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I want redirect all outgoing traffic with port 8080 to local port 8080
for example i create server with this command nc -l -p 8080 and i want when use this command nc 1.2.3.4 8080 , nc redirect and connect to 127.0.0.1:8080
i try with this command:
iptables -t nat -A POSTROUTING -p tcp --dport 80 -o eth0 -j SNAT --to-source IP
but not worked!
how to do it?
Local originated traffic isn't passing through nat/POSTROUTING chain. You should add rule like this:
iptables -t nat -A OUTPUT -p tcp --dport 8080 -j DNAT --to-destination 127.0.0.1:8080
Additional info:
http://upload.wikimedia.org/wikipedia/commons/3/37/Netfilter-packet-flow.svg
http://www.linuxtopia.org/Linux_Firewall_iptables/index.html Chapter 4.
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By the following commands, I forward the incoming traffic to the server to another IP
sudo sysctl net.ipv4.ip_forward=1
sudo iptables -t nat -A PREROUTING -p tcp --dport 22 -j DNAT --to-destination <ip1>
sudo iptables -t nat -A PREROUTING -j DNAT --to-destination <ip2>
sudo iptables -t nat -A POSTROUTING -j MASQUERADE
I want to create a limit on the ports, that is, only 2 connections can be connected on each port.
How can I do this?
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I inherited a complex iptables script acting as our gateway/router. It handles everything well, including NAT and harpin nat. It also does port forwarding. However, the port forwarding can't be specified by source IP. So if the port 25 is forwarded, every IP can connect to that port.
The FORWARD chain policy is ACCEPT. I tried to change it to DROP and built some rules. It seems that there are too much on specifying rules for every allow scenario.
What I am looking for is to specify things like this:
iptables -A FORWARD -p tcp -i $WAN_IFACE --dport 25 -s (!(1.1.1.1 and
1.1.1.2)) -j DROP
But iptables does not support and and or.
Is there any way to implement this?
You can create a new chain for all packets going to Port 25 and then do more specific filtering there:
iptables -N port25
iptables -A FORWARD -p tcp -i $WAN_IFACE --dport 25 -j port25
iptables -A port25 -s 1.1.1.1 -j ACCEPT
iptables -A port25 -s 1.1.1.2 -j ACCEPT
iptables -A port25 -j DROP
The creation of user-defined chains is the way to implement and and or rules.
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I am trying to figure out how to add a 1:1 NAT with IPTables but only on a single port, I know how to forward all traffic, but can't seem to find anything on a single port such as
192.168.1.1:21 -> 172.16.1.1:21
192.168.1.2:21 -> 172.16.1.2:21
192.168.1.3:21 -> 172.16.1.3:21
192.168.1.4:21 -> 172.16.1.4:21
I cant do this by say allowing only one port because there are other applications also doing traffic redirections on other ports.
All I have so far is something like this, but it doesn't specify the IP it originally landed on as a parameter.
sysctl net.ipv4.ip_forward=1
iptables -t nat -A PREROUTING -p tcp --dport port -j DNAT --to-destination ip:port
iptables -t nat -A POSTROUTING -j MASQUERADE
Use the -d flag to specify original destination.
iptables -t nat -A PREROUTING -d <external-ip> -p tcp --dport port -j DNAT --to-destination <internal-ip>:port
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How to deny access to port 80 of the server to everyone except ip 192.168.0.36?
What I do wrong:
iptables -A INPUT -p tcp —dport 80 ! -s 192.168.0.36 -j DROP
Bad argument —dport =(
You may try like this:-
iptables -A INPUT -p tcp --dport 80 -s 192.168.0.36 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
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Closed 10 years ago.
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I have multiple IP addresses on the same server and I would like to redirect all outgoing traffic on port 80 to a different IP on the same server just no to use always main IP.
Currently I'm using this:
/sbin/iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to-source IP;
and it works well, but it redirects everything and when I make backups over SSH backup it's failing.
System: CentOS 5.8 64-bit
This worked:
iptables -t nat -A POSTROUTING -p tcp --dport 80 -o eth0 -j SNAT --to-source IP