Find all tuples $ (x_1,x_2,x_3,x_4,x_5,x_6)$ of non-negative integers, such that the following system of equations holds:
$ x_1x_2(1\minus{}x_3)\equal{}x_4x_5 \\
x_2x_3(1\minus{}x_4)\equal{}x_5x_6 \\
x_3x_4(1\minus{}x_5)\equal{}x_6x_1 \\
x_4x_5(1\minus{}x_6)\equal{}x_1x_2 \\
x_5x_6(1\minus{}x_1)\equal{}x_2x_3 \\
x_6x_1(1\minus{}x_2)\equal{}x_3x_4$
1. **Analyzing the given system of equations:**
   \[
   \begin{cases}
   x_1 x_2 (1 - x_3) = x_4 x_5 \\
   x_2 x_3 (1 - x_4) = x_5 x_6 \\
   x_3 x_4 (1 - x_5) = x_6 x_1 \\
   x_4 x_5 (1 - x_6) = x_1 x_2 \\
   x_5 x_6 (1 - x_1) = x_2 x_3 \\
   x_6 x_1 (1 - x_2) = x_3 x_4
   \end{cases}
   \]

2. **Identifying zeros in the tuples:**
   From the first equation \(x_1 x_2 (1 - x_3) = x_4 x_5\), if \(x_3 \neq 1\), then either \(x_1 = 0\) or \(x_2 = 0\) or \(x_4 x_5 = 0\). This implies that at least one of \(x_3, x_4, x_5\) must be zero. Similarly, analyzing the other equations, we conclude that at least one of \(x_4, x_5, x_6\), \(x_5, x_6, x_1\), \(x_6, x_1, x_2\), \(x_1, x_2, x_3\), and \(x_2, x_3, x_4\) must be zero.

3. **Assuming \(x_3 = 0\):**
   - **Case 1: \(x_6 = 0\)**
     \[
     \begin{cases}
     x_1 x_2 = x_4 x_5 \\
     x_2 \cdot 0 \cdot (1 - x_4) = x_5 \cdot 0 \\
     0 \cdot x_4 (1 - x_5) = 0 \cdot x_1 \\
     x_4 x_5 (1 - 0) = x_1 x_2 \\
     x_5 \cdot 0 (1 - x_1) = x_2 \cdot 0 \\
     0 \cdot x_1 (1 - x_2) = 0 \cdot x_4
     \end{cases}
     \]
     This simplifies to \(x_1 x_2 = x_4 x_5\), which is satisfied for any non-negative integers \(x_1, x_2, x_4, x_5\) such that \(x_1 x_2 = x_4 x_5\).

   - **Case 2: \(x_6 \neq 0\)**
     - If \(x_1 = 0\):
       \[
       \begin{cases}
       0 \cdot x_2 = x_4 x_5 \\
       x_2 \cdot 0 \cdot (1 - x_4) = x_5 x_6 \\
       0 \cdot x_4 (1 - x_5) = x_6 \cdot 0 \\
       x_4 x_5 (1 - x_6) = 0 \cdot x_2 \\
       x_5 x_6 (1 - 0) = x_2 \cdot 0 \\
       x_6 \cdot 0 (1 - x_2) = 0 \cdot x_4
       \end{cases}
       \]
       This simplifies to \(x_4 x_5 = 0\). Since \(x_6 \neq 0\), we must have \(x_5 = 0\). This satisfies the equations.

     - If \(x_5 = 0\):
       \[
       \begin{cases}
       x_1 x_2 = 0 \\
       x_2 \cdot 0 \cdot (1 - x_4) = 0 \cdot x_6 \\
       0 \cdot x_4 (1 - 0) = x_6 \cdot x_1 \\
       x_4 \cdot 0 (1 - x_6) = x_1 x_2 \\
       0 \cdot x_6 (1 - x_1) = x_2 \cdot 0 \\
       x_6 x_1 (1 - x_2) = 0 \cdot x_4
       \end{cases}
       \]
       This simplifies to \(x_1 = 0\). This satisfies the equations.

4. **Generalizing the solutions:**
   The solutions are of the form:
   - \((ab, cd, 0, ac, bd, 0)\)
   - \((0, x, 0, 0, y, 0)\)
   - \((x, 0, 0, 0, y, 0)\)
   - \((0, g, 0, h, 0, i)\)
   and any cyclic permutation of these tuples, where \(a, b, c, d\) are any positive integers and \(x, y, g, h, i\) are any non-negative integers.

The final answer is \( \boxed{ (ab, cd, 0, ac, bd, 0) } \), \((0, x, 0, 0, y, 0)\), \((x, 0, 0, 0, y, 0)\), \((0, g, 0, h, 0, i)\) and any cyclic permutation of these tuples, where \(a, b, c, d\) are any positive integers and \(x, y, g, h, i\) are any non-negative integers.