  A Mobile ad hoc Network or MANET is a wireless network of mobile devices that
has the ability to self-configure and self-organise and is characterised by an
absence of centralised administration and network infrastructure. An
appreciable number of routing protocols used in a typical MANET have left the
critical aspect of security out of consideration by assuming that all of its
constituent nodes are trustworthy and non-malicious. In this paper, we discuss
some of the major threats that such networks are vulnerable to, because of
these inherently insecure protocols. The focus is specifically on the
source-initiated and on-demand routing protocols. Further, solutions and
modifications to these protocols that have been proposed over time, enabling
them to mitigate the aforementioned threats to some extent, are also analysed.
