This is the question about command-line iptables syntax.
I have the following chains in /etc/sysconfig/iptables
# Generated by iptables-save v1.4.21 on Fri May 22 07:51:03 2015
*nat
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
COMMIT
but I need them to write to bash CSFPRE.SH for CSF firewall, so they should be in a command-line like
iptables -t nat -I POSTROUTING -s 192.168.254.0/24 -o br0 -j SNAT --to-source 69.64.56.847
or
iptables -A FORWARD -s 192.168.254.0/24 -m state --state NEW -j ACCEPT
But with the lines above I have a stumbling block.
I already tried something like
iptables :PREROUTING ACCEPT [0:0]
iptables -t nat -I :PREROUTING ACCEPT [0:0]
but no success.
iptables -P PREROUTING ACCEPT
says
iptables: Bad built-in chain name.
So still not a solution. Thanks in advance for any hint else to try
After some tests my solution was
iptables -t nat -P PREROUTING ACCEPT
iptables -t nat -P POSTROUTING ACCEPT
Related
We are using Suse Linux Enterprise Server 12. We need to block concurrent IP Addresses which is hitting our web server for more thatn 50 times per second and block that ip address for 10 minutes. Also it should distinguish attacker and genuine traffic and block attacker's IP forever. We have currently blocked using iptables , below is the rule.
iptables -I INPUT -p tcp --dport 443 -i eth0 -m state --state NEW -m recent --set
iptables -I INPUT -p tcp --dport 443 -i eth0 -m state --state NEW -m recent --update --seconds 1 --hitcount 50 -j DROP
It will just block the IPAddress which exceeds 50 connections but wont blacklist the IPAddress. Please let us know if we have a script that will match all the scenarios which is metioned above. Please Help.
I tested this and it works really nice. If the behavior is detected, the IP is put into hold-down for 10 minutes and logged. You can verify it's operation by watching these files. /proc/net/xt_recent/NICE, /proc/net/xt_recent/NAUGHTY. You need to build a script to parse the log for bad IP's and commit them to a file that is loaded into iptables on startup if you want to blacklist permanently. That concept is already clear so no need for me to include it.
#flush and clear
iptables -F -t nat
iptables -F
iptables -X
#this is where naughty kids go
iptables -N GETCAUGHT
#you got added to the naughty list
iptables -A GETCAUGHT -m recent --name NAUGHTY --set #everyone here is bad
iptables -A GETCAUGHT -j LOG --log-prefix "iwasbad: " --log-level 4 #and it goes on your permanent record
#if you are on the NAUGHTY list you get a lump of coal
iptables -A INPUT -i eth0 -m recent --name NAUGHTY --rcheck --seconds 600 -j DROP #check everyone at the door
#though everyone starts out on the NICE list
iptables -A INPUT -i eth0 -p tcp --dport 443 -m conntrack --ctstate NEW -m recent --name NICE --set #you seem nice
#but if you GETCAUGHT doing this you are naughty
iptables -A INPUT -i eth0 -p tcp --dport 443 -m conntrack --ctstate NEW -m recent --name NICE --seconds 1 --hitcount 50 --update -j GETCAUGHT #that wasn't nice
I used Amazon Lightsail to deploy a wordpress site and it worked like a charm. Now I have the need to restrict the IP addresses that can access on port 80 to the ones associated to the Firewall from SiteLock, and I am looking for the best and cleanest solution.
It looks like in Lightsail simplified version of the world, I can only open a port for public access, or close it.
My only idea now is logging in via SSH and use iptables, but I wanted to understand if that's the only way I can do this, or there is something "smarter".
This is what I came out with, that actually works, but uses iptables which I am not sure is the best option, so the question is still open to get a better solution.
Since SiteLock website says these IP ranges are to be allowed in:
SiteLock Firewall IP Ranges
199.83.128.0/21
198.143.32.0/19
149.126.72.0/21
103.28.248.0/22
45.64.64.0/22
185.11.124.0/22
192.230.64.0/18
107.154.0.0/16
2a02:e980::/29
I created a script to allow them all, and then close all the rest with an explicit DROP rule
sudo iptables -A INPUT -p tcp -s 199.83.128.0/21 --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
sudo iptables -A INPUT -p tcp -s 198.143.32.0/19 --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
sudo iptables -A INPUT -p tcp -s 149.126.72.0/21 --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
sudo iptables -A INPUT -p tcp -s 103.28.248.0/22 --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
sudo iptables -A INPUT -p tcp -s 45.64.64.0/22 --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
sudo iptables -A INPUT -p tcp -s 185.11.124.0/22 --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
sudo iptables -A INPUT -p tcp -s 192.230.64.0/18 --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
sudo iptables -A INPUT -p tcp -s 107.154.0.0/16 --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
sudo iptables -A INPUT -p tcp -s 2a02:e980::/29 --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
sudo iptables -A INPUT -p tcp -s 0.0.0.0/0 --dport 80 -j DROP
now, IPs can be whitelisted from AWS console itself. Go to your Lightsail instance in console, then networking. there you can choose ports to open, and to whitelist IP, check Restrict to IP. then enter whielisted IP or range and save.
reference: https://lightsail.aws.amazon.com/ls/docs/en_us/articles/amazon-lightsail-editing-firewall-rules
I have a transparent proxy.
I want to redirect a rdp connection to local process, but from 3rd packet. that means I want to pass first and second packet and from 3rd packet until end redirect packets to local process.
I use code below to configure my tproxy.
But it does not work and no packets pass and no packets go to local process(50082).
Could you please help me? I don't know my mistake.
${ip} rule add fwmark 1 lookup 100
${ip} route add local 0.0.0.0/0 dev lo table 100
${iptables} -t mangle -N DIVERT
${iptables} -t mangle -A PREROUTING -p tcp -m socket -j DIVERT
${iptables} -t mangle -A DIVERT -j MARK --set-mark 1
${iptables} -t mangle -A DIVERT -j ACCEPT
${iptables} -t mangle -A PREROUTING -p tcp --dport 3389 -m connbytes --connbytes 3: --connbytes-dir both --connbytes-mode packets -j TPROXY --tproxy-mark 0x1/0x1 --on-port 50082
${iptables} -t mangle -A PREROUTING -p tcp --dport 3389 -m connbytes --connbytes 1:3 --connbytes-dir both --connbytes-mode packets -j ACCEPT
I'm new to bash script and I need to make a script that runs the following commands:
service apache2 start
airmon-ng start wlan0
airbase-ng -e FREEINTERNET -c 1 -P wlan0mon
ifconfig at0 192.168.1.129 netmask 255.255.255.128
route add -net 192.168.1.128 netmask 255.255.255.128 gw 192.168.1.129
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables --table nat --append POSTROUTING --out-interface wlan1 -j MASQUERADE
iptables --append FORWARD --in-interface at0 -j ACCEPT
iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination 192.168.0.4:80
iptables -t nat -A PREROUTING -p tcp --destination-port 443 -j REDIRECT --to-port 80
iptables -t nat -A POSTROUTING -j MASQUERADE
dhcpd -cf /etc/dhcpd.conf -pf /var/run/dhcpd.pid at0
service isc-dhcp-server start
My big doubt is how to make the script open the airbase-ng -e FREEINTERNET -c 1 -P wlan0mon command in a different terminal and keep executing both airbase and the remaining commands. I’m using Kali 64-bit with GNOME.
You can run something in the background by suffixing it with &. If you want to run something in a new GNOME Terminal window, you can do so with gnome-terminal -e. Putting those together, to run your airbase-ng command in a new GNOME Terminal window while letting the rest of your script continue to run:
# …
airmon-ng start wlan0
gnome-terminal -e 'airbase-ng -e FREEINTERNET -c 1 -P wlan0mon' &
ifconfig at0 192.168.1.129 netmask 255.255.255.128
# …
Basically started with Squid and iptables today (google is your friend). This stuff is going to be the death of me.
I have Squid3 setup on Ubuntu 9.04 server as Transparent Proxy. It works sweetly when i use the proxy-box as my default gateway etc. The iptable rules for this setup was part of the tutorial. :P
I can unfortunately not access https sites (such as Gmail or anything on port 443 basically). This is because Squid dont like what it cannot cache, which in this case is the https traffic.
I would like to add an iptable rule so that i can basically access https sites and use Skype. Basically allow these types of traffic to pass through without going through Squid proxy? (bypassing it so to speak)
Would anyone perhaps know how to do this or have a link to any sources that would assist me in figuring it out?
Thank you.
After actually considering chewing through my own wrists and dreaming of IPs all night long + brute force googling/trying ANYTHING i could get my digital fingers on i managed to put something together that actually works. I dont know the technical reasons why, so if you can provide set explanations please do so! :D
PS: everything in the explanation is done via command line
PS: this is not a final solution, but its a working one in answer to my own question.
Here it is:
Step 1: Had to enable IP Forwarding on the box:
vim /etc/sysctl.conf
//find and uncomment the following
net.ipv4.ip_forward=1
net.ipv4.conf.all.rp_filter=1
Step 2: Add loop back rule (this is more for when all ports are covered, apparently many apps need it?
iptables -I INPUT -i lo -j ACCEPT
Step 3. Add rules for the bypassing of port 443: (eth1 is internet interface and x.x.x.x/eth0 is LAN interface)
iptables -t filter -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -t filter -A FORWARD -i eth0 -p tcp --dport 443 -j ACCEPT
iptables -t nat -A POSTROUTING -o eth1 -j SNAT --to-source x.x.x.x
Step 4. Then finally the rules making Squid transparent:(x.x.x.x is IP of LAN interface)
iptables -t nat -A PREROUTING -i eth0 -p tcp -m tcp --dport 80 -j DNAT --to-destination x.x.x.x:3128
iptables -t nat -A PREROUTING -i eth1 -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 3128
iptables -t nat -A POSTROUTING -o eth1 -j SNAT --to-source x.x.x.x
That is wrong. Means that every packet TCP/UDP/etc that you send from your intern LAN to Internet will use as SOURCE IP the Private LAN IP (probably 192.178.x.x), instead of the Public IP.
May be that helps you:
PREROUTING == DestinationNAT -> From Internet to Intern LAN
POSTROUTING == SourceNAT -> From Intern LAN to Internet
iptables -t nat -A PREROUTING -i intern -p tcp --dport 80 -j REDIRECT --to-ports 3128
iptables -A INPUT -j ACCEPT -m state --state NEW,ESTABLISHED,RELATED -i intern -p tcp --dport 3128
iptables -A OUTPUT -j ACCEPT -m state --state NEW,ESTABLISHED,RELATED -o extern -p tcp --dport 80
iptables -A INPUT -j ACCEPT -m state --state ESTABLISHED,RELATED -i extern -p tcp --sport 80
iptables -A OUTPUT -j ACCEPT -m --state ESTABLISHED,RELATED -o intern -p tcp --sport 80
To bypasss 443 would be enough with:
iptables -I FORWARD -p tcp --dport 443 -j ACCEPT
And if your system/squid/firewall is also the router from your network to internet, do not forget:
iptables -t nat -A POSTROUTING -o extern -j SNAT --to-source Public_external_IP
For those explanations...
step #1 sets up the machine as a router. This is required for any Linux machine that is going to accept or forward IP traffic destined for machines other than itself. Without this the lowest levels of the networking stack will reject the traffic and NAT will not even get a chance to do its thing.
step #2 is not relevant to the problem being asked about. It may or may not be needed for the router operations unrelated to the proxying.
step #3 lets the machine relay port 443 normally as a router. The POSTROUTING rule could be made better by using MASQUERADE instead of SNAT.
step #4 both lines do the same thing in different ways. The first line may lead you to trouble in future if you dont know what the differences are between DNAT and REDIRECT. For simplicity use REDIRECT only.
Reading http://wiki.squid-cache.org/ConfigExamples/Intercept/LinuxRedirect could have saved you a lot of trouble.
There is also a critical mangle table rule missing from your setup which is explained on that wiki page.