    : -i ethi - ethO.    -
 ,    ethi,   ethO.

  .     -
 .  iptables  ,   
    ,    . 
    .     
 ,       ,  
   ,   .   -
  1 (   )       
iptables -L --line-numbers.      , -
    ;      3  
INPUT ,      IP- 192.168.0.10.

# iptables delete -A FORWARD -i ethi - ethO -j ACCEPT
 iptables -R INPUT 3 -source 192.168.0.10 -jump REJECT

    ,     , -
      .    -
   -j   --jump .      
 ACCEPT    :--jump ACCEPT -j ACCEPT.

 .         . -
   (append)    INPUT,  -
 ,   TCP (--protocol tcp),  
    tcp_rules (jump tcp_rules).

# iptables --append INPUT --protocol tcp --jump tcp rules

     tcp rules, ,    
 ,      INPUT  , 
 ,     .

 .   ,    ;  
  ACCEPT  DROP  REJECT.   -
    FORWARD,   , 
 FTP- ( /etc/services,   iptables  -
  , ,  FTP   22).

# iptables --append FORWARD sport ftp jump REJECT

 ,  LOG,   :  -
     .   -
   ""    .

  

         
    iptables. ,     NAT
(      ):

# iptables -t NAT -F

 25. iptables:   763