#!/bin/sh
# 초기화
iptables -F
# 포트 스캔 방지
iptables -A INPUT -d 0.0.0.0/0 -p icmp -j DROP
# DoS 공격 방지
iptables -N syn-flood
iptables -A syn-flood -m limit --limit 12/second --limit-burst 24 -j RETURN
iptables -A syn-flood -j DROP
# ssh 정책(root, webpage 계정만 접속 가능)
# ssh 포트 : 22, root 번호: 0, webpage 번호:500
iptables -A INPUT -p tcp --dport 22 -m owner --uid-owner 0 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -m owner --gid-owner 0 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 22 -m owner --uid-owner 0 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 22 -m owner --gid-owner 0 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -m owner --uid-owner 500 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -m owner --gid-owner 500 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 22 -m owner --uid-owner 500 -j DROP
iptables -A OUTPUT -p tcp --dport 22 -m owner --gid-owner 500 -j DROP
# 1초에 15번 이상의 HTTP 접근을 할 경우 차단
iptables -A INPUT -m recent --name HTTP --rcheck --seconds 60 -j DROP
iptables -A INPUT -p tcp --dport 80 -m recent --update --seconds 1 --hitcount 15 --name HTTP -j DROP
#--------------------------------------------------------------------
# 커널 컴파일 및 iptables 패치 후, connlimit 사용이 가능한 경우
# 1초에 15번 이상의 HTTP 접근을 할 경우 차단
#iptables -A INPUT -p tcp --syn --dport 80 -m connlimit --connlimit-above 15 -connlimit-mask 24 -j DROP
#메일서버의 경우 동시에 5개이상 SMTP 접근일 경우 5분동안 접근 제한
#iptables -A INPUT -m recent --name spammer --rcheck --seconds 300 -j DROP
#iptables -A INPUT -p tcp --syn --dport 25 -m connlimit --connlimit-above 5 -m recent --name spammer --set -j DROP
#---------------------------------------------------------------------
#----------------------------------------------------------------------
# STRING 필터기능
# MSN 문자열이 들어간 패킷 차단
#iptables -A FORWARD -m string --string "messenger.msn.com" -j DROP
# 싸이월드 접속차단
#iptables -A FORWARD -p tcp --dport 80 -m string --string "Host: cyworld.nate.com" -j DROP
#----------------------------------------------------------------------
# 서버가 해킹당했을 때 DoS공격지로 사용될 경우에 적용.
# DNS 쿼리 이외 UDP 패킷 전송 방지
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A OUTPUT -p udp ! --dport 53 -m state --state NEW -j DROP
Usage: iptables -[AD] chain rule-specification [options]
iptables -[RI] chain rulenum rule-specification [options]
iptables -D chain rulenum [options]
iptables -[LFZ] [chain] [options]
iptables -[NX] chain
iptables -E old-chain-name new-chain-name
iptables -P chain target [options]
iptables -h (print this help information)
Commands:
Either long or short options are allowed.
--append -A chain Append to chain
--delete -D chain Delete matching rule from chain
--delete -D chain rulenum
Delete rule rulenum (1 = first) from chain
--insert -I chain [rulenum]
Insert in chain as rulenum (default 1=first)
--replace -R chain rulenum
Replace rule rulenum (1 = first) in chain
--list -L [chain] List the rules in a chain or all chains
--flush -F [chain] Delete all rules in chain or all chains
--zero -Z [chain] Zero counters in chain or all chains
--new -N chain Create a new user-defined chain
--delete-chain
-X [chain] Delete a user-defined chain
--policy -P chain target
Change policy on chain to target
--rename-chain
-E old-chain new-chain
Change chain name, (moving any references)
Options:
--proto -p [!] proto protocol: by number or name, eg. `tcp'
--source -s [!] address[/mask]
source specification
--destination -d [!] address[/mask]
destination specification
--in-interface -i [!] input name[+]
network interface name ([+] for wildcard)
--jump -j target
target for rule (may load target extension)
--goto -g chain
jump to chain with no return
--match -m match
extended match (may load extension)
--numeric -n numeric output of addresses and ports
--out-interface -o [!] output name[+]
network interface name ([+] for wildcard)
--table -t table table to manipulate (default: `filter')
--verbose -v verbose mode
--line-numbers print line numbers when listing
--exact -x expand numbers (display exact values)
[!] --fragment -f match second or further fragments only
--modprobe=<command> try to insert modules using this command
--set-counters PKTS BYTES set the counter during insert/append
[!] --version -V print package version.
