This patch adds CONFIG_IP_NF_MATCH_STRING which allows you toĪnd iptables 1.2.5, wich I haven't compiled yet, so cannot tell for sure, has something that seems to be awesome. percent will match randomly packets with a probability of 'percent' Which allow you to match packets randomly This option adds CONFIG_IP_NF_MATCH_RANDOM, Iptables -p tcp -syn -dport 80 -m iplimit -iplimit-above 16 -iplimit-mask 24 -j REJECT # limit the nr of parallel http requests to 16 per class C sized
Iptables -p tcp -syn -dport 23 -m iplimit ! -iplimit-above 2 -j ACCEPT # you can also match the other way around: Iptables -p tcp -syn -dport 23 -m iplimit -iplimit-above 2 -j REJECT # allow 2 telnet connections per client host Number of parallel TCP connections to a server per client IP address This adds CONFIG_IP_NF_MATCH_IPLIMIT match allows you to restrict the To set the TTL value of an IP packet or to increment / decrement it This adds CONFIG_IP_NF_TARGET_TTL option, which enables the user Status: Stable, needs new checksum handling To the POSTROUTING chain to alter the source of outgoing connections, PREROUTING chain to alter the destination of incoming connections, It creates a static 1:1 mapping of the network address, This adds CONFIG_IP_NF_TARGET_NETMAP option, which provides a target for Then you can choose wich patches to apply.
#Iptables netmap example download
Just download iptables, uncompress it, and run 'make patch-o-matic', provided you have a source tree in /usr/src/linux. If you don't understand it, then you should not be administering a gateway of any kind!īesides standard iptables functions, you can easily patch your kernel and add extra features.
#Iptables netmap example manual
I think the manual page provides more than sufficient information to get you started. You can also redirect to a different port number, in the above example to redirect to 192.168.0.10 port 321 it would be:Īs for this being an FAQ, I am aware of no such references on IPTables, and it doesn't matter. Iptables -t nat -A PREROUTING -i -j DNAT -to-destination This says: in the network address translation table and the chain that deals with incoming data prior to routing, and if the data is coming in from the internet and wants to go to TCP port 21 (ftp), DNAT (destination network address translate) it to transparently make it go to 192.168.0.10 Iptables -t nat -A PREROUTING -i eth1 -p tcp -dport 21 -j DNAT -to-destination 192.168.0.10 We use the PREROUTING chain in the NAT table: We want to redirect port 21 (FTP) to the machine 192.168.0.10įirst of all, we need to add a rule matching incoming data to port 21. OK here's an example: our gateway is 192.168.0.1 with lan interface eth0 and internet interface eth1. Yeah it's not as obvious as first, but it's actually pretty simple. Took me a while to figure out, too, and you have to decide which model is best for your network.Įither way, you basically need to write at least SOME code, so this is not for the faint of heart!
In either case, you have to queue packets to userspace by using the appropriate kernel module (ip_queue, IIRC), and a QUEUE target in your iptables rules. Shouldn't be more than 100 lines or so (at most). Plus, you'd need to write the daemon software. easy if you have login scripts set up from a centralized server, but a pain in the ass if you don't. The daemon method is more-or-less foolproof, but you need to deploy all the daemons. The 'nbtstat' method has a few disadvantages, including the fact that if a user logs onto two stations at once, only the most recently logged-on station will return a user name, and also that the returned ID codes (0x03) are the same for machine name and username. Well, there's two ways, each with their disadvantages: You can either use a modified 'nbtstat' (from Samba), or you can have a 'finger'-style daemon running on all the machines.
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