host to network long

def l2n(l, c):
    "host to network long"
    c = []
    c.append(int((l >> 24) & U32(0xFF)))
    c.append(int((l >> 16) & U32(0xFF)))
    c.append(int((l >>  8) & U32(0xFF)))
    c.append(int((l      ) & U32(0xFF)))
    return c