1
vote
1answer
29 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. Type 3 = Destination Unreachable Code 10 = Communication with Destination Host is ...
2
votes
1answer
49 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 ...
9
votes
2answers
481 views

( /etc/sysconfig/iptables ) “Manual customization of this file is not recommended.” Why?

Editing this file directly /etc/sysconfig/iptables can save me so much headaches so much time and so on... and yet on the very top of the file it says.. Manual customization of this file is not ...
0
votes
1answer
31 views

Is it OK to copy /etc/sysconfig/iptables to another machine?

This is my original server with very loose security given that it does not block all ports via iptables. /etc/sysconfig/iptables contents: # Generated by iptables-save v1.4.7 on Mon Jun 16 ...
1
vote
2answers
46 views

Reject ssh connections made from proxies

I was seeing this question which was concerned with blocking access to the users who do not belong to a particular region. I am sure that blocking is possible but I see there is a workaround to this. ...
8
votes
6answers
155 views

iptables rule adviser script

There is a server without any iptables defense: ACCEPT all.. There could be custom applications on this server. If we should need to harden this server (so deny all, and only let what is needed by ...
2
votes
2answers
60 views

Temporary redirect ports

I need a temporary redirection of some ports to another machine. I've tried: iptables -t nat -A PREROUTING -p tcp --dport 4321 -j DNAT --to-destination 192.168.121.4:80 But shorewall blocks all ...
1
vote
0answers
46 views

How do I control ip routing in the new firewalld?

I have the following scenario: Our fedora server is connected to the internet on eth0 and has a second nic, wlan0 acting as an access point. The purpose of the access point is to provide a connection ...
4
votes
0answers
69 views

Why does my firewall (iptables) interfere in my bridge (brctl)?

I set up a bridge br0 "attached" to two interfaces: eth0, my physical interface connected to the real LAN, vnet0, a KVM virtual interface (connected to a Windows VM). And I have this single ...
2
votes
1answer
36 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 ...
2
votes
0answers
22 views

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 ...
1
vote
1answer
153 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
votes
2answers
56 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 ...
1
vote
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 ...
2
votes
1answer
31 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 ...
1
vote
0answers
87 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 ...
1
vote
2answers
59 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 ...
0
votes
0answers
100 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 ...
1
vote
1answer
81 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, ...
0
votes
1answer
254 views

Socket Connection Refused (raspbian) but ports are open for connections

I'd like to establish a connection between my client and raspbian. Within my network, I can connect to my service at any time without any problems. Now I want to connect to my service via the ...
0
votes
1answer
62 views

iptables correctness verification

I have so many questions around iptables and how it works. But we're using a modified kernel, and hence whatever experiment I try and fail, I can't be sure if it happens with Linux in common or just ...
0
votes
1answer
120 views

Iptables rule to allow only one port and block others

We have two apps running (on top of linux) and both communicates through port 42605. I wanted to quickly verify if this is the only port that's been used for communication between them. I tried below ...
0
votes
1answer
49 views

What does the last column in this IP table mean?

From a tutorial, I run $sudo iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT $ sudo iptables -L and get target prot opt source destination ACCEPT ...
1
vote
0answers
142 views

Corosync & Pacemaker IPTables Rules

When using Corosync with two rings via multi-cast addresses 226.94.1.1 (Port 5405) & 226.94.1.2 (Port 5406) what iptables rules are required to allow two nodes to communicate optimally without ...
1
vote
1answer
178 views

Webserver establishing new outgoing connections from port 443

I've been trying to configure the firewall on a webserver running Apache using iptables commands. I took the approach of blocking all outgoing connections, except for those that are required. ...
2
votes
0answers
112 views

IPtables rule to double NAT [closed]

Let me rephrase it.. I just need an IPtable rule to do double NAT-ting.. Host A - Host B - Host C - Host D Host B should do both source NAT and destination NAT, so that my request from Host A ...
3
votes
1answer
76 views

How does iptables recognize packet state?

Consider these two sets of rules: Set A -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT -A INPUT -j REJECT -A OUTPUT -j ACCEPT Set B -A INPUT -m conntrack --ctstate ...
1
vote
1answer
220 views

iptables forwarding between subnets

I want to forward traffic between two subnets, I'm not very familiar with iptables. The forwarding works except when iptables is enabled. There must be something wrong with the rules, though ...
1
vote
0answers
310 views

iptables and physdev match confusion

I'd like to be able to prevent a network bridge from generating certain types of traffic from some of its interfaces. If I understand iptables correctly, packets generate by a device appear on the ...
0
votes
1answer
204 views

iptables Port Forwarding — no service with the port

I have setup a network as in the image below: Firewall (FW) running CentOS 6 has two physical interfaces with subinterfaces: eth0:2 — 10.100.1.78/25 eth0:3 — 10.100.1.79/25 eth3 — 192.168.0.21/24 ...
1
vote
1answer
800 views

How to Block SSH Brute Force via Iptables and How does it work?

I'm planning to add the following rules to iptables to stop ssh brute force attack which are common these days. -A INPUT -i eth0.103 -p tcp -m tcp --dport 4522 -m state --state NEW -m recent --set ...
1
vote
2answers
995 views

FTP and iptables. Connection fails but ports are open

I installed proftp on my machine. With iptables disabled I can connect to the machine, using ftp-client or telnet. With iptables connection fails - telnet says "Connection failed" # works telnet ...
10
votes
1answer
584 views

Is it better to set -j REJECT or -j DROP in iptables?

There's an example of iptables rules on archlinux wiki: # Generated by iptables-save v1.4.18 on Sun Mar 17 14:21:12 2013 *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [0:0] :TCP - ...
1
vote
0answers
125 views

Portforwarding: router nat vs iptables [closed]

I would like to host some services on my pc and make them available from internet. (I'm aware of the security implications, it's more like a test for now). I don't have experience with iptables but I ...
2
votes
1answer
235 views

Understanding the iptables rules created by FirewallD

I am having a hard time trying to figure out what the iptables rules generated by FirewallD say. Focusing on the "public" input zone, I have the following rules: *filter :INPUT ACCEPT [0:0] :FORWARD ...
1
vote
0answers
30 views

How to send packets coming from a second router on a particular port back to the router, using iptables not a route

I have a Linux server which runs a particular service listening on a single TCP port. The Linux server connects to the internet using a PPP connection and also acts as router for a local network using ...
2
votes
1answer
257 views

No internet even with iptables ACCEPT all

I was trying to setup the firewall settings, and probably did something wrong. I don't have internet now unless I stop iptables service I tried flushing,and accepting everything sudo iptables -F ...
0
votes
1answer
259 views

iptables couldn't load target allow

I am using the command below to allow all traffic from hosts on my internal network but it says "iptables v1.4.18: Couldn't load target `ALLOW':No such file or directory". What is the problem here? ...
1
vote
1answer
286 views

Archlinux not configured with iptables

I have been trying to set up iptables on my archlinux server, however when I run iptables -nvL I receive the error iptables v1.4.20: can't initialize iptables table 'filter': Table does not exist ...
4
votes
1answer
87 views

How do you do NAT port redirection with PF?

In Linux, you can do NAT port redirection with a command like this: iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 8000 What is the equivalent with BSD's PF?
0
votes
1answer
152 views

iptables - why the stun, turn ports are not working to allow end points to access the server?

I have this iptables where all working except tcp/udp port 3478 and 5349. $ cat /etc/sysconfig/iptables # Generated by iptables-save v1.4.7 on Thu Nov 21 10:21:41 2013 *filter :FORWARD ACCEPT [0:0] ...
0
votes
0answers
507 views

Fail2ban - alternative robust for enterprise protection against DoS attack in SIP and similar to fail2ban features

Is there any fail2ban like software for CentOS 2.6.32-358.6.2.el6.x86_64 ? (fail2ban is 0.8.10 installed) but its slowing down the system completely, i was looking for something which can be similar ...
1
vote
0answers
255 views

destination IP mangle table

I have machine with 2 interfaces: eth1 connected to internet (ip xx.xx.xx.xx) eth0 connected to my laptop (ip yy.yy.yy.yy) I add those lines to the firewall file in order to manage the bandwidth ...
4
votes
2answers
390 views

fail2ban log parsing too slow on Raspberry Pi - options?

I'm running fail2ban on a Raspberry Pi at 950MHz which I cannot overclock further. The Pi is occasionally subject to SYN floods on particular ports. I've set up iptables to throttle the rate of SYNs ...
1
vote
0answers
118 views

Firewall config prevents hibernate connecting to postgres in CentOS6.3

I have an operating environment in CentOS 6.3 that has tomcat7 and postgres9.2 installed. There is just one web application deployed in tomcat that tries to establish a connection from localhost to ...
2
votes
1answer
131 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 ...
1
vote
1answer
237 views

how to investigate Firewall blocked outbound TCP

CentOS webserver with CSF (Config Server Firewall) running. Blocking all outbound / Inbound traffic except listed ports 80 81 22 21 etc. for web, mail & FTP services etc. I'm use to seeing heaps ...
0
votes
2answers
209 views

Isolate a hosts networking with iptables

I want to isolate a host on my home intranet using iptables on my linux router. So say for instance, I have a host that has the IP of 10.0.1.50 and I want it to be able to talk to the rest of the ...
3
votes
1answer
248 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 ...
1
vote
1answer
173 views

Intercept incoming TCP/IP packets on Linux and perform NAT

I want to make a decision of what computer is behind the firewall sending the packet. Imagine I have 2 PCs behind the firewall and I want to, based on (my algorithm), make a decision at the firewall ...