Package: netcat-openbsd Version: 1.195-1 Followup-For: Bug #747646 Performing this test with blank packets still works without the server seeing anything.
-- System Information: Debian Release: buster/sid APT prefers testing APT policy: (500, 'testing') Architecture: amd64 (x86_64) Foreign Architectures: i386 Kernel: Linux 4.18.0-2-amd64 (SMP w/8 CPU cores) Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Init: systemd (via /run/systemd/system) LSM: AppArmor: enabled Versions of packages netcat-openbsd depends on: ii libbsd0 0.9.1-1 ii libc6 2.27-8 netcat-openbsd recommends no packages. netcat-openbsd suggests no packages. -- no debconf information
--- ../netcat-openbsd-1.195/netcat.c 2018-11-09 12:15:42.000000000 -0500 +++ netcat.c 2018-11-08 23:07:38.858140209 -0500 @@ -1862,15 +1862,15 @@ { int i, t; - if ((write(s, "X", 1) != 1) || - ((write(s, "X", 1) != 1) && (errno == ECONNREFUSED))) + if ((write(s, "", 1) != 1) || + ((write(s, "", 1) != 1) && (errno == ECONNREFUSED))) return -1; /* Give the remote host some time to reply. */ for (i = 0, t = (timeout == -1) ? UDP_SCAN_TIMEOUT : (timeout / 1000); i < t; i++) { sleep(1); - if ((write(s, "X", 1) != 1) && (errno == ECONNREFUSED)) + if ((write(s, "", 1) != 1) && (errno == ECONNREFUSED)) return -1; } return 1;