Xjyuk

I know this is a shit question, but I don't know what to do because I don't have much time left.

I need a diagram like this for my thesis:

I already tried making this with tikz. First I tried it with the libraries shapes and arrows on my own with node and path, but I couldn't do it.
Then I tried it with the trees library, but it also didn't work out how I wanted.
Now I need you help. I guess it's just a few lines of code.

Here is the code of my best attempt so far

documentclass[a4,border=10pt]article
 usepackagetikz
 usetikzlibraryshapes,arrows

 begindocument
 % Define block styles
 tikzstyledecision = [diamond, draw, fill=blue!20, 
 text width=4.5em, text badly centered, node distance=3cm, inner sep=0pt]
 tikzstyleblock = [rectangle, draw, fill=blue!20, 
 text width=5em, text centered, minimum height=4em]
 tikzstyleline = [draw, -latex']

 begintikzpicture[node distance = 2cm, auto]
 % Place nodes
 node [decision] (outsideThreat) Bedrohung von außen?;
 node [block, left of=outsideThreat, below of=outsideThreat] (firewall) Firewall;
 node [decision, right of=outsideThreat, below of=outsideThreat] (knownThreat) Bedrohung bekannt?;
 node [block, below of=knownThreat, left of=knownThreat] (idsAds) IDS/ADS;
 node [block, below of=knownThreat, right of=knownThreat] (honeypots) Honeypots;
 % Draw edges
 path [line] (outsideThreat) --(outsideThreat-|firewall) -- node yes (firewall);
 path [line] (outsideThreat) --(knownThreat|-outsideThreat) -- node no (knownThreat);
 path [line] (firewall) -- (knownThreat);
 path [line] (knownThreat) --(knownThreat-|idsAds) -- node yes (idsAds); 
 path [line] (knownThreat) --(honeypots|-knownThreat) -- node no (honeypots);
 endtikzpicture
 enddocument

This code produces this output:

I can't manage to get the Firewall block and the Bedrohung bekannt? decision on the same level horizontally. And don't know how to achieve the exact arrows of my example above.

Here is one way!

documentclass[tikz,border=3mm]standalone
usetikzlibraryshapes.geometric 
begindocument
begintikzpicture[thick,>=stealth]
tikzsetbox/.style=
 draw,minimum height=1.2cm,minimum width=3cm
path 
(0,2) node[diamond,draw] (d1) decision1
(-5,-2) node[box] (b1) block1
(4,-2) node[diamond,draw] (d2) decision2
++(-90:1.5) coordinate (d2s) 
+(4,-2) node[box] (b3) block3
+(-3,-1.5) node[box] (b4) block4;
draw (0,0)--(d1);
draw[->] (0,0)-|(d2) node[pos=.25,above]no;
draw[->] (0,0)-|(b1) node[pos=.25,above]yes;
draw[->] (b1)--(d2) node[midway,above]some condition;
draw (d2)--(d2s);
draw[->] (d2s)-|(b3) node[pos=.25,above]no;
draw[->] (d2s)-|(b4) node[pos=.25,above]yes;
endtikzpicture
enddocument

With forest you can automatize several things. In particular, you can leave the decision whether or not a node is a decision to forest.

documentclass[tikz,border=3.14mm]standalone
usepackage[edges]forest
usetikzlibraryshapes.geometric
begindocument
beginforest
forked edges,
for tree=l sep=3em,s sep=3em,edge=-stealth,
 where n children=2diamondrectangle,inner sep=1ex,draw,
 if n=1edge label=node [pos=0.25, below] yes edge label=node [pos=0.25, below] no 
[decision 1
 [block 1,alias=b1]
 [decision 2,alias=d2
 [block 2]
 [block 3]
 ]
]
draw[-stealth] (b1) -- (d2) node[midway,above]pft;
endforest
enddocument

For fun, a simple pstricks code:

documentclass[border=6pt]standalone%
usepackage[utf8]inputenc
usepackage[T1]fontenc
usepackagepst-node
newcommandpsstrutrule[-0.55cm]0pt1.25cm
newcommanddiastrutrule[-0.65cm]0pt1.45cm%

begindocument

sffamilyeverymathdisplaystyle%
pssetframesep=1pt, arrows=->, arrowinset=0.1,linejoin=1
beginpsmatrix[rowsep=2.5cm, colsep=2cm, emnode=r]% 
%%% Nodes
& dianode[framesep = -2pt]d1diastrut Decision 1\
[name=b1] psframeboxmakebox[2.5cm]psstrut block 1 & & dianode[framesep = -2pt]d2diastrut Decision 2\
 & [name=b2] psframeboxmakebox[2.5cm]psstrut block 2 & & [name=b3] psframeboxmakebox[2.5cm]psstrut block 3
 %%% Node connections
 pssetangleA=-90, angleB=90, armA=0.8cm, armB=0.8cm, labelsep=2pt
 ncanglesd1b1nbputyes
 ncanglesd1d2naputno
 nclineb1d2naputsome condition
 ncanglesd2b2nbputyes
 ncanglesd2b3naputno
 endpsmatrix

enddocument 

Here is the code of my best attempt so far

documentclass[a4,border=10pt]article
 usepackagetikz
 usetikzlibraryshapes,arrows

 begindocument
 % Define block styles
 tikzstyledecision = [diamond, draw, fill=blue!20, 
 text width=4.5em, text badly centered, node distance=3cm, inner sep=0pt]
 tikzstyleblock = [rectangle, draw, fill=blue!20, 
 text width=5em, text centered, minimum height=4em]
 tikzstyleline = [draw, -latex']

 begintikzpicture[node distance = 2cm, auto]
 % Place nodes
 node [decision] (outsideThreat) Bedrohung von außen?;
 node [block, left of=outsideThreat, below of=outsideThreat] (firewall) Firewall;
 node [decision, right of=outsideThreat, below of=outsideThreat] (knownThreat) Bedrohung bekannt?;
 node [block, below of=knownThreat, left of=knownThreat] (idsAds) IDS/ADS;
 node [block, below of=knownThreat, right of=knownThreat] (honeypots) Honeypots;
 % Draw edges
 path [line] (outsideThreat) --(outsideThreat-|firewall) -- node yes (firewall);
 path [line] (outsideThreat) --(knownThreat|-outsideThreat) -- node no (knownThreat);
 path [line] (firewall) -- (knownThreat);
 path [line] (knownThreat) --(knownThreat-|idsAds) -- node yes (idsAds); 
 path [line] (knownThreat) --(honeypots|-knownThreat) -- node no (honeypots);
 endtikzpicture
 enddocument

This code produces this output:

I can't manage to get the Firewall block and the Bedrohung bekannt? decision on the same level horizontally. And don't know how to achieve the exact arrows of my example above.