iptables

How to do the port forwarding from one ip to another ip in same network?

These rules should work, assuming that iptables is running on server 192.168.12.87 : #!/bin/sh echo 1 > /proc/sys/net/ipv4/ip_forward iptables -F iptables -t nat -F iptables -X iptables -t nat -A PREROUTING -p tcp –dport 80 -j DNAT –to-destination 192.168.12.77:80 iptables -t nat -A POSTROUTING -p tcp -d 192.168.12.77 –dport 80 -j SNAT –to-source 192.168.12.87 You … Read more

IPTABLES – Limit rate of a specific incoming IP

IPTables isn’t made for this kind of work, where lots and lots of packets need to be analyzed to make these decisions. IPTables is partly the answer though! The real answer to this is the awesome and underused traffic control facilities in Linux. Note that mucking around with this without knowing what is going on … Read more

How to start/stop iptables on Ubuntu?

I don’t know about “Ubuntu”, but in Linux generally, “iptables” isn’t a service – it’s a command to manipulate the netfilter kernel firewall. You can “disable” (or stop) the firewall by setting the default policies on all standard chains to “ACCEPT”, and flushing the rules. iptables -P INPUT ACCEPT iptables -P OUTPUT ACCEPT iptables -P … Read more

REJECT vs DROP when using iptables

As a general rule, use REJECT when you want the other end to know the port is unreachable’ use DROP for connections to hosts you don’t want people to see. Usually, all rules for connections inside your LAN should use REJECT. For the Internet, With the exception of ident on certain servers, connections from the … Read more

How can I port forward with iptables?

First of all – you should check if forwarding is allowed at all: cat /proc/sys/net/ipv4/conf/ppp0/forwarding cat /proc/sys/net/ipv4/conf/eth0/forwarding If both returns 1 it’s ok. If not do the following: echo ‘1’ | sudo tee /proc/sys/net/ipv4/conf/ppp0/forwarding echo ‘1’ | sudo tee /proc/sys/net/ipv4/conf/eth0/forwarding Second thing – DNAT could be applied on nat table only. So, your rule should … Read more

best way to clear all iptables rules

To answer your question succinctly, no: there would not be any “leftover” rules after flushing every table. In the interest of being thorough however, you may want to set the policy for the built-in INPUT and FORWARD chains to ACCEPT, as well: iptables -P INPUT ACCEPT iptables -P FORWARD ACCEPT iptables -P OUTPUT ACCEPT iptables … Read more

How to Unban an IP properly with Fail2Ban

With Fail2Ban before v0.8.8: fail2ban-client get YOURJAILNAMEHERE actionunban IPADDRESSHERE With Fail2Ban v0.8.8 and later: fail2ban-client set YOURJAILNAMEHERE unbanip IPADDRESSHERE The hard part is finding the right jail: Use iptables -L -n to find the rule name… …then use fail2ban-client status | grep “Jail list” | sed -E ‘s/^[^:]+:[ \t]+//’ | sed ‘s/,//g’ to get the … Read more