Set up your Tor to offer a hidden service, and use a hostname destination, like localhost:80, on the HiddenServicePort line. Then ifdown eth0 so you have no network. Then run `valgrind tor --verify-config` and voila, you get this complaint: ``` Configuration was valid ==31082== Invalid free() / delete / delete[] / realloc() ==31082== at 0x4C29E90: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==31082== by 0x63A116B: __libc_freeres (in /lib/x86_64-linux-gnu/libc-2.19.so) ==31082== by 0x4A236CC: _vgnU_freeres (in /usr/lib/valgrind/vgpreload_core-amd64-linux.so) ==31082== by 0x628CAEA: __run_exit_handlers (exit.c:97) ==31082== by 0x628CB74: exit (exit.c:104) ==31082== by 0x6276B4B: (below main) (libc-start.c:321) ==31082== Address 0x65fa2d0 is 0 bytes inside data symbol "noai6ai_cached" ``` If you leave off the --verify-config, you can trigger the same thing, by starting, and then after a while ctrl-C'ing your Tor so it exits, at which point you get something similar: ``` ==8895== Invalid free() / delete / delete[] / realloc() ==8895== at 0x4C29E90: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==8895== by 0x63A116B: __libc_freeres (in /lib/x86_64-linux-gnu/libc-2.19.so) ==8895== by 0x4A236CC: _vgnU_freeres (in /usr/lib/valgrind/vgpreload_core-amd64-linux.so) ==8895== by 0x628CAEA: __run_exit_handlers (exit.c:97) ==8895== by 0x628CB74: exit (exit.c:104) ==8895== by 0x154686: process_signal (main.c:2601) ==8895== by 0x154686: signal_callback (main.c:2583) ==8895== by 0x5361A14: event_base_loop (in /usr/lib/x86_64-linux-gnu/libevent-2.0.so.5.1.9) ==8895== by 0x152B53: run_main_loop_once (main.c:2514) ==8895== by 0x152B53: run_main_loop_until_done (main.c:2568) ==8895== by 0x152B53: do_main_loop (main.c:2481) ==8895== by 0x1562B4: tor_main (main.c:3628) ==8895== by 0x14E408: main (tor_main.c:34) ==8895== Address 0x65fa2d0 is 0 bytes inside data symbol "noai6ai_cached" ``` It's not clear to me what is going wrong.