As you can image, we need iptables to block the ports we do not need to protect server.
But I need to request some third party resource, and I got confuse on how to do it.
Here are my iptables rules
iptables -F
iptables -A INPUT -p UDP -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -s 110.75.147.65/32 -j ACCEPT
iptables -A INPUT -s localhost -j ACCEPT
iptables -A INPUT -j DROP
And 110.75.147.65/32 is the one of third party servers' IP, I wonder if there are any way to allow all connection started by my server such as curl https://www.google.com/, otherwise I need to add all my third party servers' IP to the iptables rules.
How about
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
Related
After running this scripts
!/bin/bash
iptables -F
iptables -X
set default policy to drop
iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP
accept everything no matter port on localhost
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
allow input on port 22 (established connections auto accepted
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
allow traffic going to specified outbound ports
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -p tcp --dport 53 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 6667 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 6697 -j ACCEPT
drop anything that doesn't match the rules above
iptables -A INPUT -j DROP
iptables -A OUTPUT -j DROP
then when I typed on terminal yum -y update or anything when I using yum I got this messages
Loaded plugins: langpacks, product-id, rhui-lb, search-disabled-repos
Could not contact CDS load balancer southeastasia-cds2.cloudapp.net, tring others.
Could not contact CDS load balancer southeastasia-cds3.cloudapp.net, tring others.
Could not contact CDS load balancer southeastasia-cds1.cloudapp.net, tring others.
Could not contact any CDS load balancers: southeastasia-cds2.cloudapp.net, southeastasia-cds3.cloudapp.net, southeastasi
a-cds1.cloudapp.net, eastasia-cds4.cloudapp.net.
what are the ports for these load balancers for me to allow this in my firewall on redhat??
In my CentOS 6 i added a IPtables rules like DROP all the policy like
iptables -P INPUT DROP
Then I allow Port NO 22,80,443 with this command,
iptables -A INPUT -i eth0 -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --dport 22 -j ACCEPT
Now can access SSH with putty. But i can't access Internet. I have to know the exact problem of this.? Please help me.
Ofcourse you cannot access the Internet. You just added a rule that drops all incoming traffic (except for traffic coming in to ports 22, 80 and 443).
When you try to access the internet (if you're using a browser), your machine establishes a connection from
<local IP>:<port1> <----> <remote IP>:80
When the remote server responds to you, it will respond back to the same port1 that you sent the request from (which will NOT be 22, or 80, or 443. It will be a number usually higher than 32768), so it will get dropped by iptables.
Try these rules instead:
iptables -P INPUT DROP
iptables -I INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --dport 443 -j ACCEPT
The second rule tells IP tables to ACCEPT traffic that is coming to us, if it's coming to a port that we used to send outgoing traffic. This will allow you to see the response from the server, which you were dropping.
However, there's still a problem with DNS traffic, since it uses UDP not TCP. You can work around that by changing the first rule to:
iptables -P INPUT -p tcp DROP
so it only drops TCP traffic but not UDP traffic. There may be other ways to work around the DNS problem, depending on what exactly you want to do.
So your final ruleset should look like this:
iptables -P INPUT -p tcp DROP
iptables -I INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --dport 443 -j ACCEPT
I bought a domain on GoDaddy but developed the website using Node.js. So, I bought a VPS on VPSGet and deployed the server. I managed to link the domain name to the VPS IP address. However, since my node.js application is running a particular port number I needed to do port forwarding so that www.domain-name.com will redirect to the process and port on the VPS. I tried to configure my firewall as follows
*nat
:PREROUTING ACCEPT [0:0]
-A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 7497
COMMIT
*filter
# Allow all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0
-A INPUT -i lo -j ACCEPT
-A INPUT ! -i lo -d 127.0.0.0/8 -j REJECT
# Accept all established inbounds connections
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
# Allow all outbounds traffic
-A OUTPUT -j ACCEPT
# Allow HTTP and HTTPS connections from anywhere. Here, we use normal ports for http and ssl
-A INPUT -p tcp --dport 80 -j ACCEPT
-A INPUT -p tcp --dport 443 -j ACCEPT
# Allow http connections to node.js app
-A INPUT -p tcp --dport 7497 -j ACCEPT
-A INPUT -p tcp --dport 7525 -j ACCEPT
-A INPUT -p tcp --dport 2368 -j ACCEPT
# Allow forwarding to port 7497
-A FORWARD -p tcp -m tcp --dport 7497 -j ACCEPT
# Allow ports for testing
-A INPUT -p tcp --dport 8080:8099 -j ACCEPT
# Allow ports for mobile shell
-A INPUT -p tcp --dport 60000:61000 -j ACCEPT
# Allow ssh connections
-A INPUT -p tcp -m state --state NEW --dport 7112 -j ACCEPT
# Allow Ping
-A INPUT -p icmp -m icmp --icmp-type 8 -j ACCEPT
# Log iptables denied calls
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied:" --log-level 7
# Reject all other outbounds
-A INPUT -j REJECT
-A FORWARD -j REJECT
COMMIT
However, the redirection is not working. Could someone tell me what I am doing wrong? Please note that I am running a Ubuntu 12.04 on the VPS.
Thanks,
José
Have you tried to create the support request with detailed explanation to vpsget.com ?
Regarding to the wiki
http://wiki.vpsget.com/index.php/Forward_(redirect/nat)_traffic_with_iptables
you should use venet0 instead eth0
I am trying to create iptable rules that will allow incoming and outgoing ssh connections, and then allow outbound connections to specific ports, then finally drop anything that doesnt match.
These are the rules I have come up with, the SSH rules work, but when I tunnel into the box I cant seem to access http (port 80) even though i've allowed it. Can anyone spot the mistake?
#!/bin/bash
#clear iptables
iptables -F
iptables -X
#set default policy to drop
iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP
#accept everything no matter port on localhost
iptables -A INPUT -i lo -j ACCEPT
#allow established connections
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
#allow input on port 22, (established connections auto accepted)
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
#allow traffic going to specific outbound ports
iptables -A OUTPUT -p tcp --dport 80 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 443 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 6667 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 6697 -j ACCEPT
#...
#drop anything that doesnt match the rules above
iptables -A INPUT -j DROP
iptables -A OUTPUT -j DROP
Thanks for your time.
You might want to add the DNS ports, otherwise you may not be able to resolve any hostnames.
Allowing OUTPUT for TCP and UDP Port 53 should help.
You need to open port 80 for input and output with a rule like this:
iptables -A INPUT -i eth0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT
I have an application listening at port 27015. I want to allow all ips with client port 27005 and drop the rest. How do I go about this ?
This page shows some good examples of iptables.
http://www.cyberciti.biz/tips/linux-iptables-how-to-specify-a-range-of-ip-addresses-or-ports.html
So, something like this should do it:
iptables -A INPUT -p tcp --sport 27005 --dport 27015 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -j DROP
Little late but here is what I would do
iptables -A INPUT -p tcp --dport 27005 -j ACCEPT
iptables -A INPUT -j DROP
service iptables save
service iptables restart