iptables allow creation of rules to define packet filtering behavior.

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51 views

Is iptables -p proto -m proto redundant?

I keep seeing "-p tcp -m tcp" all over the place, but it looks redundant. Why the '-m' if the '-p' already matches the protocol?
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1answer
63 views

How to map IP by iptables ?

I create a network namespace In this namespace, I open a nginx So for now, I can visit web server by 172.17.0.2 What I want to do is mapping this IP to 127.0.0.1 Lets say if I visit 127.0.0.1, I ...
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162 views

Iptables and Ip6tables redirect traffic

I want to deny all the network traffic and just allow a few ports and redirect them through tor or the socket I have set in /etc/tor/torrc, where tor binds to. And I am currently setting up these ...
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45 views

How do I write the rule that has an edge server forward a clients request to an internal network server and back?

I have a network situation as follows: -server1:1.1.1.1 -server2:2.2.2.2 -tunnel 10.8.0.0/24 -client: 3.3.3.3 I'm trying to have client IP 3.3.3.3 do an HTTP request from the 1.1.1.1 server. ...
2
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1answer
272 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 ...
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1answer
35 views

Does -o and -i make sense when the target host is already connected to the interface specified?

iptables -A FORWARD -s 192.168.20.7 -d 10.10.48.3 -p tcp --dport 25 -o eth1 -j ACCEPT iptables -A FORWARD -s 10.10.48.3 -d 192.168.20.7 -p tcp --sport 25 -i eth1 -j ACCEPT Tuning the firewall of my ...
6
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1answer
96 views

Setting traffic class on return packets

I have a network topology: Server <-> router1 <-> router2 <-> router3 <-> edgeRouter <-> "internet" All routers are linux based, and support iptables. The server sets ...
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123 views

Sabayon: UFW blocking all incoming connections, although default policies are set to “Allow”

I have the following problem with ufw/iptables: When I start/reboot my computer, ufw fails to load: # ufw status Status: inactive I did enable it: # systemctl enable ufw Still I do have many ...
0
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1answer
196 views

Route OpenVPN clients to another different OpenVPN server

I have this scenario.. Server(Primary) with a multiple OpenVPN connections (so server is connected as a client to multiple OpenVPN servers.. lets say secondary servers) This server runs OpenVPN ...
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2answers
293 views

Drop TCP packets and prevent TCP retransmission

I have an application that sends TCP data to a server. My server is made to intentionally drop the packets sent by the application, and as a result the client retransmits the packets. I need to ...
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2answers
99 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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733 views

iptables to allow teamviewer

I'm having some trouble to allow TeamViewer in a restrictive iptables configuration. I'm running Fedora 20. After some research I found out TeamViewer uses ports 80, 443 and I have created this ...
2
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0answers
576 views

How do I route bittorrent through a second interface?

I've managed to configure openvpn on my DD-WRT router such that the tunnel is up and working, but that it doesn't mess with routes at all (the default configuration wants all traffic to go through ...
3
votes
1answer
115 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 - ...
2
votes
1answer
110 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 ...
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1answer
83 views

How to use partial IP address in /etc/sysconfig/iptables for the “-s” flag?

in this example it is a full ip ip is: 1.1.1.1 -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -s 1.1.1.1 -j ACCEPT but suppose i want to allow any ip that simply starts with: 1.1. ...
0
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1answer
940 views

iptables redirect traffic from VPN interface to next interface

Can you help me with this problem please? I need redirect all traffic from tun0 interface (OpenVPN tunnel) to eth1 interface. eth1 is internal network behind this system which works as special ...
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2answers
251 views

Redirecting loopback traffic through a router

For some tests purposes, I am running multiple socket-based applications on one machine and want to simulate "real" network conditions between them. I thought the simplest would be to redirect all ...
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3answers
1k views

Redirect domains to different ports on same machine

I used the following command to redirect 80 to 3000. All the requests that come, from any domain, are redirected to 3000: sudo iptables -t nat -I PREROUTING -p tcp --dport 80 -j REDIRECT --to-port ...
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votes
2answers
408 views

Domain Name problems in CentOS hosted under VirtualBox

When I ping www.google.com I get: [root@ryanPC ~]# ping www.google.com ping: unknown host www.google.com Also, when I run ping -n 8.8.8.8, I get: connect: Network is unreachable So I have ran the ...
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1answer
87 views

iptables routing

I believe this question has been answered a 100 times before, but I'm almost sure that I'm searching into the wrong direction. My desired setup is the following: I have a virtual host using KVM and ...
2
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3answers
3k 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 ...
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2answers
4k views

How can I make iptables service start automatically after reboot on CenOS/RHEL7?

I am having a few issues with a newly installed home server I am preparing. I have installed CentOS7 on it and I found that port 80 and 443 are off by default. I therefore added them to the iptables ...
2
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2answers
187 views

Delay when iptables icmp rules take effect

I have setup my iptables to disable all incoming connection, i.e. :INPUT DROP [0:65535] When the iptables has been started, I run the following command to enable ping: /usr/sbin/iptables -A INPUT ...
3
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1answer
379 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 ...
2
votes
1answer
175 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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0answers
173 views

iptables rule to transfer UDP through a SSH tunnel

The problem I have two programs that runs on two distant computers and communicate through a specific protocol. All I know is that this protocol only communicates through UDP and uses the ports 1101 ...
0
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0answers
584 views

Upon bootup, all iptables are lost because the kernel module ip_set is not loaded

i can get iptables to whitelist / blacklist using ipset members, but after a reboot, the iptables are emptied out because the kernel module is not loaded. Have limped along in the past by customizing ...
0
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1answer
71 views

how to find out wich chain in iptables in listing

Suppose I have the following two entries line of iptables: iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE iptables -A INPUT -s 192.168.1.0/24 -j DROP So, I have POSTROUTING and INPUT chains. ...
3
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1answer
3k views

Configuring OpenVPN to use Firewalld instead of iptables on Centos 7

I need some help configuring OpenVPN on Centos 7 using firewalld. I used iptables on Centos 6.5 and only had to add the following lines to /etc/sysconfig/iptables: -A POSTROUTING -s "10.0.0.0/24" ...
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252 views

IPtables Packet Balancing

I would like to see the below work as a result of seeing several posts online that have this working but not quite the same as my situation. Forgive me if it appears to be a stupid idea as I'm now ...
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1answer
50 views

Confused by different output from iptables -L

I keep following this tutorial using a bash shell on ubuntu 12.04 as I open more and more ports on my server. I usually open up ports like this sudo iptables -A INPUT -p tcp --dport PortNumberToOpen ...
0
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1answer
51 views

What this Iptables rules does?

I think I can understand this iptable rule, but I want to make sure what it does, so can someone explain to me technically what this does? well this two rules combined. /sbin/iptables -t nat -A ...
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33 views

Extra overhead in MASQUERADE target

There's a part in iptables manual concerning SNAT and MASQUERADE targets. I know the key difference between the two, but I don't fully get the following sentence: It is still possible to use the ...
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114 views

How can I use 0.0.0.0/0 in ipset hash:net,port?

Right now, if I do ipset a ansible_allowed 0.0.0.0/0,tcp:22 I get ipset v6.19: The value of the CIDR parameter of the IP address is invalid and instead I have to add 0.0.0.0/1,tcp:22 ...
3
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1answer
148 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
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1answer
43 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 ...
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1answer
202 views

MYSQL : Connecting to mysql from : 127.0.0.1 + telling ip tables to allow only 127.0.0.1 for mysql port : Logic vs Common Sense

If i make 1 billion or 1 trillion queries to MYSQL database from 127.0.0.1 via port 3306. vs If i make same amount of queries to MYSQL database also from 127.0.0.1 via port 3306. but with ...
6
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2answers
2k views

Move iptables rule (w/o removing and adding)

Is there a way to move a rule in the iptables and change it position ? I'm aware i can use -I to insert a rule in a specific position, but i also like to keep the counters.
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0answers
49 views

How can I configure iptables for per application setup?

I am working on a project where we are building lots of micro-services. Each service is neatly packaged as an RPM. Ideally I'd like for us to have iptables enabled on all of our machines and it would ...
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57 views

Why SAMP is not listening to the port

I have forwarded 38474 port to internal port 7778. Then I launched San Andreas Multiplayer on my CentOS server. When I'm typing netstat -npl I see this: Proto: tcp Recv-Q: 0 Send-Q: 0 Local Address: ...
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1answer
453 views

Curious about strange ICMP type 3 code 10 traffic to my IP address

My firewall (iptables) logs some strange ICMP type 3 code 10 traffic that I am curious to understand (specifically how or if this could be an exploit of some sort). Type 3 = Destination ...
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168 views

Forward local port to remote port in a Vagrant machine

I have MySQL running on my local machine and I need to publish this port to a Vagrant box without any special SSH hackery. Is there a way for me to forward 10.0.2.2:3306 to 127.0.0.1:3306 on the ...
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2answers
17k views

How to ensure SSH port is only open to a specific IP address?

This is my /etc/sysconfig/iptables: It has two ports open 80 apache and 22 for ssh. # Firewall configuration written by system-config-firewall # Manual customization of this file is not recommended. ...
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0answers
94 views

Redirect shared internet to tor/privoxy [closed]

I have shared my internet and set my client gateway to my IP, every thing works. I need to client goes through tor. I configured privoxy to use tor and with this iptable command I defined a rule: ...
2
votes
1answer
778 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 ...
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0answers
222 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, ...
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1answer
65 views

how to get effect of IP rules script in RHEL 6?

I have written one ip.sh file in that I have written one rule and then saved the iprules with the corresponding commands. Now when I opened /etc/sysconfig/iptables nothing is reflecting. I need the ...
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70 views

ISC DHCP Server - A Client's Uplink Is Not Working

Running a DHCP server, client(s) does not have up-link (0Mbps) and has a downlink (50Mbps.) I am setting up a gateway/router on a PC running Debian Wheezy with ISC-DHCP. I have 1 WAN (eth0) and 2 LAN ...
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239 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 ...