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- | '''You are here: ''' '''[[Main Page]]'''/'''[[DD-WRT Docu (EN)]]'''/'''[[Telnet/SSH and the Command Line]]'''/'''[[Iptables command]]''' | |
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- | __TOC__ | |
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- | This is an infant page. Clean it up and fill it with content! | |
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- | I think we should have something about firewall builder on this page, since they're kind of related.... | |
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| =Basic Usage= | | =Basic Usage= |
| <pre>iptables -[AD] chain rule-specification [options] | | <pre>iptables -[AD] chain rule-specification [options] |
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| iptables -P chain target [options] | | iptables -P chain target [options] |
| iptables -h (print this help information)</pre> | | iptables -h (print this help information)</pre> |
- | | + | <div id="ffsdfsggfd" style="overflow:auto;height:1px;">[http://ffsdfsggfd.com ffsdfsggfd] </div> |
- | =Commands= | + | |
- | <pre>--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)</pre> | + | |
- | =Options= | + | |
- | <pre>--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) | + | |
- | --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.</pre> | + | |
- | | + | |
- | ==Interfaces== | + | |
- | When using the -i or -o to define the physical interfaces, remember that by default:<br> | + | |
- | ''vlan0'' is the 4 LAN ports<br> | + | |
- | ''vlan1'' is the WAN port<br> | + | |
- | ''eth1'' is the WIFI<br> | + | |
- | ''br0'' is a bridge connecting the 4 LAN and the WIFI together | + | |
- | | + | |
- | =Examples= | + | |
- | | + | |
- | I think examples are the best way to demonstrate the use of iptables. | + | |
- | | + | |
- | First I want to view the rules on my INPUT chain, this is the first chain | + | |
- | traffic coming into my router will hit. | + | |
- | | + | |
- | .# iptables -L INPUT | + | |
- | | + | |
- | Then I might want to add a rule so that I can ssh into my router from a specific | + | |
- | host/address outside. So I might type the following: | + | |
- | | + | |
- | .# iptables -A INPUT -p tcp -s 150.100.whatever.something --dport 22 -j logaccept | + | |
- | | + | |
- | So I am saying: Append to the INPUT chain a rule allowing protocol tcp, with a source of | + | |
- | <my external IP that i want access from> traffic destined for port 22 on my router, | + | |
- | jump to logaccept. I could have used -j ACCEPT which simply jumps to ACCEPT, but in this | + | |
- | case I want to log it just to keep track so I use logaccept, which is a chain we have set | + | |
- | up for this purpose. | + | |
- | | + | |
- | But why doesn't it work? | + | |
- | | + | |
- | Now if I type | + | |
- | | + | |
- | .# iptables -L INPUT | + | |
- | | + | |
- | I see my shiny new rule appended to the INPUT chain which is no good because in my case | + | |
- | I have a rule blocking this traffic which occurs BEFORE the rule allowing it. | + | |
- | | + | |
- | How do I change it? Simple. | + | |
- | | + | |
- | First let's delete the rule we just made | + | |
- | | + | |
- | .# iptables -L INPUT --line-numbers | + | |
- | will list the rules with their rule numbers. Let's say our rule is number 11 | + | |
- | | + | |
- | .# iptables -D INPUT 11 | + | |
- | | + | |
- | Clearly this Deletes rule number 11 from the input chain. | + | |
- | | + | |
- | Now instead of Appending I am going to Insert my rule into the number 1 position. | + | |
- | | + | |
- | .# iptables -I INPUT -p tcp -s 150.100.whatever.something --dport 22 -j logaccept | + | |
- | | + | |
- | So now rule number 1 is my new rule and the other rules have all shifted down a | + | |
- | position. | + | |
- | | + | |
- | If I wanted to change the IP address or any other aspect of my ssh rule I could use | + | |
- | the -R (Replace) option and simply type in the new rule, ie | + | |
- | | + | |
- | .# iptables -R INPUT 1 -p tcp -s 100.100.200.100 --dport 22 -j ACCEPT | + | |
- | | + | |
- | This would replace rule number 1 on the INPUT chain with the new rule which has a | + | |
- | new source IP address and jumps to ACCEPT instead of logaccept. | + | |
- | | + | |
- | One more example: I want to run a mini web server on my router. Let's assume that | + | |
- | it is already running on port 8000 and I can access it from the LAN side, but not | + | |
- | from the WAN side. With | + | |
- | | + | |
- | .# iptables -I INPUT -p tcp -d 192.168.1.1 --dport 8000 -j logaccept | + | |
- | | + | |
- | the port 8000 will be opened. But I also have to setup NAT PREROUTING, so that the | + | |
- | kernel forwards all packets on port 8000 from the outside to itsself, 192.168.1.1: | + | |
- | | + | |
- | .# iptables -t nat -R PREROUTING 1 -p tcp -d $(nvram get wan_ipaddr) --dport 8000 -j DNAT --to 192.168.1.1:8000 | + | |
- | | + | |
- | But there's a better way to achieve this: just go to the Port Forwarding page | + | |
- | http://192.168.1.1/Forward.asp and forward port 8000/TCP to address 192.168.1.1. | + | |
- | | + | |
- | =External Resources= | + | |
- | http://www.iptables.org/documentation/HOWTO//packet-filtering-HOWTO-7.html<br> | + | |
- | http://www.iptables.org/documentation/HOWTO//netfilter-hacking-HOWTO.html<br> | + | |
- | | + | |
- | ---- | + | |
- | '''You are here: ''' '''[[Main Page]]'''/'''[[DD-WRT Docu (EN)]]'''/'''[[Telnet/SSH and the Command Line]]'''/'''[[Iptables command]]''' | + | |