iptables allow creation of rules to define packet filtering behavior.

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641 views

NAT with transparent proxy

is there a way to redirect all non local http requests that through my computer to use my transparent proxy, so i can log all websites are they visiting? and if possible all https requests too.. my ...
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Screen session running as root? (it shouldn't be) node.js

cd /serv screen -R node {in the screen} node test.js C^a d initially, ls -l /dev/pts total 0 crw--w---- 1 tick-tock tty 136, 0 2011-04-19 16:41 0 crw--w---- 1 tick-tock tty 136, ...
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1answer
2k views

multigateway routing for specific src port

I have two gateway to access internet, somehow I want to load balancing it, so far its working, but some connection or service need persistent gateway IP to be used, so the client should never change ...
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0answers
84 views

TC (Traffic Control) to control bandwidth

I'm having an issue with a bandwidth script that I've been using for a while to limit the outgoing bandwidth on a port. It worked fine at the beginning until I wanted to change the outgoing port ...
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0answers
20 views

Routing policy is not working

I have an Access Point with OpenWrt. On other host of the same LAN there is a squid (IP Address 192.168.80.148). I'd like to route packages with destination port 80 to 192.168.80.148. So I have root@...
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155 views

iptables and ip forwarding for failover

hi i have an ethernet nic interface with 4 additional virtual interfaces (failovers) all configured with public ip4 (IP-1 to IP-5) / netmask 255.255.255.255 / broadcast addr same as ip: eth0 -...
4
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1answer
66 views

Unable to get NAT working via iptables PREROUTING chain

So, not concerning ourselves with the WHY, and more so with the HOW, I'd like to see if anyone knows where I'm going wrong here. Basically, I'd like to forward all packets headed for port 80 on an IP ...
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390 views

iptables: using “conntrack” and “recent” modules to block unsolicited packets

When I only allow RELATED and ESTABLISHED packets, and DROP everything else, my firewall rules work perfectly and I have no problems: ### VARIANT A -A INPUT -i wlan0 -m conntrack --ctstate RELATED,...
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241 views

Is iptables able to filter off UNREPLIED connections?

I am a using dd-wrt router and trying to get some per-user metrics, I was wondering about filtering only ESTABLISHED connections or include NEW and RELATED, I have read a lot about this last two, but ...
4
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1answer
301 views

Route VPN traffic through different proxies

I want to setup VPN server and route (based on my routing algorithm) all traffic through different proxy servers. Let's say I have one host, with many users, connected to my VPN. I want to route all ...
4
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1answer
488 views

Dovecot/Postfix mail server replies to [SYN] with [RST, ACK] when user attempts to connect (POP3). Likely iptables?

Currently I'm trying to troubleshoot an e-mail server that will allow users to send e-mail, but not log in to the server (POP3) or receive e-mail using their Outlook clients. Previously this was ...
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463 views

iptables rule no actions on scapy packets

I wrote this rule to change all udp destination IP addresses to 8.8.8.8 when dport is 53: iptables -t nat -A OUTPUT -p udp -m udp --dport 53 -j DNAT --to-destination 8.8.8.8 The rule worked when ...
4
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1answer
70 views

Is there any difference between these two configuration options?

Is there any actual difference between iptables -P FORWARD DROP and net.ipv4.ip_forward = 0 ? I know that one is a firewall command while the other one is a kernel option. But: I don't know ...
4
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1answer
147 views

What are the requierements to sniff UDP packets in a Wireless Ad-Hoc network?

In a wireless Ad-Hoc network, I have two computers which communicates in UDP together from 192.168.1.3 to 192.168.1.5 I have a third computer (192.168.1.6) which wants to listen to the packets which ...
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0answers
562 views

Redirect all non-local traffic to a socks proxy

Is it possible to redirect all non-local traffic to a socks proxy? so, for example i have: 4 computers (clients A-D: 10.0.0.1-4 or dhcp) 1 computer with 2 network cards (gateway-server, eth0: 10.0....
4
votes
2answers
762 views

Policy routing with load balanced ppp connections

This my setup using Debian 6.0. 6. It's role is a proxy server and a load balancer using eight 3G modems. Whenever a ppp connection dials it takes over the default gateway which is ok but it also ...
4
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2answers
2k views

Iptables GEOIP not working under Debian Squeeze

I've just installed xtables-*, compiled the geoip database, but when I try to use an iptables command it always gives back the following error: Command iptables -I INPUT -p tcp --dport 80 -m geoip --...
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3answers
964 views

How to get all IPtables rules

I'm trying to see a list of all the rules in IPtables in a Debian 7 server. when I try: iptables -L -n I only get one rule (which I entered 5 minutes ago). I have many others, for port 80, mysql ...
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2answers
7k views

iptables log file

I have ubuntu and I want to know where can I find the log file of iptables? I find out /var/log/messages, but I am not sure this is a correct log file or not. And I also want to know when this log ...
3
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2answers
182 views

Why doesn't iptables receive the marked packet?

I was learning the ping command options. In that I found the -m option to set the mark for a packet. The below command sends the packet with marking of 10 to the 192.168.2.65. ping -m 10 192.168.2....
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2answers
799 views

Meaning of log entries from an iptables configuration

My router has Linux as its OS. The system log has a lot of rows about iptable and klogd that I don't understand, could someone explain them to me? The iptables setup: iptables -t nat -A PREROUTING -...
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3answers
62 views

IPtables installation question

I am new to installing iptables and have an excellent book called "Linux Firewalls: Attack Detection and Response" by Michael Rash. I have a few questions before I begin. I want to make an ...
3
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1answer
756 views

Which ports should I open for apt-get to work?

I installed Webmin, and then set up the firewall like this: INPUT SSH port ALLOWED Webmin port ALLOWED HTTP port (80) ALLOWED DROP EVERYTHING ELSE FORWARDING no rules OUTPUT no rules If I remove ...
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3answers
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What does this firewall record mean?

Running iptables -L -n gives me the following info: Chain IN_ZONE_work_allow (1 references) target prot opt source destination ACCEPT tcp -- 0.0.0.0/0 0.0....
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1answer
5k views

How to re-enable iptables on Fedora 18?

FirewallD is the default firewall in Fedora 18. I have been using iptables for quite some time and have a custom configuration which I need for logging of ip traffic. I am not used to the new ...
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2answers
3k views

How do I build the iptables kernel module for a loaded kernel?

I've built a kernel with loadable module support for various reasons, one of them the possibility to compile modules and load them without rebooting. This is supposed to be useful when I need a module ...
3
votes
1answer
4k views

iptables rule to allow access to internet

I made default policy of my machine- iptables -A INPUT -j REJECT #DROP ALL PACKETS TO INPUT CHANNEL INPUT channel has been blocked. Now I want to allow only some specific services like I should be ...
3
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1answer
230 views

iptables infographic

Is there an infographic somewhere that describes the logical flow of iptables? Specifically, I'm looking for something that diagrams which point in the process ip_conntrack applies.
3
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1answer
188 views

Linux App that monitors log and add rules to iptables

I used to use a linux software that monitors logs like http, ssh, etc and if it detects that someone is trying to use brute force, it blocks that ip by adding a rule to iptables. I forgot what that ...
3
votes
1answer
4k views

Using /etc/hosts or iptables to redirect site to https:// version

I'd like to have my system automatically take me to https://facebook.com even if I put http://facebook.com into my browser. I can get /etc/hosts to redirect to me to different domains, but it seems ...
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210 views

Why does SNAT happen in POSTROUTING chain and DNAT in PREROUTING chain?

Why does SNAT(modifies source IP and/or ports) happen in nat table POSTROUTING chain, i.e after routing? And why does DNAT(modifies destination IP ant/or ports) happen in PREROUTING chain? I guess ...
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3answers
429 views

Blocking Websites by days and hours using Iptables in OpenWRT

I want to block Facebook the whole day with the exception of the night. I want to implement that in my Linux-based router OpenWRT. The archive I need to modify is /etc/firewall.user (or at least that'...
3
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4answers
138 views

Mass IP Blocking

I have a game server and someone is spamming it with bots. The SpamBot client makes the handshake with my server using UDP connections. It does this through a list o proxies. Basically, the Spambot ...
3
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2answers
2k views

How do I fix iptables in ChromeOS?

Using the shell in chrosh in ChromeOS I followed some (apparently terrible) advice to flush my IP tables. using the command sudo iptables -F I am now unable to connect to the internet at all. All ...
3
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1answer
6k views

Log the dropped packets by IPTables only if its DROPPED by a specific rule

I have IPTables rules set on a Linux device. I have a particular rule to drop the packets, and I wish to log the packets only if they're dropped by that specific rule, and not by the other rules. ...
3
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2answers
2k views

How does iptables MASQUERADE work on the incoming side?

I'm still reading the iptables manual page and other documents and digging around questions and their answers. This is the problem which arises. When we setup the NAT we use a POSTROUTING rule such ...
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4answers
2k views

Can't add large number of rules to iptables

I made a very simple bash script (echo at start, runs commands, echos at end) to add approx 7300 rules to iptables blocking much of China and Russia, however it gets through adding approximately 400 ...
3
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2answers
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What is a solid iptables configuration for my desktop?

On my desktop, I want to configure iptables pretty strictly. I see no reason why I need to allow anything except for internet traffic that I initiated. And maybe even that could be limited to only a ...
3
votes
1answer
223 views

Debian-Jessie: How do you check iptables status?

In old sysvinit I would just do service iptables status and see if it was running or not. But in newer Debian-Jessie I grep for iptables in the list of services and don't see iptables listed anywhere....
3
votes
2answers
48 views

Why does my iptables firewall reject connections to port 1531?

When installing RHEL, iptables seems to be rejecting connections from 1531 (oracle). This is my configuration: # Firewall configuration written by system-config-firewall # Manual customization of ...
3
votes
1answer
220 views

What do the fields in /proc/net/ipt_hashlimit/FILE mean?

What do the fields in /proc/net/ipt_hashlimit/FILE mean? These files are created upon iptables -A CHAIN -m hashlimit--hashlimit-name FILE [...] [...] 9 198.51.100.23:0->0.0.0.0:0 80000 80000 160 ...
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3answers
484 views

How to make Raspberry Pi to receive an IP from a router and also pass another IP to another device?

I know that I could achieve the desired result with an Ethernet switch, but I'm curious if I can get this with some cheaper solution. The idea is as follows: Rapsberry Pi has two Ethernet ports - ...
3
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2answers
823 views

Is there a specific reason why iptables would return an exit code of 3 (instead of 1?) when executed without sufficient privileges?

I simply forgot to use sudo: usr@arch ~[0] $ iptables -L iptables v1.4.21: can't initialize iptables table `filter': Permission denied (you must be root) Perhaps iptables or your kernel needs to be ...
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2answers
198 views

How can I determine what program or user connected to a particular port after the fact?

I am examining the egress IPTABLES log of my computer for yesterday and notice the following: IN= OUT=eth0 SRC=192.168.1.1 DST=69.46.36.10 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=12345 DF PROTO=TCP ...
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1answer
2k views

Why iptables does not fetch information from /etc/sysconfig/iptables on centOs?

I'm new in Linux and encountered with problem with iptables. Here is content of /etc/sysconfig/iptables file # Generated by iptables-save v1.4.7 on Tue Nov 27 21:41:04 2012 *filter :INPUT ACCEPT [0:...
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2answers
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Why must loopback traffic be authorized using iptables to get web access?

I thought the following was necessary was necessary for outgoing HTTP on a desktop (non-server): iptables -A INPUT -p tcp -m multiport --sports 80,443 -m conntrack --ctstate ESTABLISHED -j ACCEPT ...
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4answers
22k views

iptables drop all incoming ICMP requests except from one IP

Currently, I have something like: iptables -A INPUT -p ICMP --icmp-type 8 -j DROP iptables -A INPUT -s x.x.x.x -p ICMP --icmp-type 8 -j ACCEPT However, when I run the second command, it ...
3
votes
1answer
3k views

iptables/pf rule to only allow XY application/user?

I think there is no iptables/pf solution to only allow an XY application on e.g.: outbound tcp port 80, eth0. So if I have a userid: "500" then how could I block any other communications then the ...
3
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1answer
218 views

Is there a standard way to configure what policy iptables loads on startup under Debian?

I've just started playing with Debian 6.0 (Squeeze) in a VPS environment, as a way to learn more about system administration. One thing I'd like to configure is a default packet filtering policy. (...
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2answers
875 views

Block specific IP from accessing gateway

Suppose you are on linux internet gateway/router. What would you do to block a client with specific IP using bash script. I prefer something like ./block_client.sh 192.168.1.123 to block and ./...