I was playing around with iptables to setup an isolated system. On a SLES10 system, I ran the below to setup my first draft of rules. I noticed that the rules come into effect immediately and do not require any restart of iptables.
Now, I want to add a new rule in the middle (lets say, open outbound communication on port 500 for ip yy.yy.yy.yy). But since the rules are evaluated sequentially, it will become effective after my last rule (which is iptables -P OUTPUT DROP). Since all packets match this default rule for output, I cannot add a new rule without rebooting the machine.
I wanted to know if there is a way to introduce new rules without having to reboot a machine, ie introduce a rule above the 'iptables -P OUTPUT DROP'. Any help or leads into documentation will help.
First, you can set the default policy anywhere you want, since it's not a rule. I myself always set the default policy right at the beginning of my firewall scripts.
Second, take a look at the man page for iptables. Using iptables -I you can insert rules at any position.
>> First, you can set the default policy anywhere you want, since it's not a rule.
I want to open specific ports at the output and block the rest. Putting the default output blocking policy would make the machine unusable. Thus, I shifted it to the bottom the firewall script and that worked. Anything I am doing wrong here?
>> Second, take a look at the man page for iptables.
I want to open specific ports at the output and block the rest. Putting the default output blocking policy would make the machine unusable. Thus, I shifted it to the bottom the firewall script and that worked. Anything I am doing wrong here?
The default policy takes immediate effect when set, that's true. However, it only blocks you out if you enter the commands manually, which should be the exception, not the rule. When using a script you can set the default policy first, and then open the ports you need without interrupting any traffic.
Hi, I am relatively new to firewalls and netfilter. I have a Debian Stretch router box running dnsmasq, connected to a VPN. Occasionally dnsmasq polls all of the desired DNS servers to select the fastest. When it does this it responds to replies of the non-selected DNS servers with a icmp type... (0 Replies)
Hello,
I did 2 scripts. The second one is, I hope, more secure.
What do you think?
Basic connection (no server, no router, no DHCP and the Ipv6 is disabled)
#######script one
####################
iptables -F
iptables -X -t filter
iptables -P INPUT DROP
iptables -P FORWARD... (6 Replies)
Hi,
I've been struggling with this all morning and seem to have a blind spot on what the problem is. I'm trying to use iptables to block traffic on a little cluster of raspberry pi's but to allow ssh and ping traffic within it.
The cluster has a firewall server with a wifi card connecting to... (4 Replies)
Hello,
I have iptables service running on my CentOS5 server. It has approx 50 rules right now.
The problem I am facing now is as follows -
I have to define a new chain in the filter table, say DOS_RULES & add all rules in this chain starting from index number 15 in the filter table.
... (1 Reply)
Hi Champs
i am new in Iptables and trying to write rules for my Samba server.I took some help from internet, created one script and run from rc.local :
#Allow loopback
iptables -I INPUT -i lo -j ACCEPT
# Accept packets from Trusted network
iptables -A INPUT -s my-network/subnet -j... (0 Replies)
Hi Gurus,
I need to add Multicast Port = xyz
Multicast Address = 123.134.143 ( example) to my firewall rules. Can you please guide me with the lines I need to update my iptables files with. (0 Replies)
Could someone help me with writing rules for iptables?
I need a dos attacks protection for a game server.
port type udp
ports 27015:27030
interface: eth0
Accept all packets from all IPs
Chek if IP sent more than 50 packets per second
Drop all packets from this IP for 5 minutes
I would be... (0 Replies)
Please i need help in how to add/remove rules in timezone files under /usr/share/zoneinfo/ , cause i have tried many times to do this by adding rules in an time zone file then compile this file with zic tool and then link it to /etc/localtime but always the output doesn't match what i have made... (0 Replies)
Hi
I have small home network and I want to block some forums on web
When I use this
iptables -A INPUT -s forum -j DROP
rules is applied but when I restart some of PC rules are not present any more also I tried to save firewall settings
iptables-save > /root/dsl.fw
but how to... (2 Replies)