Security :: Setting Up IPTables For Kubuntu 10.4?
Feb 21, 2011
After discovering that the firewall was wide open I decided to finally study the iptables docs and learn how to add rules. Now, I've not yet finished reading guides and documentation but I'd like some advice before I set the default policy on the input chain to deny. I have added a permissive rule for the loopback adapter so that programs that use it do not become mute suddenly. I will also use netstat to see what ports to open for each program that connects to the internet. I'm not that interested in what ports to open but how to find what ports to open.
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Jan 27, 2011
I am setting my firewall rules using the command iptables.My question is i wanna know what command i can use that list rule 2 and 3 for instance in my table?i want to create rule that: The host is administered using SSH, scp and sftp so allow incoming SSH traffic and securing remote file copying and transferring.
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May 26, 2011
can anyone advise the best practice of installing and setting the iptables on U 8.04 LTS? currently iptables is not installed nor as package nor included as kernel module.
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Apr 5, 2011
My firewall , wich is an Ubuntu server 10.10 , have 3 interfaces:
eth0(192.168.0.254):linked to the DMZ
eth1(192.168.1.254):linked to the LAN
eth3(212.217.0.1):linked to the Internet
-The DMZ have one web server with a static address (192.168.0.1).
-My LAN address range is (192.168.1.2-192.168.1.100) managed by a DHCP server in the same firwall machine.
There are some of the rules that I need to set up :
-Allow HTTP between the LAN and the internet
-Allow HTTP between the web server in the DMZ, and the internet.
Is there a way to tell the firewall , to redirect all incoming HTTP requests only to the web server in the DMZ ?
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Jun 30, 2010
I've read the instruction about setting up the iptables rules to filter all port except HTTP, SSH, FTP. I require first remove all default iptables rules and set default rules to all chains as DROP:
# Set default-deny policies for all three default chains
$IPTABLES -P INPUT DROP
$IPTABLES -P FORWARD DROP
$IPTABLES -P OUTPUT DROP
Then allow only some ports:
#Accept inbound packets that are part of previously-OK'ed sessions
$IPTABLES -A INPUT -j ACCEPT -m state --state ESTABLISHED,RELATED
# Accept inbound packets which initiate SSH sessions
$IPTABLES -A INPUT -p tcp -j ACCEPT --dport 22 -m state --state NEW
# Accept inbound packets which initiate FTP sessions
$IPTABLES -A INPUT -p tcp -j ACCEPT --dport 21 -m state --state NEW
# Accept inbound packets which initiate HTTP sessions
$IPTABLES -A INPUT -p tcp -j ACCEPT --dport 80 -m state --state NEW
# Log anything not accepted above $IPTABLES -A INPUT -j LOG --log-prefix "Dropped by default:"
But I hired a VPS from other country so the only mean I can manage it is via SSH. If I setup the default rule to DROP first, I afraid that I can no longer connect via SSH to tell iptables allow SSH
So my question is:
- Does the IP tables take effect immediately after I input a rule?
- Is there any mean to run this as a batch job (create a script and run all these rules one time).
- My VPS has a web control panel which have a terminal via web. Is this a native terminal or just a connection via port 80 or 22?
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Apr 14, 2011
I am having difficulties setting up Symmetric NAT through iptables and I hope you can help me with this issue. First things first: "A symmetric NAT is one where all requests from the same internal IP address and port, to a specific destination IP address and port, are mapped to the same external IP address and port.If the same host sends a packet with the same source address and port, but to a different destination, a different mapping is used. Furthermore, only the external host that receives a packet can send a UDP packet back to the internal host."
Need: I am working on a SIP application and SIP apps face a problem with NATed networks. STUN is a solution to such a problem and my SIP application has an embedded STUN client functionality. Scenario and Technical Details:
[Code]...
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Nov 30, 2010
I am having a little trouble setting up a NAT firewall using iptables. I have 1 PC dedicated to being the firewall running Ubuntu 10.04 LTS. There are 2 NICs in this PC. One NIC is connected to the modem & the other is hooked into my router, sharing the connection through to the other PC on my LAN. Thing is that I am having troubles setting this up using iptables. I have it sharing the connection, but can't seem to make it forward 2 ports through to my webserver on the LAN. I am also wanting to setup init.d to control iptables. I have been trying to google this, but haven't found anything useful to get this accomplished. I put the following into rc.local to make the forwarding work:
/sbin/iptables -F
/sbin/iptables -N block
/sbin/iptables -A block -m state --state ESTABLISHED,RELATED -j ACCEPT
/sbin/iptables -A block -m state --state NEW -i ! eth0 -j ACCEPT
/sbin/iptables -A block -j LOG
/sbin/iptables -A block -j DROP
/sbin/iptables -A INPUT -j block
/sbin/iptables --table nat -A POSTROUTING -o eth0 -j MASQUERADE
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Feb 21, 2011
I need to set OUTPUT to DROP, and add the outgoing traffic one by one, but I couldn't do it. My current config is as follows:
Code:
*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -j RH-Firewall-1-INPUT
-A FORWARD -j RH-Firewall-1-INPUT
:RH-Firewall-1-OUTPUT - [0:0]
-A INPUT -j RH-Firewall-1-OUTPUT
#previously ESTABLISHED,RELATED comm is ok
-A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
#80 is ok from all
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
If I change OUTPUT to DROP in :OUTPUT ACCEPT [0:0], I don't get any response from a server running in that box. I am using RHEL 5.5. Now, asking Red Hat is not an option: I have the license but I don't have support license.
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May 3, 2010
I'm intending to replace my current router (486DX2 w/16MB running FREESCO which has been faithfully working 24/7 for well over a decade) with a debian box with a bit more grunt and newer features. I'm currently setting up my iptables ruleset and am after a bit of advice re the FORWARD policy. A few example rulesets I have found set the default policy to DROP and the have two lines for each port forward, one to allow the traffic and one to direct the incoming packets to the correct machine.
iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 25 -j DNAT --to-destination 10.0.100.10:25
iptables -A FORWARD -i eth1 -p tcp --dport 25 -o eth0 -d 10.0.100.10 -m conntrack --ctstate NEW -j ACCEPT
I'm thinking of setting the default policy to ACCEPT to cut down on typing as my default INPUT policy is DROP and unless there is a valid FORWARD rule for a particular port, the packets aren't going anywhere anyway. Or have I misunderstood something. My googling returned heaps of example scripts & not much intelligent commentary. Alternatively, what do you all use to configure & maintain your debian gateways; hand rolled iptables rules, or any toolset recommendations?
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Mar 9, 2010
I've got a box with 2 interfaces, with IP1 = 192.168.100.1 and IP2 = 10.1.1.1 respectively on them. I've got an iptables rule that looks like:
Code:
iptables -t nat -A POSTROUTING -s 192.168.100.0/24 -d 10.0.0.0/8 -p udp -j SNAT --to-source 10.1.1.1 --random
If I get 2 consecutive packets from the same address and port from 192.168.100.0/24, they get SNAT-ed and come out of the same port on 10.1.1.1. If then I get another packet from the same address and port 10 minutes later, then it gets SNAT-ed, but comes out of a different port on 10.1.1.1. How can I set the time delay I would like iptables to remember its incoming address/port to outgoing port mappings?
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Jun 1, 2010
Im running a web server on port80, but i want traffic coming from ip 212.333.111.222 on port 80 to be fowarded to port 9020 on the same server that my web server is rinning at that is my sshd port
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Mar 9, 2010
I've got a box with 2 interfaces, with IP1 = 192.168.100.1 and IP2 = 10.1.1.1 respectively on them. I've got an iptables rule that looks like:
Code:
iptables -t nat -A POSTROUTING -s 192.168.100.0/24 -d 10.0.0.0/8 -p udp -j SNAT --to-source 10.1.1.1 --random
If I get 2 consecutive packets from the same address and port from 192.168.100.0/24, they get SNAT-ed and come out of the same port on 10.1.1.1. If then I get another packet from the same address and port 10 minutes later, then it gets SNAT-ed, but comes out of a different port on 10.1.1.1. My question is: how can I set the time delay I would like iptables to remember its incoming address/port to outgoing port mappings?
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Feb 1, 2009
I have been struggling with this for a very long time now. I have installed Fedora Core 9 on my computer. I have set it up as a caching-nameserver and this is working.
Then I wanted to secure my server with iptables, and I have so far made this script:
# Load the connection tracker kernel module
modprobe ip_conntrack
iptables -F
iptables -P INPUT DROP
iptables -P FORWARD DROP
[Code]....
I can reach the dns server with ping. When trying Nslookup it says that it got SERVFAIL from 127.0.0.1 trying next server, and then it times out.
My resolv.conf file lists:
nameserver 127.0.0.1
nameserver DNS-server
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Dec 14, 2009
Im pulling my hair out trying to get ftp to work through iptables.Im using vsftpd
Table: filter
Chain INPUT (policy DROP)
num target prot opt source destination
1 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
2 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
[code].....
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Feb 25, 2010
I have a problem with iptables, when I execute
[code]....
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Apr 4, 2010
I am trying to figure out how I can configure IPtables to only allow VNC traffic to an internal server over SSH.
My configuration is WAN < --- > Gateway (Ubuntu 9.10 Server) < --- > Internal Server (that I want to control with VNC over SSH)
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Dec 5, 2010
I am using Fedora on my desktop pc. I want to know how can i protact my PC from outside world. What firewall policy should i implement in iptables to keep it more secure.
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Jan 5, 2010
I'm following an openvpn installtion how to and it says to add this to the iptables:
Quote:
# External Interface for VPN
# VPN Interface
VPNIF="tun0"
VPNNET="172.16.0.0/24"
VPNIP="172.16.0.1"
### OpenVPN
[Code]....
Any thoughts as the whole formatting is separate and has the addition of FORWARD rules, etc. I need the VPN running on the .199 address
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Jun 3, 2010
i set up a dmz to have a internet web server and ftp server, and ssh only from local network, so i wrote a iptables script to load during boot :
[Code]...
The problem is that everything works fine ( i have the same rules for other services such as samba, nfs, mysql on another server) BUT ftp there is no way to make it work. not even locally.when i try to connect, i log in, but while listing the directory i get MLSD ... and it hangs like this for a moment, then i get error message "connection time out" , "impossible to list directory". if i turn off the iptables script no problem,ftp works fine.. but why all services work and ftp no?
how do i have to modify the rules? what is strange also is that if i set as OUTPUT policy "accept", the server seems to be offline."host unknown" error message. I was thinking the rule INPUT is fine cause at least i can login, but the dir list is not going out, so gotta modify output rules. or state?
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Mar 19, 2010
I've started a new job and have inherited a couple of RHEL4 64-bit servers. The firewall on them is currently disabled. I'm struggling to get them up and running as iptables is not the most user-friendly application. This lead me to downloading and trying a GUI front-end: Guarddog. Great app! But it doesn't have the default behavior I'm looking for. Here is what I need:
Default behavior: Firewall should be wide open, allowing ALL ports/IP's/TCP/UDP in and out of the server.
Blacklist: Oracle TCP port 1521 needs to be blocked in/out of the server.
This will help get us passed our company's security vulnerability scan. (We aren't able to patch/upgrade Oracle at this time because we'd lose vedor support with a legacy app). I will use these settings as a starting point, and then once I learn more and get more comfortable with iptables (or a GUI app) then I can fine tune things to make them more secure. As far as I know (correct me if I'm wrong) once I get a script I just copy it into /etc/rc.firewall and it will load when iptables starts.
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Mar 6, 2010
Is this how I would do that?
iptables -A INPUT -p tcp --destination-port 21 -d ! 168.192.1.2 -j DROP
This should block all incoming connections on port 21 from 192.168.1.2, correct? Thus preventing that IP from logging into my FTP.
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Feb 21, 2010
I'm using kubuntu-9.10-desktop-amd64.iso live (booted via grub2 loopback directly from iso on hd, in case that makes a difference). Processor is a E2180 which according to the Intel website supports the NX bit. I've enabled the option "Execute Bit Support" in the BIOS. /proc/cpuinfo shows both nx and pae in both flags lines. But dmesg says "Using x86 segment limits to approximate NX protection".
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Jan 10, 2011
I am trying to install a proxy on my Kubuntu 10.10, since I live in a country that blocks access to almost everything. I tried to install squid, anon, socks.. both with command-line and KPackageKit, but every time, I have this error message:
[code]...
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Mar 17, 2009
What i wanted to do was block everything from getting in my pc but still be able to surf the web and still use instant messenger.
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Jan 14, 2010
i ran this
Code:
iptables -N rate-limit
iptables -A rate-limit -p tcp -m conntrack --ctstate NEW -m limit --limit 3/min --limit-burst 3 -j RETURN
iptables -A rate-limit -j DROP
iptables -I INPUT 1 -p tcp --dport 22 -j rate-limit
i am no longer able to ssh in to the machine , how can i reset iptables and firestarted back to default?
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Jul 24, 2010
i need to open this address ftp.nai.com, is there a way to use address not ip in iptables?
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Sep 17, 2010
I've recently moved from Firestarter to UFW/GUFW, and I wonder if someone could confirm if my iptables configuration is secure.
When I enter sudo iptables -L i get:
Code:
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Dec 29, 2010
eth1 has connection to the net via gateway ..eth0 on the same machine has users on a intranet and needs access to the internet, i need to allow internet connection and prevent packets which logically originate from the internet getting into the intranet
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Apr 21, 2011
Installing a router, and I need to completely "wipe" iptables (flush I mean) on both computers, and I think I run ufw/gufw on both, so that would need to be uninstalled. The router is very secure, has NAT, etc, etc, and I'd rather setup all that side of things in one point, rather than on each computer.
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May 23, 2011
Can I have both ufw and iptables running together? My server is currently using ufw, if I add an iptables rule will it have any effect?
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