Add the rest of university notes

docs/lectures/acn/09_DTN_security.md

@@ -4,7 +4,7 @@
 
 ##### Interplanetary communication
 
-<img src="/lectures/acn/img/o.png" alt="DTN in space" style="zoom:50%;" />
+<img src="img/o.png" alt="DTN in space" style="zoom:50%;" />
 
 > **Characteristics**
 >
@@ -52,7 +52,7 @@
 >- High propagation delay
 >- Asymmetric data rate
 >
->![img](/lectures/acn/img/p.png)
+>![img](img/p.png)
 >
 >**Security**
 >
@@ -127,7 +127,7 @@ Based on the *bundle* protocol
 * Access Control (only legit users with right permissions)
 * Limited protection from DoS attacks
 
-![img](/lectures/acn/img/q.png)
+![img](img/q.png)
 
 - Payload Security Header is computed once at the source bundle agent, carried unchanged, and checked at the destination bundle agent (and possibly also security boundary bundle agents)