It is not possible to configure the current commit (9d5e6f0709c3..) on Centos 5.8

[sasanj]

This is what happens on the box:

[src]$ git clone "git://github.com/jvinet/knock.git"
Cloning into 'knock'...
remote: Counting objects: 80, done.
remote: Compressing objects: 100% (62/62), done.
remote: Total 80 (delta 26), reused 70 (delta 16)
Receiving objects: 100% (80/80), 101.50 KiB, done.
Resolving deltas: 100% (26/26), done.
[src]$ cd knock
[src/knock]$ git status
# On branch master
nothing to commit (working directory clean)
[src/knock]$ git show
commit 7666f2e86e18d482eaad5fe1fea46d87d80b0555
Merge: 42c6c9e 9d5e6f0
Author: Judd Vinet 
Date:   Thu Feb 16 09:23:31 2012 -0800

    Merge pull request #1 from Flameeyes/master

    Proper autotool usage in knock

[src/knock]$ aclocal
[src/knock]$ autoconf
configure.ac:8: error: possibly undefined macro: AC_USE_SYSTEM_EXTENSIONS
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.
[src/knock]$ head -1 configure.ac
AC_PREREQ(2.59)
[src/knock]$ autoconf --version
autoconf (GNU Autoconf) 2.59 
Written by David J. MacKenzie and Akim Demaille.
[src/knock]$ automake --version
automake (GNU automake) 1.9.6

There are other errors, for example dist-xz is not recognized. automake also complains:'dist_doc_DATA' is used but 'docdir' is undefined

With this configure.ac one needs an autoconf 2.60+ and automake 1.10.

[jvinet]

Should be fine on CentOS 6+