iptables allow creation of rules to define packet filtering behavior.

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3
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2answers
690 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 ...
3
votes
3answers
200 views

monitor bandwidth on interface with tc or iptables

I would like to log a warning message to /var/log/messages file if either ingress or egress bandwidth on eth0 interface is over a certain threshold. I could do this with a script which reads the value ...
3
votes
1answer
181 views

How to combine iptables rulesets

Say there are several iptables scripts (run at boot time), all of which run something like iptables -A ... to add rules. I'm thinking this could be improved, turning all those shell scripts into text ...
3
votes
1answer
227 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 ...
3
votes
1answer
320 views

Configure iptables on remote server without locking me up

I have a little remote server that I can access only with SSH, and what I want to do, is block all the traffic except port 22 for SSH. The first time, what I did was : iptables -P INPUT DROP And ...
3
votes
1answer
535 views

IPtables : Limit number of new ssh connections per minute

I need to ensure on my server that maximum new ssh connections per minute are not more then 5. sudo /sbin/iptables -A INPUT -p tcp --syn --dport 22 -m connlimit --connlimit-above 5 -j REJECT Above ...
3
votes
2answers
641 views

Is it possible to whitelist a specific program in iptables?

Is it possible to allow all traffic for a specific program in iptables? Otherwise using nmap and a strict iptables configuration at the same time seems impossible.
3
votes
1answer
904 views

Changing firewall settings after installation of CentOS via kickstart

I was trying to install CentOS 6.3 via Windows Deployment Server. And to automate the installation process I used kickstart file in which i provided various details required during installation.Then i ...
3
votes
1answer
667 views

How to measure iptables load?

I have added about 3500 IP addresses to iptables using ufw on a Debian 7 and I am wondering if this has any impact on the performance of my server. How can I measure that?
3
votes
1answer
580 views

Proper way to handle FTP over SSL with restrictive firewall rules?

Without SSL, FTP works fine over a stateful Firewall, like netfilter (iptables) + the nf_conntrack_ftp kernel module like this: # modprobe nf_conntrack_ftp # iptables -A INPUT -m conntrack --ctstate ...
3
votes
1answer
198 views

IPTables rules for specific processes [duplicate]

I have a lot more experience with the Windows Firewall with advanced functionality than I do with IPTables. With the WFAF, I was able to lock down a program so that it could only connect over specific ...
3
votes
1answer
2k 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 ...
3
votes
1answer
1k 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 ...
3
votes
1answer
388 views

listen to a conversation using port forwarding

I have been able to make a phone calls using the SIP client Pjsua from one Linux computer to another one. In case you have not heard of this user agent, explaining it's functionality is quite easy. It ...
3
votes
1answer
4k views

Set up firwall with iptables to only allow VPN

Im using IPredator VPN with openVPN and I want to make sure that if the connection is dropped, i wont submit data from the internet without the VPN. I heard that I could do that with iptables and a ...
3
votes
1answer
781 views

Routing through iptables

I have this vpn client that touches the routing table and then keeps watching it to exit if it gets touched. It is the kind of setup needed for an endpoint, such as a laptop. I want to use a small ...
3
votes
2answers
766 views

Need help with routing

I have set up a Ubuntu server, that I want to use as a router for my local office. The problem is, that I want to make 2 VPN connections, to remote branches, and then I want to route all traffic to ...
3
votes
2answers
69 views

How to disable network access for a user?

Trying to disable the network access for the user: [root@notebook ~]# iptables -I OUTPUT -m owner --uid-owner tempuser -j DROP [root@notebook ~]# ip6tables -I OUTPUT -m owner --uid-owner tempuser -j ...
3
votes
1answer
203 views

How to combine connlimit with IP sets?

connlimit lets me limit the number of connections per client/service. How would I go about to combine such a rule with the IP sets available in more recent versions of the Linux kernel and netfilter?
3
votes
1answer
47 views

Which network services depend on the “accept related input” iptables rule?

Background I am setting up a firewall for a webserver and was wondering if it would be a good security meassure to even reject RELATED input traffic and only except established connections by ...
3
votes
1answer
2k views

I opened a port with iptables but still doesnt work

I have a CentOS installation as a guest VM with VirtualBox. I have two ethernet interfaces, eth0 with NAT and DHCP, and eth1 with Host-only adaptor and static IP. I have oracle installed in this ...
3
votes
2answers
720 views

iptables routing marked packets from router to PC and routing them back to router

I'm trying to do deep packet inspection on HTTP packets. The purpose of this is to collect HTTP payload data and then create some proxy/cache-independent reports. Following this, the idea is to ...
3
votes
1answer
3k views

tc don't see marked with -j MARK packets

Server has 2 network interfaces: eth1 with address 13.0.0.254/24 eth0 with address 172.20.203.4/24. It's routing traffic between this two networks. Task is to limit bandwidth between this two ...
3
votes
1answer
451 views

User associated with a socket

I use ss -p to see TCP sockets information. But process info are not printed for some sockets. Below: $ ss -p4 State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 0 ...
3
votes
1answer
397 views

1000 iptables entries on CentOS?

I just got a new dedicated server with CentOS and I'm trying to debug some network problems. In doing so, I found over one thousand iptables entries. Is this the default on a CentOS system? Is there ...
3
votes
1answer
3k views

Default mark for packets using iptables

I am trying to set up a QOS script on my Tomato-enabled WRT54G router. The script does the basics of what I need (make sure that a particular machine on my network has lower priority than anything ...
3
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0answers
254 views

Is it possible to throttle upload bandwidth per `IP` basis using `tc`, `htb` and `iptables` ? (Download limitation not required)

Problem I've searched internet like anything but couldn't find much about limiting upload. The solutions given are not limiting IP basis like this one but LAN as a whole. +-----+ ...
3
votes
0answers
113 views

Restrict the maximum number of independent IP connection on specific port at the same time

I set up a server as a socks5 proxy. I'd like restrict the maximum number(1 or 5 or 20) independent IP connection on specific port at the same time. I have searched on google, only see some articles ...
3
votes
0answers
192 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 ...
3
votes
0answers
115 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 ...
3
votes
1answer
148 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 ...
3
votes
1answer
111 views

Why are these connections not classified as “established” under conntrack?

I have the following rule for iptables: -A OUTPUT -m conntrack --ctstate ESTABLISHED -j ACCEPT such that outgoing connections not classified as established will be logged. Occasionally, the ...
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0answers
44 views

Which tool is used to create firewall rules on Fedora 20? [closed]

What is a recommended way to set up firewall rules on Fedora 20/Centos 7/RHEL 7 currently? I know about relatively new replacement of itpables service by firewalld service. Which command-line user ...
3
votes
1answer
142 views

IP rule table look up does not seem to work

I have a sytem with three network interfaces. Below is the configuration that I'm trying to set up. wlan0 (its actually an WiFi AP interface) - other devices connects via this interface. net1 - ...
3
votes
0answers
282 views

iptables hangs at applying rules

I have a set of rules that are supposed to give me the most protection before things like fail2ban and other things are added to the mix. The issue is that although everything checks out in the test, ...
3
votes
2answers
133 views

Iptables not forward traffic

I need to redirect all traffic incoming on port 9750 (the port chat server) to another machine on the same subnet. Ports clients - dynamic. iptables -t nat -A PREROUTING -p tcp -d x.x.x.a --dport ...
3
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0answers
103 views

Packets do not cross IP tables Postrouting when originating from an external IP

I'm trying to reflect traffic from the internet to an internal device that I only want to have local access. I have a host in my DMZ that I'm trying to DNAT traffic to this internal device, and SNAT ...
3
votes
1answer
155 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" ...
3
votes
1answer
134 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 ...
3
votes
2answers
643 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 ...
3
votes
0answers
194 views

iCloud stuff stops working while connected to OpenVPN

I have a fairly simple OpenVPN setup on an OpenVZ VPS with Ubuntu 11.10. Client is the Viscosity client on Mac OS X 10.8.2, and after some testing, we can rule out the client as being part of the ...
3
votes
0answers
730 views

tunneling FON traffic via Tor

I would like to tunnel the traffic of my FON router through Tor. For that I added a second network card to a local server and connected the FON router to it. Then I set up a DHCP server and configured ...
3
votes
1answer
697 views

Port Mirroring in Fedora? [closed]

I have set up an application that listens constantly to a port for network packets, and I would like to create another one that receives the same network packets ( for use as a test bed). Getting the ...
3
votes
2answers
1k views

Open and redirect port

I'm trying to set up SNMP for a router so I can monitor it from an existing Nagios installation on an off-site server. I'm having trouble getting the router to respond to SNMP requests from the WAN, ...
2
votes
2answers
5k 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 ...
2
votes
6answers
442 views

Recommend a reading for learning Linux firewalls configuration for beginner? [closed]

I am using Linux at home and want to be able to configure firewall. I would like to understand what I am doing not just copy paste some rules from internet :).
2
votes
2answers
14k views

IPTables rule to allow incoming SSH connections

The aim of this script is to only allow traffic over the VPN, except for localhost<->localhost and incoming SSH traffic. But when I run the script over SSH I am disconnected and forced to restart ...
2
votes
2answers
146 views

Block all IPs from accessing anything on the server

I want to block all IPs except for my own home IP from doing anything on my server. How can I do this with iptables? For the example lets say my home IP is 1.2.3.4 My server still needs to be able ...
2
votes
3answers
5k views

bash: iptables: command not found

How do I fix the iptables: command not found problem that happened to Debian 7.6? batman@gotham:~$ uname -a Linux gotham 3.14-0.bpo.2-amd64 #1 SMP Debian 3.14.13-2~bpo70+1 (2014-07-31) x86_64 ...
2
votes
2answers
167 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 ...