iptables Linux的 Firewall (testing)

My iptables 設定,
OS: Ubuntu 10.04 LTS
iptables version: 1.4.4
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# Loopback is totally open
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT
# Log and block IP spoof from outside
iptables -A INPUT -s 255.0.0.0/8 -j LOG --log-prefix "spoofed source ip"
iptables -A INPUT -s 255.0.0.0/8 -j DROP
iptables -A INPUT -s 0.0.0.0/8 -j LOG --log-prefix "spoofed source ip"
iptables -A INPUT -s 0.0.0.0/8 -j DROP
iptables -A INPUT -s 10.0.0.0/8 -j LOG --log-prefix "spoofed source ip"
iptables -A INPUT -s 10.0.0.0/8 -j DROP

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# iptables --help
Usage: iptables -[AD] chain rule-specification [options]
       iptables -I chain [rulenum] rule-specification [options]
       iptables -R chain rulenum rule-specification [options]
       iptables -D chain rulenum [options]
       iptables -[LS] [chain [rulenum]] [options]
       iptables -[FZ] [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 [rulenum]]
List the rules in a chain or all chains
  --list-rules -S [chain [rulenum]]
Print 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.