Installing Firewalk turned out to be more complicated than I thought it would be. There were some compilation issues and some library errors.
The chief amongst them was:

checking for arp_get in -ldnet... no
configure: error: No libdnet?  http://libdnet.sourceforge.net.

I did install libdnet using aptitude but it did not do the trick. Thereafer, searching a few forums got me this information. The “Libdnet” that Firewalk looks for is libdumbnet1 in the ubuntu language.
So I got the Debian packages from the following links:
libdnet1
libdnet-dev
I continued to get that error and no wonder because there was nothing in /usr/lib.
So I executed the following commands :

$ cd /usr/lib
$ sudo ln -s libdumbnet.so libdnet.so
$ cd /usr/include
$ sudo ln -s dumbnet.h dnet.h

Then there was a compilation error:

firewalk.c: In function ‘firewalk’:
firewalk.c:193: error: label at end of compound statement
make[1]: *** [firewalk.o] Error 1
make[1]: Leaving directory `/home/trance/Desktop/Firewalk/src'
make: *** [all-recursive] Error 1

So then opening the firewalk.c file in vim (and following up on line 193) showed that the “break;” statement was missing after default: switch statement.
So then I added the the following characters (without quotes) “break;” at a line above the comment as shown below:

                    default:
                        break;
                        /* empty */

$ ./configure
$ make
$ sudo make install
$ sudo cp man/firewalk.8 /usr/local/man/man8

Now firewalk was installed and ready to use!