update the networking course information

Author: vladak

network.tex

@@ -113,10 +113,10 @@
 \item Ports below 1024 are reserved and additional privileges are needed to use
 them.  For example, \emph{root} can access those.  See \texttt{/etc/services}
 for the textual database of port numbers and corresponding service names.
-\item To learn about networking and the Internet in general, we very much
-recommend networking lectures by
-ifdef([[[NOSPELLCHECK]]], [[[Ji\v{r}\'{i} Peterka]]]).  You can either
-attend them at MFF~UK or you can find those online.
+\item To learn about networking and the Internet in general,
+see the Computer Networks (NSWI090) course.
+There are also on-line materials (\url{https://www.earchiv.cz/l226/index.php3}
+by ifdef([[[NOSPELLCHECK]]], [[[Ji\v{r}\'{i} Peterka]]]).
 \item \emph{IP} -- protocol of the internet layer within the TCP/IP network
 stack, provides data transfer between two interfaces identified by an IP
 address.  It is unreliable.  Provides routing and fragmentation.  Defined in