Linux Journal Article Posted - Single Packet Authorization Part II
04 April, 2007
The current issue (May '07) of the Linux Journal,
contains part II of my series on Single Packet Authorization (SPA). The article is
entitled Protecting SSH Servers with Single Packet Authorization, and appears to not
be available yet through the LJ website so I suppose that it may only be in the print edition
for a while. Part II is a hands-on treatment of
fwknop operations, and covers SPA with both symmetric and asymmetric
ciphers. here is a short excerpt from the article:
"...This article gets away from theory and
concentrates on the practical application of SPA with fwknop and iptables to
protect SSHD from reconnaissance and attack. With this setup on a Linux
system, no one will be able to tell that SSHD is even listening under an nmap
scan, and only authenticated and authorized clients will be able to
communicate with SSHD.To begin, we require some information about configuration and network architecture. This article assumes that you have installed the latest version of fwknop (1.0.1 as of this writing) on the same system where SSHD and iptables is running. You can download fwknop from http://www.cipherdyne.org/fwknop/ and install either from the source tar archive by running the install.pl script, or install via the RPM for RPM- based Linux distributions..."
