Network Security Hacks 
by Andrew Lockhart

The unconfirmed error reports are from readers.  They have not yet been 
approved or disproved by the author or editor and represent solely the
opinion of the reader.

Here's a key to the markup:
        [page-number]: serious technical mistake
        {page-number}: minor technical mistake
        <page-number>: important language/formatting problem
        (page-number): language change or minor formatting problem
        ?page-number?: reader question or request for clarification

This page was updated March 27, 2007.


UNCONFIRMED  errors and comments from readers: 


{17}  last line;
If you're using xdm, look for a file called Xservers and make sure it
contains a line similar to this:
0: local /usr/X11R6/bin/X -nolisten tcp

This line should read
0: local /usr/X11R6/bin/X vt05 -nolisten tcp

Note, the X server counts the vty from one, whereas BSD kernel
numbers the vty from zero. See /etc/ttys. This example will direct the
X server to run in /dev/ttyv4.



{72}  First code listing;
Reads:
# iptables -P INPUT -i lo -j ACCEPT
# iptables -P OUTPUT -o lo -j ACCEPT

Should Read:
# iptables -A INPUT -i lo -j ACCEPT
# iptables -A OUTPUT -o lo -j ACCEPT

{91}  (maybe) 5th paragraph;
in the "small and handy shell script" is the line
    ping -c $1 [etc]
which should be
   ping -c 1 $1 [etc]



[152]  Last quarter ;
You should insert a destination target for remote logging as example
when you specify the destination loghost on the previous page(151)
in the middle.

example after

  # *.emerg
  log { source(src) ....

  You should insert something like

  # Log every message to remote host without filtering
  log { source(src); destination(loghost); };

  Without this it's impossible to log to remote host ...



[303]  Chapter 10, Hack 92;
The text says:

To disable IP forwarding, run this:

# echo 1 > /proc/sys/net/ipv4/ip_forward


But it is the opposite. That command will enable the forwarding.
To disable it you must write:

# echo 0 > /proc/sys/net/ipv4/ip_forward