Compilation error

[LLL2000L]

Hello, I got an error when compiling make: [33%] Linking C executable http_server /usr/bin/ld: /usr/lib/x86_64-linux-gnu/libevent.a(evutil_rand.o): in function arc4_stir': (.text+0x2e2): undefined reference to sysctl' collect2: error: ld returned 1 exit status make[2]: ***[bin/CMakeFiles/http_server.dir/build.make:150:bin/http_server] Error 1 make[1]: ***[CMakeFiles/Makefile2:289:bin/CMakeFiles/http_server.dir/all] Error 2 make: ***[Makefile:146:all] Error 2 I still can't find the reason. What's the solution? I would be grateful if you could answer my question