across all network-facing wolfSSL products, with a viable zero-configuration option. These integrations will be available via simple --enable-wolfidps configure options in wolfSSL sibling products.

The wolfSentry engine will be dynamically configurable programmatically through an API, or from a textual input file supplied to the engine. Callback and client-server implementations will also be supplied that deliver advanced capabilities including remote logging through MQTT or syslog, and remote configuration and status queries, all cryptographically secured.

Notably, wolfSentry is designed from the ground up to function well in resource-constrained, bare-metal, and realtime environments, with algorithms to stay within designated maximum memory footprints and maintain deterministic throughput. Opportunities include RTOS IDPS, and IDPS for ARM silicon and other common embedded CPUs and MCUs. wolfSentry with dynamic firewalling can add as little as 64k to the code footprint, and 32k to the volatile state footprint, and can fully leverage the existing logic and state of applications and sibling libraries.

In its default build, wolfSentry depends on a POSIX runtime, specifically the heap allocator, clock_gettime, stdio, semaphore, and string APIs. However, these dependencies can be avoided with various build-time options. In particular, the recipe

make STATIC=1 SINGLETHREADED=1 NO_STDIO=1 EXTRA_CFLAGS='-DWOLFSENTRY_NO_CLOCK_BUILTIN -DWOLFSENTRY_NO_MALLOC_BUILTIN'

generates a libwolfsentry.a that depends on only a handful of basic string functions. Allocator and time callbacks must then be set in a struct wolfsentry_host_platform_interface supplied to wolfsentry_init().

Build and test libwolfsentry.a:

make -j test

Build verbosely:

make V=1 -j test

Build with artifacts in an alternate location (outside or in a subdirectory of the source tree):

make BUILD_TOP=./build -j test

Install from an alternate build location to a non-standard destination:

make BUILD_TOP=./build INSTALL_DIR=/usr INSTALL_LIBDIR=/usr/lib64 install

Build libwolfsentry.a and test it under various analyzers (memory and thread testing under full battery of valgrind and sanitizer tests):

make -j check

Build and test libwolfsentry.a without support for multithreading:

make -j SINGLETHREADED=1 test

Other available make flags are STATIC=1, STRIPPED=1, NO_JSON=1, and NO_JSON_DOM=1, and the defaults values for DEBUG, OPTIM, and C_WARNFLAGS can also be usefully overridden.

Build with a user-supplied makefile preamble to override defaults:

make -j USER_MAKE_CONF=Makefile.settings

(Makefile.settings can contain simple settings like OPTIM := -Os, or elaborate makefile code including additional rules and dependency mechanisms.)

Build the smallest simplest possible library:

make -j SINGLETHREADED=1 NO_STDIO=1 DEBUG= OPTIM=-Os EXTRA_CFLAGS='-DWOLFSENTRY_NO_CLOCK_BUILTIN -DWOLFSENTRY_NO_MALLOC_BUILTIN -DWOLFSENTRY_NO_ERROR_STRINGS -Wno-error=inline -Wno-inline'

Build and test with user settings:

make -j USER_SETTINGS_FILE=user_settings.h test

In the wolfSSL repository, see code in wolfsentry/test.h gated on WOLFSSL_WOLFSENTRY_HOOKS, including wolfsentry_store_endpoints(), wolfSentry_NetworkFilterCallback(), wolfsentry_setup(), and tcp_connect_with_wolfSentry(). See also code in examples/server/server.c and examples/client/client.c gated on WOLFSSL_WOLFSENTRY_HOOKS. Use configure --enable-wolfsentry to build with wolfSentry integration, and use --with-wolfsentry=/the/install/path if wolfSentry is installed in a nonstandard location. The wolfSSL test client/server can be loaded with user-supplied wolfSentry JSON configurations from the command line, using --wolfsentry-config <file>.

More comprehensive examples of API usage are in the wolfSentry repo in tests/unittests.c, particularly test_static_routes(), test_dynamic_rules(), and test_json().

Example JSON configuration files are at tests/test-config.json and tests/test-config-numeric.json. The latter differs only by the use of raw numbers rather than names for address families and protocols.