iptables allow creation of rules to define packet filtering behavior.

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165 views

How to replace udp packets on the fly

I've used iptables to reroute traffic to netsed like this, but it seems to route the traffic to another location. I've used hexinject like this: hexinject -s -i eth0 -c 1 -f 'arp' | replace '06 04 ...
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1answer
268 views

How to route traffic through different proxy servers based on destination

Background I work on a corporate network that is behind a proxy server. I also work with some remote sites that I am able to access via a bastion / jump host ssh proxy. In my ~/.ssh/config I have a ...
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2answers
99 views

Best practises: Applying iptables firewall rules for SSH

I need to add some firewall rules in our QA environment using iptables. I have to do the changes remotely . Some of the changes also include disabling SSH for few Networks . What are best practices ...
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64 views

Incoming internet SSH traffic to eth0 and outgoing internet traffic to wlan0

I have this setup: kali linux on raspberry PI connected to eth0 and wlan0. eth0 has internet access and public ip with port 22 open. wlan0 has internet access. I want to be able to connect to my ...
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1answer
52 views

Iptables dropping HTTP 302 packages contain suspicious domain string

The HTTP 302 packages I want to block have: Header HTTP/1.1 302 Found Location: ...
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1answer
114 views

Open port on one IP

I have spent all day looking this up with no luck. So, I own the IP range xxx.xxx.xxx.xxx/27 and I want to open port 22 on IP xxx.xxx.xxx.66 yet close port 22 on all others, then open port ...
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1answer
264 views

What order are mangle dscp rules applied with iptables?

I'm using iptables mangle to mark traffic with different DSCP values. I'd like to confirm the order in which overlapping rules will be applied. I assumed that the logic would be the same as with ...
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1answer
421 views

Why does iptables accept packets on a given port, when it is closed?

Here is my situation. I have a public address on my router and have manually forwarded a given port for torrenting, so not via UPnP, that is disabled both in the router and the application. It works ...
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1answer
272 views

iptables: command not found - CentOS 5.5

I am using CentOS 5.5. I want to add new IP in my iptables. But I cannot do it. Tried everything with 'iptables'. The latest version of 'iptables' is at sbin. I'm in 'sbin' directory. But it says ...
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2answers
163 views

How can I silently drop some outgoing packets?

I'm doing some testing of an application I am working on, and I need to be able to silently drop outgoing UDP packets for a short period of time to replicate a possible failure mode. Is there any way ...
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1answer
81 views

iptables nat not work for sctp

i have a server in internal network and i want to access it from external. the network is like this: Server A (132.196.28.229) is in external network Server B (10.35.202.24) can access both network ...
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1answer
254 views

IPTABLES - Bad IP Address

I am trying to turn my Raspberry Pi into a VPN server. To do this I am following this tutorial. The only issue is when it tells to to run this command iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o ...
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48 views

Detect which program is blocked by firewall

The linux firewall can show a lot of information in the LOG target, for example via --log-uid. How can the executable doing the network call be logged, too? I did not find anything in the FAQ, the ...
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137 views

Raspberry Pi OpenVPN SSH problem

I followed this tutorial to configure OpenVPN and it and runs very well: http://blog.frd.mn/raspberry-pi-vpn-gateway/ Now I want to access my Raspberry Pi via SSH. OpenVPN is most of the time ...
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1answer
200 views

How to set up a clear SuSE-Firewall?

I’m doing some rules in a machine with the firewall disabled, but when I run rcSuSEfirewall2 a lot of rules and policies are applyed by default: iptables -L Chain INPUT (policy DROP) target prot ...
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1answer
294 views

ufw won't allow connections to port 5432

I've installed Postgresql 9.4 on Ubuntu Trusty from the PGDG ppa. I've created a database and set it listen-addresses to '*'. I've made an entry in the pg_hba.conf file. I can connect locally with no ...
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287 views

Use iptables to redirect **all* requests, even DNS-unsolved domain?

Context: With iptables, I redirect all the traffic - incoming at port 80 - to a distant server IP (X.X.X.X). I aim that anywhat you write in the urlbar of browser, you get X.X.X.X. IP That works ...
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1answer
582 views

forward all mysql traffic to a ssh tunnel

I have a local application that needs to connect to a remote mysql server at 40.40.40.40:3306 The main firewall blocks all connections but ssh, I can set up a ssh tunnel and connect to the server ...
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1answer
82 views

Per user routing on wifi

I'm using vpn but i want to have one user that could access network not through vpn but using my real ip address. The problem is that all solutions i found by quick google'ing, for example this ...
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1answer
76 views

iptables and ssh

I'm running Arch Linux and I have a running SSH daemon to access my machine when I'm out side my LAN. I can do the connection, but iptables keeps blocking SSH Daemon, so I can only connect if I turn ...
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1answer
37 views

iptables rules' weird behavior

I have a set of iptables rules (see below) whose purpose is to disallow traffic to go out of my machine when my VPN connection is abruptly lost or manually terminated: #!/bin/bash echo "Please wait ...
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0answers
40 views

RHEL 6 IPTables filtering of IPSEC protected Traffic

looking for some guidance to make sure I'm going in the right direction and maybe get some hints or gotcha's I need to be thinking about. I'm working on RHEL 6.4. I have a cluster of computers that ...
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1answer
172 views

Why doesn't NAT reserve ports from the machine's TCP and UDP port pool?

I made two experiments. This is the network for both of them: [private network] [public network] A -------------------- R ----------------- B 192.168.0.5 192.168.0.1|192.0.2.1 ...
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1answer
256 views

Default gateway is not reachable

I have a vmware player on which i have installed CentOS 6.5. And on that CentOS 6.5 i have installed lxc and on that lxc i have installed centos 6.3. I am using NAT and bridger as a Network adaptor ...
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1answer
56 views

Is it possible to reduce information in iptables log?

I noticed that there are data in the iptables log that I don't need, so I was wondering if it's possible to change some configuration so that the log has less information, thus reducing the log's ...
2
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1answer
250 views

Rewrite source IP in TCP replies using iptables

I'd like to rewrite the source IP on TCP/514 traffic leaving a redhat machine, for connections that weren't initiated from the machine. The machine receives TCP/514 traffic on an interface, for ...
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57 views

server1 ssh's to server2 but server2 sees server1 by it's private ip due to both servers being on the same firm/network

I ssh into server1 via it's public IP from server2. I then ask server1 what my IP is. i.e. server2's IP. It shows me server2's private IP. I want it to show me server2's public IP. If server2 was ...
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1answer
156 views

Apache VirtualHost redirect 302 (cyclic link)

I seek some wisdom, so please help... I have one VM acting as router/web server/dnsmasq server on IP: 192.168.100.1. And I have other machine acting as client. Server has IPTables rule to redirect ...
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1answer
329 views

iptables - how to drop protocols [closed]

I have the desktop-server Debian Jessie machine running for testing purposes just for 19 hours now. I have already set a few rules as you can see above. But I am not really into networking. So it ...
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0answers
163 views

iptables: block communication with others in same subnet

I have a couple of devices in my subnet (e.g. 192.168.0.0/24) and would like to make sure that one of these devices (identified by MAC or IP) can only talk via the router (where I'd like to set up ...
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3answers
388 views

Why do some TCP reset packets show up in my iptables log?

I started to add some basic iptables rules on my Debian Jessie server. My objective is to filter and log network traffic (for security and learning purposes). Disregarding ICMP packets, these are ...
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1answer
85 views

Who's messing with my router?

Recently, I've been feeling that somebody is doing bad things to my Access point. My wifi access point is "protected" with a hidden ssid, and a WPA2 password. Nobody granted access apart from me, ...
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260 views

How to build via iptables an transparent reverse proxy

I just use an Server with an public ip X.X.X.X to redirect without (changing the header ip) to another public ip Y.Y.Y.Y and the same back. My backend server is windows 2012 r2 and my proxy server is ...
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1answer
54 views

What do the numbers in brackets mean on the iptables-save output?

What do the [368:102354], [0:0] and [92952:20764374] in my iptables output file mean? :INPUT ACCEPT [368:102354] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [92952:20764374]
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1answer
575 views

iptables - why do I get “Table does not exist (do you need to insmod?)”

I need to install some iptable ruels to block traffic that originates from a certain country, I found this script example on http://www.cyberciti.biz/faq/block-entier-country-using-iptables/ it works ...
2
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1answer
83 views

Iptables rule to drop packets to and from local network

I want to set a virtual machine on laptop, but I don't trust the guest system fully, so I would like to block it's access to local network (to network 192.168.0.1/16 or 10.0.0.1/8 or ... the other one ...
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2answers
34 views

How to use routing to use the next available inetface

My system has 2 interfaces (eth0, eth1). I open a socket and bind it with an ip attached to eth0, now I want the OS to route the packets to another ip (which attached to eth1 but i'm not sure it's ...
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147 views

openvpn: iptables not forwarding

I have the following topology: And I'm following the iptables rules listed on https://community.openvpn.net/openvpn/wiki/BridgingAndRouting Here's the output of iptables -L -v Chain INPUT (policy ...
2
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1answer
446 views

Local port is not accessible with public IP address

I have a linux server which has public IP and Private IP. So, when ever I login with public IP, the terminal directly shows private IP. example: $ ssh root@55.27.XX.XX root's password: ...
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1answer
26 views

installed application keeps open port

I installed an application (a text editor) and it keeps a connection alive. I blocked the IP with iptables, but the port stays open. netstat shows: tcp 0 0 127.0.0.1:<port> 0.0.0.0:* ...
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75 views

Routing only VM traffic through VPN

I'm stuck on a problem and would like some help if possible :-) My goal is to make my VM going through my VPN connection and my HOST through the standard gateway. Configuration : VM (192.168.100.1) ...
2
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1answer
296 views

iptables rule in /etc/rc.local are not loaded

/etc/iptables.conf contains a rule to dump my outgoing packets to 10.199 network as, *filter :INPUT ACCEPT [122:9273] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [73:8165] -A OUTPUT -d 10.199.48.0/24 -j ...
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2answers
125 views

traffic routing with DNS

I have 2 gateway machines. 1 debian (main - 192.168.1.1), 1 centos (backup 192.168.1.2). There are 2 networks, 1 LAN and 1 WAN, going through "main" and from there over ISP1 "backup" is on LAN and it ...
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47 views

How to drop packet if conntrack entry not present

Is there a way to check if conntrack exists before doing a particular action in iptable chains ? I would like to drop the packet in mangle-postrouting if conntrack entry is not present, dont want it ...
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1answer
57 views

CONFIG_NF_CONNTRACK is not set

I am trying to setup iptables on udoo quad but I hit a brick wall and cannot find a fix anywhere: root@udoo:/# uname -a Linux udoo 3.0.35 #10 SMP PREEMPT Wed Jul 30 18:16:10 CEST 2014 armv7l ...
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1answer
219 views

iptables do not work, very slow to process on Debian 8

I never had issues with Debian 7 using iptables. However, with Debian 8, I cannot get iptables to work at all. Simple script like this takes several minutes to load and can't access my portal page. ...
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24 views

PPTP IPs different than LAN ips

in /etv/pptpd.config I have: localip 1.0.0.1 remoteip 10.0.0.100-200 my server real IP is 192.168.1.40 (my LAN is 192.168.1.0) is it OK to do it? how I can route it so the clients with ...
2
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1answer
141 views

route some traffic in subnet to other gateway

I want to route traffic destined for 192.168.5.0/24 to a gateway of 10.1.10.24, but all other traffic to a gateway of 10.1.10.1. I tried: ip route add 192.168.5.0/24 via 10.1.10.24 but it seems to ...
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2answers
218 views

Using IPTables to Block Ports to Class A Subnets While Allowing Web Ports (80/443)

This is about a cPanel server which, like most servers, is under constant attack from lands afar. Considering that I only host to clients in the US and Canada, there is less of a reason to allow full ...
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1answer
41 views

How to find what custom config is used by iptables?

I need to open the custom iptables config, and change old IP address to new. How I can find what custom config is used by iptables?