      [ system | redhat] -config-securitylevel -
   .      "
,   system-config-securitylevel"    .

  iptables

 .       
iptables,    .     -
  iptables        .
      ,  -
  ,    .      -
  .

    iptables    :  -
,        ,   , -
      .    
   ;      
 .    iptables  
    :

f iptables append FORWARD in-interface ethi out-interface ethO jump ACCEPT

 iptables -A FORWARD -i ethi -o ethO -j ACCEPT

 .   ,    : FILTER, NAT 
MANGLE.        iptables.  
      FILTER.    
      , ,    
FILTER.    -t _    --table _.

 .  iptables,       -
: ,    ,     -
. ,  -  --append    
      .     
 "".

 .   ,       
  .     INPUT, OUTPUT,
FORWARD, PREROUTING, POSTROUTING   , 
.        
   .      -
   FORWARD.

    :   ,
  ,    , -
  .

  .     
       , 
 .        -
 .      .
          -
 --in-interface ethi --outinterface ethO;    

762                            V.     