iptables allow creation of rules to define packet filtering behavior.

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Defining IPv6 chains in ip6tables-restore/iptables-restore files, is it possible?

The format for the files generated by iptables-save/ip6tables-save and loadable through iptables-restore/ip6tables-restore stipulates that one can prepend -4 or -6 respectively so as to maintain the ...
2
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1answer
80 views

Remove an IPTable Rule

I'm having troubles removing this ipables rule in Ubuntu: $ iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 3128 I've tried using the -D attribute but with no success. How can ...
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1answer
36 views

Creating a virtual interface to always access a DHCPed interface with the same ip

I have an interface that on connect always gets a new IP. So I want to create a virtual interface with a static IP that "relays" everything over the physical interface. This would be useful to bind ...
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0answers
77 views

CPU usage by kernel modules, routing and forwarding rules

I have a system with a loopback kernel module installed. Through a bunch of routing and iptable rules, packets coming out of the loopback interface are sent over an ipsec tunnel. I am seeing that ...
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1answer
52 views

Routing packets between networks with iptables

I'm trying to create a proxy of sorts using just iptables. The linux computer (my proxy) has two ports: p2p1 is connected to the Internet. em1 is connected to a local network. There are two ...
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2answers
96 views

IPtables reset on reboot, how do I tell what is causing this

Using RHEL, and I have had some "Cyber Security" people work on my server. I'm now using this server in a completely closed environment with no outward network connection, and would like my iptables ...
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1answer
467 views

iptables based redirect captive portal style

What is a iptables set of rules that will force hosts connected to a access point, that try to access any website (port 80 of any ip or hostname) to be redirected to another device on the network ...
3
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1answer
59 views

iptables: refuse immediately when blocking particular domain from visiting by browser

I need to block particular domain "megafonpro.ru" and all subdomains from visiting by browser. Here's rule that I wrote: sudo iptables -I OUTPUT -p tcp --dport 80 -m string --string "megafonpro.ru" ...
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2answers
153 views

Bonding two broadband connections to serve LAN as a gateway

I need to increase the connectivity and speed of the Internet to my LAN users. These are the things I have in my hand to do so. PC with 3 NICs 1 for LAN and 2 for routers 2 broadband connections ...
4
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2answers
109 views

Can iptables rules manipulate IP sets?

In iptables-extensions(8) the set module is described and it is discussed that it is possible to react to the presence or absence of an IP or more generally a match against an IP set. However, it ...
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90 views

IPTables 1.4.7 dropped allowed packet

When looking in the /var/log/messages file I found this line: May 23 10:56:02 localhost kernel: IP4T Invalid TCP flags IN=eth0 OUT= MAC=70:5a:b6:ec:95:6b:00:23:48:ad:b0:a4:08:00 SRC=A.B.C.D ...
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1answer
85 views

IPv6 firewall rules seem to impede all connections

After deciding that my small server needed a firewall, I used ferm to configure iptables and ip6tables for me (this question should be tagged ferm, but I cannot create the tag). I am using the same ...
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1answer
34 views

Redirect packets and save the content to disk

I want to reroute a connection just like rinetd does but save the client and server messages. Is there any tool like this out there ? I'm using Debian.
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1answer
47 views

IPtables on ubuntu 12.04

I've problem with iptables on ubuntu 12.4. I type ufw status, it show result Status: inactive but I type iptbles -L -nv, it still shows many rules, and these rules are running. I can't understand.
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1answer
86 views

Absolutely cannot get FTP access after adding many rules to iptables in CentOS5

I'm a complete noob and am just having the worst time trying to get FTP access to the server. I want to keep the firewall enabled. Edit: Updated the iptables information. I have the following ...
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112 views

Running a Transparent Proxy for LAN and Webserver for WAN

I am running a LAMP stack on an Arch Linux server in my home, and my router firewall port 80 is open to the world. Recently, I've decided to set up a dansguardian transparent proxy to do some web ...
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0answers
33 views

How do I route traffic between eth0:0 and eth0 [duplicate]

I have been trying to convert my linux box which is running Mint into a router. eth0 has a public IP address of 71.xx.xx.xx. I created an eth0:0 and gave it an IP address of 10.0.0.100. I started a ...
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1answer
174 views

What are the definitions of addrtype in iptables?

I am keen to use addrtype in combination with -src as a rule in one of my filter chain like so to drop some bogon ips: -A INPUT -p tcp --dport 80 -m addrtype --src-type UNICAST ! -s 127.0.0.0/8 -j ...
2
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1answer
72 views

What does lo in iptables mean exactly?

I have seen countless examples of this rule in iptables: -A INPUT -i lo -j ACCEPT I thought lo means localhost (a.k.a. 127.0.0.1), but when I commented it out, I can't access the server using its ...
2
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1answer
94 views

IPTables Port Redirection Should Have Broken Apache But Didn't

I have a Load Balance set up in Apache httpd: <VirtualHost *:80> DocumentRoot /var/www/html ServerName xxx.xxx.xxx.com ProxyRequests Off ...
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1answer
29 views

Unable to access external content with this IPTABLES ruleset

My application server is on a network protected by a organization wide firewall, and my server is also using fail2ban. That said, I'd like to set up an additional layer of protection with iptables. ...
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3answers
54 views

Iptables in linux

Please explain me the use of bold character below iptables -A INPUT -i eth0 -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT -A -i -p -m state --state -j
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1answer
39 views

Do I have to swap IP sets, or can I add/remove on the fly?

I was wondering about the semantics of ipset(8). Is it possible to add a rule matching a set to iptables and then manipulate the set, or can I only create a set and swap it for an older set in order ...
2
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1answer
183 views

Problem setting up iptables (LDAP traffic blocked)

My application server is on a network protected by a organization wide firewall, and my server is also using fail2ban. That said, I'd like to set up an additional layer of protection with iptables. ...
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1answer
75 views

How to log incoming icmp traffic?

I am watching my ip6table and observing an icmp packet arriving and getting dropped at the rate of 1 per second. I am trying to find out what that message is about. I tried using tcpdump (it is ...
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350 views

Port redirection on loopback with IP other than 127.0.0.1

I want to redirect port 80 on the loopback network interface so that accesses to that port actually go to port 8080. I tried using the following command, but it only works if the application is ...
2
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1answer
310 views

How does connlimit in iptables supposed to work?

I wanted to set a limit to the number of concurrent connections allowed on my web server. I tried the following rules on an iptables (v1.4.19.1) kernel 3.14.4-200.fc20.x86_64 with a default DROP ...
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160 views

iptables server behind NAT accessible from outside as well as inside the nat

I have 2 machines with a KVM running on each machine - so two kvms with the below networking Host 1: 192.168.10.100 (eth2) 10.10.100.1 (virbr1) KVM 1 (NAT with Host 1): 10.10.100.128 (eth0 ...
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2answers
137 views

What is the simplest method to redirect traffic using either a proxy or iptables?

I need to redirect all incoming traffic on port 7777 to a specific destination_ip:port. I have about 40 Litecoin (scrypt) mining rigs that I have to manually reconfigure each time I'd like to switch ...
3
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3answers
233 views

dmesg flooded with firewall logs

In my iptables, I have a rule which logs dropped packets: -A INPUT -i eth0 -j LOG --log-prefix "FW: " --log-level 7 -A INPUT -i eth0 -j DROP And in /etc/rsyslog.conf, I have ...
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37 views

iptables drop length and TTL condition doesn't work

With iptables utility on Linux host need to create mini firewall. I need to drop all incoming connections with package length greater than 722 AND TTL greater than 22. Need exactly AND. Drop only if ...
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1answer
157 views

RHEL 6.5 won't boot after loading APF firewall

We have an RHEL 6.5 system which boots to the point of loading APF firewall and then just hangs indefinitely. The console shows the following: ... Loading autofs4: [OK] Starting automount: [OK] ...
0
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1answer
360 views

Disable iptables service on CentOS

I don't want the service to start after reboot. my code does this: service iptables stop service iptables save chkconfig --level 123456 iptables off service iptables status iptables: Firewall is not ...
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2answers
180 views

Use IP tables to port forward behind a router?

Is it possible to use IP tables to port forward behind a router? My setup is thus: I have a Raspberry Pi running a small website on port 80, and a beefier computer running a Minecraft server on port ...
1
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1answer
374 views

Create a iptables rule if the rule does not all ready exist

Hi I've created a script to setup Nagios on my remote servers. My Script checks iptables to see if a firewall rule all ready exists and then is supposed to add the rule if it's not all ready there. ...
5
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1answer
187 views

Skip routing via `lo` interface for outgoing packets

Introduction I have following load balancing configuration: 10.0.1.31 - lb 10.0.1.35 - virtual IP 10.0.1.32 - node1 (tomcat + mysql) 10.0.1.33 - node2 (tomcat + mysql) I'm using keepalived which ...
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1answer
37 views

View blocked address from sshguard

How can I view all the addresses that sshguard has blocked to iptables?
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2answers
72 views

Does IP tables need to be configured or is a stand alone firewall sufficient?

I have two desktops and a laptop running Arch Linux. I have not setup any iptable rules on any of the machines, and I am curious if I should. One desktop is only used in my home network and is ...
4
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1answer
127 views

Can iptables be used to monitor TCP timeouts/resets system-wide?

I'm trying to determine if an application's connection to a database is internal to the application or due to a networking event. This seems like something netfilter would have system-wide visibility ...
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2answers
58 views

iptables advice with upd ports blocking in debian linux [closed]

please advice: I add next iptables rules: iptables -I OUTPUT 2 -p udp --dport 53 -j ACCEPT iptables -I OUTPUT 2 -p udp --dport 1700:1750 -j ACCEPT iptables -I OUTPUT 3 -p udp -m udp --dport 1812 -j ...
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126 views

What is wrong with these iptables' rules?

The following is what I got after googling: iptables -A INPUT -i lo -j ACCEPT iptables -A OUTPUT -o lo -j ACCEPT #allow loopback access iptables -A OUTPUT -d 255.255.255.255 -j ACCEPT #make sure you ...
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1answer
899 views

iptables forward all traffic to interface

I have two interfaces eth1 and eth0. I want all traffic on eth0to be forwarded to eth1. I created an iptable rule like this: iptables -A FORWARD -s 0/0 -i eth0 -p tcp -o eth1 -j ACCEPT But this ...
0
votes
1answer
589 views

IPTables allow NTP Time Server

I am new to IPTables. I have an existing config that seems to work well. I am not sure I know how to add NTP to the rule Chain RH-Firewall-1-INPUT correctly. My goal is to add an additional rule to ...
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1answer
107 views

configure exim for system email forwarding (outside) , on a server with dynamic ip, behind a DNS router

Trying to configure exim to deleaver email to the outside world. I/We need to send email outside just for centralize certain admin notifications. Working on an already configured debian webserver, ...
2
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2answers
421 views

Why isn't the Iptables persistent service saving my changes?

I followed this tutorial to set up IP rules on ubuntu 12.04. Everything worked fine on setup -- but now I've made changes to the firewall that do not persist upon reboot. I do not understand why that ...
3
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1answer
197 views

Settings when using a bridge

I have a bridge set up between my physical Ethernet interface, eth0, and the virtual interface for OpenVPN, tap0. The bridge has an IP address, and the machine can be contacted on that IP address from ...
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1answer
31 views

What is the meaning “MAC MISSMATCH”? [closed]

I have every day in the log the few lines start with: MAC MISSMATCH:IN=vlanXX OUT= MAC=ff:ff:ff:ff:ff:ff:bc:ae:c5:da:70:a6:08:00:45:00:00:4e SRC=xx.xx.xx.xx DST=xx.xx.255.255 LEN=78 TOS=0x00 ...
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2answers
98 views

Are there ways to break into a machine if iptables drops all traffic?

Say I install Linux on an blank computer (no other OS, disk is formatted for installation), and I configure this in iptables: iptables -F iptables -P INPUT DROP iptables -P OUTPUT DROP iptables -P ...
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0answers
23 views

How can I use iptables to block certain processes from accessing the network? [duplicate]

I can set the processes to run under special uid's and use the technique from this SF answer: -A OUTPUT -m owner --uid-owner 400 -j DROP ...But are there any other ways to blacklist based on the ...
4
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1answer
161 views

Debian Wheezy subnet configuration (proxy, MASQUARADing etc.)

I have a "server" with eth1 having a full IP address, DNS, gateway and proxy name connected to the university internet/intranet provider and eth0 IP 192.168.1.2 connected by a gigabit switch with two ...