iptables allow creation of rules to define packet filtering behavior.

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2answers
111 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 ...
2
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2answers
477 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 ...
2
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1answer
77 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
64 views

Should IP tables rules affect a serial port on Linux

I'm trying to setup some iptables rules on my embedded Debian Linux system, using a serial console I entered this: root@ts7600-47aad3:~# iptables -F root@ts7600-47aad3:~# iptables -P INPUT DROP ...
2
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1answer
104 views

Port forwarding using iptables on Linux

I want to forward a local port to a remote port (8041) to a port (8042) on a remote machine (10.0.0.42). I can do this via ssh -L 10.0.0.41:8041:10.0.0.42:8042 user@localhost where 10.0.0.41 is ...
2
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1answer
55 views

How would I go about making this IPTABLE rule for every ip and not just one?

iptables -I PREROUTING -t nat -p udp -s 192.168.0.62 --dport 53 -j DNAT --to-destination 23.21.182.24 Instead of 192.168.0.62 I'd like to set that as a global rule, EVERY ip that needs dns should ...
2
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5answers
164 views

Difficulty setting up iptables

I'm very new to *nix operating systems, and I'm having some trouble which I believe is because of misconfiguration of the iptables firewall. My server has SSH running on port 22, and server software ...
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2answers
2k views

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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1answer
480 views

IPTables string match redirection

The issue: I am currently redirecting port 80 requests to another system on port 1000. This is done like so: iptables -t nat -A PREROUTING ! -s 172.20.1.2 -p tcp --dport 80 -j DNAT --to-destination ...
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1answer
3k 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. ...
2
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1answer
831 views

iptables rules too restrictive; Drupal webserver cannot access repositories, ntp or even websites

This is a Drupal website running Ubuntu 12.04 LTS on Linode. Someone recently changed our iptables rules and a number of problems started. These include: Our Mollom spam protection is not working ...
2
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1answer
362 views

Can iptables be used to convert a single-homed host into a NAT server?

Given: I have a machine (HostA) with only one NIC which has Internet connectivity. I have another machine (HostB) with one NIC on the same switch. HostB is not configured for Internet access yet. ...
2
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1answer
230 views

Explanation of bandwidth management script calling tc

I have some scripts in Linux to manage internet bandwidth, but I do not understand what they do. What is the meaning of the following scripts: tc qdisc add dev $IF root handle 1: htb default 256 tc ...
2
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1answer
345 views

iptables is not blocking

I have a script running every minute by a crontab. This script scans the system logs and grabs the IPs of every failed attempt to login on the server's dovecot, exim or ssh and add them to an ipset, ...
2
votes
1answer
386 views

IPtables command shows libipt_random.so missing

When I run a command, it shows error. I searched on net, but no one give me the correct answer. Googling shows only wrong answers for this questions. So please help me to overcome this problem. ...
2
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2answers
589 views

Is xinetd still the best method to let non root daemons listen on privileged ports?

When I need to use SNMP monitoring for java applications, there is the need to that application (usually ran as daemon user) to listen on snmp port. If there is no other alternative, of course I can ...
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2answers
1k views

How can I Forward a subDomain to a specific port?

My apologies if this has been asked before. I haven't found an adequate solution so... yeah. When a specific domain, "example.com" is accessed, I want it to act normally. In other words, it should go ...
2
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1answer
2k views

Port Mirroring using iptables - copy all traffic among nginx on :80 and apache on :8080

I have nginx running on port 80 and apache running on port 8080 I want to transfer all the traffic to both nginx and apache asynchronously i.e the performance of one server wont be dependent on the ...
2
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1answer
9k views

Fedora 16 - Iptables installed, but no iptables service available

I'm trying to open ports on my fedora OS. In the past, this was as easy as adding an rule like -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT I went to restart my iptables ...
2
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1answer
1k views

What does this iptables entry mean?

iptables-save output: *filter :INPUT DROP [2929:172650] :FORWARD DROP [0:0] :OUTPUT ACCEPT [74596344:6265371965] These are the opening lines of the iptables-save command. What do the numbers in the ...
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1answer
2k views

Unable to make outbound SNMP connections when IPTables is enabled

I have a bunch of windows servers configured with the windows SNMP agent. Each server has four IP addresses and SNMP listens on all of them. There is something very odd with my monitoring server ...
2
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1answer
44 views

iptables ruleset causes server to stop answering

I'm trying to configure my proxmox server's firewal and redirections. The aim is to block everything, open the necessary ports for basic services to work and, finally, redirect some ports to virtual ...
2
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3answers
112 views

Bridge/Router with custom logic

I've a Linux box with 3 network adapaters, which I'd like to configure as follow: Adapter A is connected to computer A Adapter B is connected to computer B Adapter C is connected to the Internet. ...
2
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1answer
347 views

Forwarding packets from loopback interface with policy-based routing

I have the following iptables rule: iptables -t mangle -A PREROUTING -p udp -m udp --dport 10000 -j MARK --set-xmark 0x4/0xffffffff which sets fwmark 4 on all udp packets with destination port ...
2
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1answer
141 views

iptables routing incoming IP to another destination IP question

I have a test setup: server1:1.1.1.1 server2:2.2.2.2 client: 3.3.3.3 I'm trying to have client IP 3.3.3.3 do a HTTP request from the 1.1.1.1 server. However I want the 1.1.1.1 server to pass this ...
2
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1answer
75 views

psad: do not block access to HTTP

I want to block intruders via psad, but HTTP and HTTPS should not be blocked. For example, if someone is scanning my dedicated server via nmap, psad should block him for 2 hours, but he should still ...
2
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1answer
136 views

How is whonix blocking UDP traffic (except udp-dns related traffic)?

I want to know how whonix manages to block unwanted UDP-Traffic i.e. all UDP-traffic but DNS related udp traffic. I looked at the iptable rules both in the Workstation and Gateway. There are no ...
2
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1answer
607 views

Unable to access website hosted on virtual machine

I'm on a mac (osx 10.9.3) running CentOS7 in virtualbox. I would like to access the website hosted on the virtual machine. Browsing to the Guest IP returns webpage not available. I'm able to ping and ...
2
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1answer
260 views

In iptables, what is the difference between targets DNAT and REDIRECT?

More specifically, is -A PREROUTING -i $INT -p $PROTO --dport $PORT -j REDIRECT --to-ports $NEWPORT equivalent to one or both of these? -A PREROUTING -i $INT -p $PROTO --dport $PORT -j DNAT ...
2
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1answer
93 views

How do I enable IPv6 inbound traffic to get forwarded to my machine?

It seems that IPv6 traffic on my router is being dropped. How do I configure ip6tables appropriately, so that traffic is forwarded/accepted to my machine? Here's the syslog for my IPv6 traffic: Jun ...
2
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1answer
37 views

My iptables works the opposite from what I wanted

I have this set of iptables rules ... $ sudo iptables -n -L Chain INPUT (policy ACCEPT) target prot opt source destination LOG all -- 0.0.0.0/0 0.0.0.0/0 ...
2
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1answer
278 views

iptables - add rule for interface before it comes up

Right now I'm using /etc/rc.local to add some iptables rules on my Linux router on boot however some of the rules aren't added. I assume this is because the interface hasn't come up yet. This is what ...
2
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1answer
162 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 ...
2
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1answer
490 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. ...
2
votes
1answer
105 views

Forward a host's network traffic to another host with the exception of SSH traffic

I am trying to redirect all the network traffic received in a old host to a different host. For that I created two new rules with iptables on the old host: echo 1 > /proc/sys/net/ipv4/ip_forward ...
2
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1answer
642 views

iptables: redirect local request with NAT

I'd like to redirect local requests to port which is translated with NAT. I have following rules: iptables -t nat -A PREROUTING -p tcp --dport 9020 -j DNAT --to 10.0.3.11:80 however request coming ...
2
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1answer
155 views

Randomizing the source port for new connections

Generally whenever source port is selected by a network application, it is selected in a sequential manner among the free ports like 32000, 32001 and so on. I want to randomize the source port ...
2
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1answer
113 views

Internet sharing with iptables: choosing which connection to share

I have a computer with two network devices (eth0 and wlan0), both connected to the internet (two different connections/isp). I'm trying to share the connection of wlan0 to another computer connected ...
2
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2answers
244 views

RELATED,ESTABLISHED state in iptables

What do the words 'RELATED' and 'ESTABLISHED' individually signify in RELATED,ESTABLISHED state in iptables?
2
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1answer
2k views

Linux Fedora 19 - iptables failed to start

I've been trying to start the iptables firewall service, but it keeps failing. What's going wrong? # systemctl status iptables.service iptables.service - IPv4 firewall with iptables Loaded: loaded ...
2
votes
1answer
180 views

What are the pros and cons to editing iptables configuration file vs adding rules via the iptables command

I am working with a product on CentOS that occasionally needs to automatically add and remove rules from the iptables configuration. For example, during an update, we want to explicitly refuse ...
2
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2answers
3k views

Open a port in my CentOS

I'm trying top open a port on my CentOS machine: I edit the /etc/sysconfig/iptables file and add my rule: -A INPUT -p TCP -m state --state NEW -m tcp --dport 143 -j ACCEPT Then I restart the ...
2
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1answer
1k views

Local port forwarding automatically configured on boot?

I have software which needs to run as a non-root user, but needs to listen on port 80 and 443. With iptables, this isn't all that difficult: sudo iptables -t nat -A PREROUTING -i eth0 -p tcp ...
2
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1answer
251 views

Allow application specific access in iptables using guid

I would like to get Skype working with iptables and don't want to allow a huge range of ports thus I thought a solution might be iptables -A OUTPUT -m owner --gid-owner skypeGrp -j ACCEPT iptables ...
2
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1answer
120 views

Using iptables to block for specific services

I am using ipset in conjunction with iptables to create a list of IPs I want to block. I did this: ipset -N blocking iphash ipset -A blocking 124.205.11.230 // and repeated this line for all IPs I ...
2
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1answer
238 views

Linux nat/iptables configuration for a chain of peer-to-peer links

I have an experimental setup, of 4 Linux (CentOS) machines: All 4 machines are internally connected using different networks and can ping eachother directly connected interfaces. However only PC4 ...
2
votes
1answer
256 views

PPTP server with NIC aliases

I have set up a VPN on a VPS Server using PPTP. I have one NIC with two aliases. eth0 eth0:1 eth0:2 The 3 interfaces have public addresses. eth0 is a French IP, eth0:1 is UK, and eth0:2 is ...
2
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1answer
1k views

Need to access port on LAN through IPTABLES firewall on static IP interface

I have a Linux firewall with 3 NIC's. Eth1 is my LAN's default gateway and has IP address 10.1.2.250 and is connected to my LAN with IP range 10.1.2.0/24. Eth2 has IP address of 10.0.0.6 and gateway ...
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2answers
1k views

Checking the type of NAT

I have read that there are many types of NATs available like symmetric NAT, full-cone NAT, etc. If I am behind a NAT, is there any way to find out the type of NAT behind which I am currently working ...
2
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2answers
800 views

use iptables to allow incoming connections to some computer on port XYZ?

This is what I have: iptables -i em1 -A INPUT -j ACCEPT -p tcp --dport 9001 -v. If I want to accept incoming connections on port 9001 at this (127.0.0.1, or on the network 192.168.1.143) address, ...