Ubuntu Security :: How To Create An Iptable Rule
Sep 1, 2011
I need help creating an iptable rule. The iptables are installed on my router. My router also connects to a "hide my a**" vpn account
at 79.142.65.5:443 The goal is to somehow force the traffic to go through the vpn, because what sometimes happens is, the vpn connection drops (for what ever reason) and my real ip becomes exposed. Basically, I want to block "myself" from accessing the Internet when not connected to the vpn because of privacy concerns.
Below is my iptables. It has the 3 default chains and it also has many custom user chains. I need to know what kind of a rule to add, What interface to apply it to (lo,tun0,br-lan,eth1) and the correct chain to insert into.For example, you could tell me something like:
Quote:
FORWARD chain, change rule 1 to
iptables -R FORWARD 1 -j zone_wan_MSSFIX -p tcp --destination-port 443 -i eth1
Obviously, That was just a guess, I need someone that knows iptables to help me.
Code:
Chain INPUT (Policy: ACCEPT)
Rule # Traffic Target Prot In Out Source Destination Options
Rule 1 72.95 KB DROP all * * 0.0.0.0/0 0.0.0.0/0 state INVALID
Rule 2 1.11 GB ACCEPT all * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
[code].....
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Dec 22, 2010
In my new Centos i am not able to add iptable rule. iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3128bash: iptables: command not foundI am getting this error. I use this rule to forward ports to squid.
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May 12, 2010
i'd like to know how many rule can manage iptable. I'm asking that because i'd to drop all traffric from my localnet to porn site. I've a database of porn site witch contain about 900 000 domains. I know there are solutions like squidguard. But for my linux box i'd to use iptable to prevent users access to porn site and other blacklist site.
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Oct 30, 2010
I have installed squid as my proxy server in ubuntu 10.04 standalone system..Why i have installed squid in standalone sytem is, my friends used to access my system to browse sites and download files..So i have installed squid to block porn sites and downloads..But they simply bypass the proxy by disabling it..I know there is some way to force all browsers to go through proxy using iptables..But how to acheive it..? Is the below command suits my need..?If not what modification should i do..?
Code:
sudo iptables -t nat -A OUTPUT -p tcp --dport 80 -j REDIRECT --to-port 3128
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Feb 23, 2010
I'm not an iptables expert. Anybody know how to create a rule/chain that will log info similar to what tcpdump -s0 would do?
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Mar 4, 2011
This is what I have currently running.
Code:
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT
iptables -A INPUT -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
[code]...
How do I add this to the ruleset, without doing the whole thing over again?
Code:
iptables -A OUTPUT -d 10.3.0.0/16 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
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Jun 15, 2010
I have samba running on 192.168.100.209 and I am trying to open samba ports only for hosts in 192.168.100.0/24 network.. I have added following rules to iptables. But still I am not able to connect from machines from 192.168.100.0/24 network
Code:
iptables -A INPUT -s 192.168.100.0/24 -p tcp --dport 139 -j ACCEPT
iptables -A INPUT -s 192.168.100.0/24 -p tcp --dport 445 -j ACCEPT
What's wrong with the above rules ?
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Jun 13, 2010
i have the following system in my lan.
firewall(iptables)
etho(private) - 192.168.2.1
eth1(public) -189.117.57.2
squid server at 192.168.2.10
my request is that i have to make all out bound internet connection should go from proxy server , not directly to firewall. Please specify a iptable rule for blocking direct internet access. my clients ip ranges from 192.168.2.20 to 192.168.2.47
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Mar 10, 2011
tell me the command for iptable rule to add in Chain RH-Firewall-1 to block ftp port & the ftp server was configured in public ip address,i searched in google but i did'nt get the exact command for iptables rule in Chain RH-Firewall-1.
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Jul 16, 2010
Question (and Google results aren't making this clear): Ubuntu has both iptables & ip6tables installed. 1. If I set a rule in iptables, does that rule also apply to ipv6, or just ipv4?
2. If "no" to above, then it would be prudent to *also* set ip6tables rules as well if I want to maintain an active firewall, correct?
3. Does ip6tables rules have the same syntax and behavior (more or less) to iptables rules - i.e. can I just copy my iptables rules & change "iptables" to "ip6tables"?
4. Any gotchas or issues that I should be aware of?
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Apr 11, 2010
I have problems with iptables :
[root@server7 ~]# iptables -I INPUT -p tcp --syn -m recent --set
[root@server7 ~]# iptables -I INPUT -p tcp --syn -m recent --update --seconds 10 --hitcount 30 -j DROP
iptables: Unknown error 18446744073709551615
[root@server7 ~]#
I need stopping a SYN ddos attack... but iptable rule don't work...
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Apr 21, 2010
I'll like to mark all packet coming from and going to an ip adresse. And I'd like to match that mark packet in an other rule. Ex :
Rule 1 : Mark all packet coming from 192.168.2.0/25 with number 1
Rule 2 : Drop all packets which has been mark with number 1
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Jul 19, 2010
Currently I'm looking into implementing mod_security on all our apache servers. The installation on CentOS 5.5 comes directly with the "Core Rule Set" by the mod_security devs (curiously Debian and Ubuntu do not carry these) They also offer the Enhanced Rule Set for mod_security in a commercial package [URL] The main point there in their info link is the first point
Quote:
Tracking Credit Card Usage as required by the Payment Card Industry Data Security Standard However acc. to this wiki article ( http://en.wikipedia.org/wiki/Payment...urity_Standard ) that specific requirement isn't stated anywhere, as well as my colleague who's working on the PCI-DSS compliance for our code/servers/etc. mentioned that he hasn't heard of this specific requirement either. So my question would be if anyone has any experience with their ERS package and if it's needed for the PCI-DSS compliance compared to the requirements given in bullet points @ wiki article.
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Sep 12, 2010
I've configured iptables to act as a stateful firewall, but instead of simply rejecting packets I'd like to waste a potenial hackers time by droping any packet that would otherwise be returned. Are my rules sufficient or have I somehow opened myself up to an attacker by trying to write these rules myself?
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Jun 16, 2010
So I am new to ubuntu and am trying to work with "iptables". I have ubuntu version 10.04, in the terminal I try to create a new iptable by writing: iptables -N chain but the response is: FATAL: Error inserting ip_tables......... also it says "you must be root", what does root mean?
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Jan 27, 2011
I have a caching dns and SNMP ( MRTG ) both on the same server how can I permit dns and snmp traffic in INPUT chain?? I have tried the following:
iptables -A INPUT -p udp --sport 1024:65535 --dport 53 -j ACCEPT
iptables -A INPUT -p udp --sport 53 --dport 1024:65535 -j ACCEPT
iptables -A INPUT -p udp --sport 1024:65535 --dport 161:162 -j ACCEPT
iptables -A INPUT -p udp --sport 161:162 --dport 1024:65535 -j ACCEPT
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Feb 23, 2011
Is it possible to block a subdomain or a one lower level directory URL access from other hosts or network ? I have a site running on my server and i want to block the particular directory under the domain, with the exception of loopback access? I mean the directory must be accessible from loopback/localhost.
[url] on port 10016(expect loopback)
[url] on port 10016 (expect loopback)
Code:
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Nov 8, 2010
I have a server that is on a high port number, and people want it on port 80. For root exploit issues people say the server can not run as root. So to solve things I want to redirect port 80 to a high port number, say 12345 on the machine. This has been discussed all over the web, so I find I need to do this:
/sbin/iptables -t nat -A PREROUTING -p tcp -d 123.45.67.89 --dport 80 -j REDIRECT --to-ports 12345
/sbin/iptables-save > /etc/sysconfig/iptables
And I do this, an voila things work for the whole world. All machines in the world can see the server on port 80 on the machine.Except, on the machine itself. On the machine 123.45.67.89, I try to get to the server on 123.45.67.89:80, I get a can't connect error. On the machine if I try 123.45.67.89:12345 I can connect.What am I doing wrong here? I don't want localhost network really, I want the ip address and port, but I want the forwarding to work on the local machine. But it doesn't...
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Jun 22, 2011
I recently set up a ftp server in my house running a dyndns service so I can get to it from the outside. I called my isp to get some help in setting up the router to forward port 21 from the outside to that box, and in short we had some problems. Long story short, they ended up bypassing the router itself, and now the line running to the box is its own fixed external ip. Naturally I want a pretty darn good iptables setup for this. The box runs proftpd and so far my iptables only accepts local loopback and port-21. (I left port 80 closed as its only purpose is to be a standalone ftp server) But I know there must be a safer rule for port 21, as right now its just wide open. Anyone have any ideas on how to make this a bit safer? Also would that command be fine for any of the linux machines im connecting to it from the outside too?
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Jul 16, 2011
I don't know if FC15 has the iptable rules like the ones shown below by default or not but I wanted a second opinion about the safety they provide. Why is icmp accepted (INPUT rule 1) from/to all ip? and is it better to remove this rule? When the protocol is all (INPUT rule 2), does it mean from ip layer and above?? and is it required/safe to have this rule? The 3rd rule is to allow tcp-port 22 connections (ssh) to/from all ip. I think this is correctly set and required. The 4th rule in INPUT table rejects pings with the icmp-host-prohibited message; which I don't think is the best solution. Instead it can be set to silently drop icmp packets. Then, the FORWARD table uses reject instead of silent drop for forwarding icmp ping packets.
Code:
what do you think about the new rules and their order?
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Feb 22, 2011
I'm trying to set up a firewall at the moment that allows access to my custom SSH port from only my friend's url (they have a static url but dynamic IP). I find iptables a bit of a nightmare and was hoping to use UFW for most of my day to day firewall maintenance and just make a few extra iptable rules to cover exceptional circumstances like this. Fortunately it seems UFW allows this with /etc/ufw/before.rules and /etc/ufw/after.rules. So at the moment I'm just trying to get the basic iptables rules right. As I say I'm not very good with iptables, does this look right?
Code:
## Drop Default SSH port access With Logging
iptables -N SSH_DEFAULT
iptables -A INPUT -p tcp --dport 22 -m state --state NEW -j SSH_DEFAULT
[code].....
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Feb 4, 2011
I see on my webserver some logs as follows Quote:
203.252.157.98 - :25:02 "GET //phpmyadmin/ HTTP/1.1" 404 393 "-" "Made by ZmEu @ WhiteHat Team - www.whitehat.ro"
203.252.157.98 - :25:03 "GET //phpMyAdmin/ HTTP/1.1" 404 394 "-" "Made by ZmEu @
[code]....
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Apr 20, 2010
Do I have to create a rule for:
Code:
$IPT -A fwalert -p tcp --tcp-flags SYN,ACK SYN,ACK -m conntrack --ctstate NEW $RLIMIT -j LOG $LOGLIMIT --log-tcp-options --log-level 4 --log-prefix
to drop rather than log if my table has a default policy of drop with :
Code:
$IPT -t fwalert -P DROP
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May 27, 2010
Quote:
-A RH-Firewall-1-INPUT -s 10.12.0.0/16 -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
Ex- 10.12.0.0/16, 172.150.0.0/16, 192.168.20.0/24
How can we add multiple sources network address in the above INPUT chain?
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Jan 24, 2010
I have a netbook (MSI Wind U100 rebrand) that has one of those card readers built into the handrest. The thing is I've never used it once, and it keeps popping up in powertop as waking the cpu when it should just shut up and be quiet.Aside from breaking open the case and tearing it out, the immediate solution is to browse to /sys/bus/usb/devices/usb1/1-6/ and pipe 1 to the file remove. That disables it until system reboot or resume, at which point I have to do it all over again.
Code:
$ echo 1 | sudo tee /sys/bus/usb/devices/usb1/1-6/remove
Now I'd like to create an udev rule to make it not get initialized at all. A quick Google search found me this article on creating udev rules, and after toying about with the udevadm tool I managed to produce the attributes/properties of the device.
Code:
zorael@lethe:/sys/bus/usb/devices/usb1/1-6$ udevadm info -a -p $(pwd)
Udevadm info starts with the device specified by the devpath and then walks up the chain of parent devices. It prints for every device found, all possible attributes in the udev rules key format. A rule to match, can be composed by the attributes of the device and the attributes from one single parent device.
looking at device '/bus/usb/devices/usb1/1-6':
KERNEL=="1-6"
SUBSYSTEM=="usb"
DRIVER=="usb"
ATTR{configuration}=="CARD READER
[code].....
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Jul 23, 2011
For example, can I write something to the effect: block all outbound UDP connections over port 53 except those going to IP 123.456.789. Or stated another way: Block outbound to port 53/udp NOT going to ip address 123.454.678Is it possible to do this? How would I write the argument?
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Dec 20, 2010
I guess this is the right place to put questions about iptables, so forgive me if it is not.I have a MySQL database which I need to allow connections to: 1 - the internal network; 2 - the web server (Apache) connections;3 - A user who is out of this network in a range of dynamic IP.Let's suppose the range IP for this user is 179.4.247.0-179.4.247.254 and the server; where is MySQl and Apache is 60.22.30.232. This user will use the windows client MySQL tool to make connections into this database.
So I think these rule below allow connections to the internal network and apache:
iptables -A INPUT -i eth0 -m state state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -i eth1 -m state state ESTABLISHED,RELATED -j ACCEPT
[code]....
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Apr 25, 2016
I'm trying to configure auditd to monitor "strange" events with apache2 weberver on Wheezy (though same problem occurs on Jessie), tried both with "vanilla" 3.2 and backports 3.16 kernel I am actually using.
Here's auditd rules I have problem with:
Code: Select all-a exit,never -F arch=b64 -S stat -F path=/var/www/server-status -k web
-a exit,always -F arch=b64 -S stat -F uid=www-data -F success=0 -k web
So to recap, I want to log stat syscall failures for www-data user, but excluding some "known" issues, such as that "/var/www/server-status" (after a2enmod status, /server-status path can be accessed for statistics, though apache2 still tries to find physical file for that path and fails).
But the problem is.. excluding does not work.
Here's "auditctl -l" output:
Code: Select all# auditctl -l
LIST_RULES: exit,never arch=3221225534 (0xc000003e) watch=/var/www/server-status key=web syscall=stat
LIST_RULES: exit,always arch=3221225534 (0xc000003e) uid=33 (0x21) success=0 key=web syscall=stat
But when I execute:
Code: Select all# wget -O - http://localhost/server-status
audit.log appears:
Code: Select alltype=SYSCALL msg=audit(1461591557.077:365): arch=c000003e syscall=4 success=no exit=-2 a0=7f1bedab9358 a1=7ffef316ac20 a2=7ffef316ac20 a3=7f1bedab91f8 items=1 ppid=2398 pid=2451 auid=4294967295 uid=33 gid=33 euid=33 suid=33 fsuid=33 egid=33 sgid=33 fsgid=33 tty=(none) ses=4294967295 comm="apache2" exe="/usr/lib/apache2/mpm-prefork/apache2" key="web"
type=CWD msg=audit(1461591557.077:365): cwd="/"
type=PATH msg=audit(1461591557.077:365): item=0 name="/var/www/server-status" nametype=UNKNOWN
type=UNKNOWN[1327] msg=audit(1461591557.077:365): proctitle=2F7573722F7362696E2F61706163686532002D6B007374617274
So, syscall=4 (stat) is still captured. Looks like "path" is known for auditd, but not excluded.
I've tried various rule combinations, for example simpler, more generic one:
Code: Select all-a exit,never -F path=/var/www/server-status
But it's the same.
Sadly man audit.rules and man auditctl does not have "exit,never" examples, only some (sometimes also similarly unsuccessfull) google results.
Could it be that Debian kernel does not support some audit features?
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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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Nov 17, 2010
I'am using the explicit match 'quota' with iptables. I wonder how can I save quota between restart for every rule. All the quota resets at reboot.
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