diff --git a/build.sh b/build.sh
index 0418df41..2638c0d8 100755
--- a/build.sh
+++ b/build.sh
@@ -6,6 +6,7 @@
 #   --clean         Clean before build
 #   --full          Full rebuild (autoreconf + configure + make)
 #   --asan          Build with AddressSanitizer (debug)
+#   --hardened      Build with compiler security hardening flags
 #   -j[N]           Build with N parallel jobs (default: 4)
 
 set -e  # Exit on error
@@ -23,8 +24,10 @@ fi
 CLEAN=0
 FULL_REBUILD=0
 USE_ASAN=0
+USE_HARDENED=0
 JOBS="-j4"
 MAKE_ARGS=""
+HARDEN_FLAGS=""
 
 while [[ $# -gt 0 ]]; do
     case $1 in
@@ -35,6 +38,7 @@ while [[ $# -gt 0 ]]; do
             echo "  --clean         Clean before build"
             echo "  --full          Full rebuild (autoreconf + configure + make)"
             echo "  --asan          Build with AddressSanitizer"
+            echo "  --hardened      Build with compiler security hardening flags"
             echo "  -j[N]           Build with N parallel jobs (default: 4)"
             exit 0
             ;;
@@ -50,6 +54,10 @@ while [[ $# -gt 0 ]]; do
             USE_ASAN=1
             shift
             ;;
+        --hardened)
+            USE_HARDENED=1
+            shift
+            ;;    
         -j*)
             JOBS="$1"
             shift
@@ -135,6 +143,8 @@ if [ ! -f Makefile ]; then
     echo "Running ./configure..."
     if [ "$USE_ASAN" -eq 1 ]; then
         ./configure CFLAGS="-g -Og -fsanitize=address -fno-omit-frame-pointer -fno-pie" LDFLAGS="-no-pie"
+    elif [ "$USE_HARDENED" -eq 1 ]; then
+        ./configure --enable-hardening
     else
         ./configure
     fi
@@ -151,6 +161,14 @@ if [ "$USE_ASAN" -eq 1 ]; then
     (cd lib && make clean $JOBS $MAKE_ARGS 2>&1 && make "CFLAGS+=$AF" "LDFLAGS+=$AL" $JOBS $MAKE_ARGS 2>&1) || { echo "lib build failed"; exit 1; }
     (cd src && make clean $JOBS $MAKE_ARGS 2>&1 && make "CFLAGS+=$AF" "LDFLAGS+=$AL" $JOBS $MAKE_ARGS 2>&1) || { echo "src build failed"; exit 1; }
     BUILD_SUCCESS=1
+elif [ "$USE_HARDENED" -eq 1 ]; then
+    echo "(Hardening flags enabled)"
+    HF="-D_FORTIFY_SOURCE=2 -fstack-protector-strong -fstack-clash-protection -Wformat=2 -Wformat-overflow=2 -fPIE"
+    HL="-Wl,-z,relro -Wl,-z,now -pie"
+    (cd lib && make clean $JOBS $MAKE_ARGS 2>&1 && make "CFLAGS+=$HF" "LDFLAGS+=$HL" $JOBS $MAKE_ARGS 2>&1) || { echo "lib build failed"; exit 1; }
+    (cd src && make clean $JOBS $MAKE_ARGS 2>&1 && make "CFLAGS+=$HF" "LDFLAGS+=$HL" $JOBS $MAKE_ARGS 2>&1) || { echo "src build failed"; exit 1; }
+    (cd tests && make clean $JOBS $MAKE_ARGS 2>&1 && make "CFLAGS+=$HF" "LDFLAGS+=$HL" $JOBS $MAKE_ARGS 2>&1) || { echo "tests build failed"; exit 1; }
+    BUILD_SUCCESS=1
 else
     make $JOBS $MAKE_ARGS 2>&1 | tee build.log
     if [ ${PIPESTATUS[0]} -eq 0 ]; then
diff --git a/configure.ac b/configure.ac
index d1cd998c..a30ee037 100644
--- a/configure.ac
+++ b/configure.ac
@@ -55,6 +55,20 @@ fi
 
 AM_CONDITIONAL([USE_OPENSSL], [test "x$with_openssl" = "xyes"])
 
+# ==================== HARDENING ====================
+AC_ARG_ENABLE([hardening],
+    AS_HELP_STRING([--enable-hardening], [Enable compiler security hardening (FORTIFY, stack protector, PIE, RELRO)]),
+    [enable_hardening=$enableval],
+    [enable_hardening=no])
+
+if test "x$enable_hardening" = "xyes"; then
+    HARDEN_CFLAGS="-D_FORTIFY_SOURCE=2 -fstack-protector-strong -fstack-clash-protection -Wformat=2 -Wformat-overflow=2 -fPIE"
+    HARDEN_LDFLAGS="-Wl,-z,relro -Wl,-z,now -pie"
+    CFLAGS="$CFLAGS $HARDEN_CFLAGS"
+    LDFLAGS="$LDFLAGS $HARDEN_LDFLAGS"
+    AC_MSG_NOTICE([Hardening flags enabled: $HARDEN_CFLAGS])
+fi
+
 # ==================== НАДЁЖНЫЙ ДЕТЕКТ WINDOWS ====================
 AC_MSG_CHECKING([for Windows])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
diff --git a/doc/_plan.txt b/doc/_plan.txt
new file mode 100644
index 00000000..731fc5b3
--- /dev/null
+++ b/doc/_plan.txt
@@ -0,0 +1,3 @@
+План доработок
+[ ] продумать архитектуру репликации таблицы узлов группы
+[ ] добавить узлы хелперы (для проксирования трафика)
diff --git a/src/control_server.c b/src/control_server.c
index 4c15291e..fb394fa4 100644
--- a/src/control_server.c
+++ b/src/control_server.c
@@ -479,6 +479,12 @@ static void client_read_callback(socket_t fd, void* arg) {
     struct control_client* client = (struct control_client*)arg;
     struct control_server* server = client->server;
 
+    if (client->recv_len >= ETCPMON_MAX_MSG_SIZE) {
+        DEBUG_ERROR(DEBUG_CATEGORY_CONTROL, "Control recv buffer overflow (pre-check)");
+        close_client(server, client);
+        return;
+    }
+
     /* Read available data */
     uint8_t* buf = client->recv_buffer + client->recv_len;
     size_t buf_space = ETCPMON_MAX_MSG_SIZE - client->recv_len;
@@ -801,7 +807,7 @@ static void handle_client_data(struct control_server* server, struct control_cli
                             u_free(text);
                         }
                     } else {
-                        DEBUG_WARN(DEBUG_CATEGORY_CONTROL, "Unknown action received: '%s'", cmd->action);
+                        DEBUG_WARN(DEBUG_CATEGORY_CONTROL, "Unknown action received: '%.32s'", cmd->action);
                     }
                 }
                 break;
diff --git a/tools/chatgui/build_linux.sh b/tools/chatgui/build_linux.sh
new file mode 100755
index 00000000..dac1f82e
--- /dev/null
+++ b/tools/chatgui/build_linux.sh
@@ -0,0 +1,32 @@
+#!/bin/bash
+set -eo pipefail
+
+# --- dependencies ---
+PKGS="cmake librlottie-dev zlib1g-dev qtbase5-dev libssl-dev"
+MISSING=""
+for p in $PKGS; do
+    dpkg -s "$p" &>/dev/null || MISSING="$MISSING $p"
+done
+
+if [ -n "$MISSING" ]; then
+    echo "Installing missing packages:$MISSING"
+    sudo apt update && sudo apt install -y $MISSING
+else
+    echo "All dependencies OK"
+fi
+
+# --- build ---
+SRCDIR="$(cd "$(dirname "$0")" && pwd)"
+BUILDDIR="$SRCDIR/build"
+JOBS="${JOBS:-$(nproc)}"
+
+echo "Source: $SRCDIR"
+echo "Build:  $BUILDDIR"
+echo "Jobs:   $JOBS"
+echo ""
+
+[ -f "$BUILDDIR/Makefile" ] || cmake -S "$SRCDIR" -B "$BUILDDIR"
+cmake --build "$BUILDDIR" -j"$JOBS"
+
+echo ""
+echo "OK. Run: $BUILDDIR/chatgui"