iptables is the userspace command line program used to configure the Linux 2.4.x and 2.6.x IPv4 packet filtering ruleset. It is targeted towards system administrators. Please, when asking a question about iptables, add the output from the following command: iptables -L -v -n

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2
votes
1answer
47 views

Find source of outgoing traffic to specific UDP port [duplicate]

Since a few days ago I've been observing some strange recurrent outgoing UDP traffic from my server on port 24441 but since it's not constant, I cannot seem to find what's causing it. All I can see ...
2
votes
0answers
13 views

Policy-based routing on OpenVPN server

I'm trying to set up an OpenVPN server as reverse proxy for mobile/desktop devices, that can relay traffic based on certain policies: only requests to white-listed IP addresses are going to be ...
0
votes
0answers
47 views

iptables requires POSTROUTING for port forwarding

I have a very basic router/firewall running Ubuntu. I want to forward tcp connections on a specific port (443) to one of the machines in the local network. It has one interface to the outside world ...
-1
votes
1answer
32 views

ip tables, block all traffic to a specific ip, unless it comes from a specific ip

Here's the situation. I have multiple Apache vhosts listening on port 443 on different IPs, on the same network interface. I would like to only allow a certain IP to access one of those vhosts. In ...
1
vote
1answer
54 views

unable to connect to ubuntu on port 3306 (mysql) on rackspace instance

I'm trying to connect to port 3306 on an Ubuntu box and am unable to do so. When I do iptables -L -n | grep 3306 I see this: ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:3306 ...
3
votes
1answer
49 views

How to configure collecd aggregate plugin to aggregate output from IPTable::Plugin?

I have enabled the CollectD:IPTables plugin to track traffic to two different server groups: LoadPlugin iptables <Plugin iptables> Chain "filter" "TRACK_TRAFFIC_SERVER_A" ...
1
vote
1answer
20 views

Create subzones in firewallD

In firewalld, I can assign a zone to an network interface. A zone contains some firewall rules. Now I have a network interface with different levels of trust (172.16.1.1/32 should have special ...
0
votes
0answers
30 views

Linux policy routing based on transport protocol

Is it possible to specify transport protocol, in my case SCTP, with Linux ip command, in order to do some policy routing? Edit: What about marking those packets with iptables and then routing them ...
0
votes
2answers
28 views

Iptables NAT (PAT) A to B to C and back

I want to access via SSH a DB server from an outside network via a linux (CentOS) gateway with two interfaces in separate networks as it follow below: Admin PC IP: 10.21.1.8 Linux GW IP eth1 ...
-3
votes
1answer
43 views

Difference between iptables rules and firewall rules?

I am renting a vps and the company I rent from has firewall settings where I am allowed 20 rules. Then I have the iptables on my server. I have just setup some rules on the iptables that I found from ...
1
vote
1answer
156 views

Why is iptables not blocking any ports?

I have iptables running and the most recent rules applied (i.e. I restarted the service and it says everything is "OK"). I have only used system-config-firewall to edit/define any rules, so I ...
-4
votes
2answers
62 views

Where do the Chinese, Russian and etc. random attackers find their targets?

I recently started running a personal site on a dedicated server that i've had for some time, but have never actually used. I have never checked it's logs, but now when i do, auth.log is full with ...
1
vote
0answers
48 views

Route 172.0.0.0 and 10.0.0.0 traffic through two NAT boxes

I have set up two NAT boxes in two separate AWS accounts and given the necessary security group permissions to allow both instances to talk to each other. In account A I have a service that needs to ...
3
votes
1answer
119 views

Windows 10 strange OpenVPN behavior

I have an OpenVPN server running (93.xxx.xxx.xxx is the public IP) to which different android and windows clients can connect and have access to the internet, but an OpenVPN client on my Windows 10 PC ...
9
votes
2answers
316 views

iptables is converting the IP into a domain

I'd like to block an entire set of IPs on the server: iptables -A INPUT -s 77.0.0.0/8 -j DROP Though when I run iptables -L on that record I get a strange domain instead of the IP DROP tcp ...
-1
votes
2answers
33 views

Can't open new port in iptables

Today I'm facing a strange problem. Some days ago I configured Iptables. I opened port 80,1000 and some others port. Today I need to open port 25 for mail system. I have added the rule in ...
0
votes
0answers
12 views

netcat relay mirror for arbitrary protocol number

How can I set up netcat to listen for incoming packets on protocol number 150 and send them back (to the source IP of the packet) with the same protocol number? So, everything that arrives on the host ...
1
vote
0answers
23 views

iptables mark is not persisting after MASQUERADING [closed]

iptables -i eth0 -t mangle -I PREROUTING 1 -m mac --mac-source $mac -j MARK --set-mark 88 echo "1" > /proc/sys/net/ipv4/ip_forward iptables -A FORWARD -i wlan0 -o eth0 -m state --state ...
4
votes
1answer
105 views

Whitelisting outgoing traffic from docker containers

I have a server running multiple docker containers in the following configuration: One of the containers is a reverse proxy binding to the exposed ports of the other containers. This is the only ...
0
votes
1answer
46 views

Iptables configuration in CentOS for GCM commands

I am planning to enable iptables for my CentOS VM. Have configured the below rules. But for GCM (Google Cloud Messaging) commands it fails to receive reply from GCM server. If i disable iptables it ...
0
votes
0answers
39 views

blocked connection to the ts server under OpenVZ

I have virtual machine with Ubuntu 12.04 under OpenVZ. Teamspeak server v. 3.0.11.4 All ok if i connect from LAN or subnet of my provider. But outside traffic blocked. eth1 - LAN interface of ...
0
votes
0answers
19 views

Redirect external ip of server to external ip of virtual machine

I have a server with multiple virtual machines. Let's say this is my server ips: Internal 1.2.3.4 External 5.6.7.8 Now, if i go to 1.2.3.4:8082 it goes to my app (I redirect :8082 to de internal ip ...
1
vote
1answer
46 views

Best practice for managing a whitelist of ips across multiple servers with iptables?

I was wondering what the best practice for managing a whitelist of ip address across multiple servers? We want to allow our user base to add an ip address they want to whitelist through a web ...
0
votes
0answers
13 views

iptables forward traffic from specific port to secondary interface

Have a machine1 with 2 interfaces: eth0: 10.123.111.48 eth1: 10.123.111.52 machine2: eth0: 10.123.110.63 eth1: 10.123.110.24 There is a valid route from machine1 eth1 to machine2 eth1 for port 3306, ...
0
votes
1answer
61 views

iproute rt_table and mark not working on linux

I have this configuration which comes from official and unofficial guides and questions readings here and a lot of failed tests. CentOS 7 and Ubuntu server 15 (LAMP and only eth0). ...
-4
votes
3answers
75 views

If no service is listening on a port can a system still be accessed using that port? [closed]

If I have a linux server with a FW rule (iptables) to allow inbound to a particular port does a service have to be running and listening to accept that connection or is there another way to access the ...
1
vote
1answer
36 views

Iptables max number of ports you can specify with --dport that is not continous?

How many ports can be specified in a single rule using the --dport argument?. Ex - iptables -A INPUT -p tcp --dport {0,5,10,15,20,25, etc,,??} -j ACCEPT
1
vote
2answers
32 views

IPV4 linux networking configuration

I am having problems figuring out what I configured wrong. I can't get packets back from the velodyne onto a Fedora server with 2 eth interfaces em1 and em2. I have velodyne connected to em1 host to ...
0
votes
1answer
38 views

Ways to reduce packets per second (Bundle VPN Packets?) [closed]

I have an ISP that blocks me when I do more than 10 pps on any port. Only exception: ports 80 and 443 where I am allowed 100 pps. To avoid being blocked I can use a VPN on port 80 or 443 which then ...
1
vote
0answers
10 views

Anomalous iptables entry with fail2ban (is it misconfigured to block outward traffic?)

Overall we are very satisfied with fail2ban as it has accumulated several dozen neverdowell IP addresses in our iptables rules. However I notice the following rule has also appeared: Chain ...
1
vote
1answer
140 views

iptables route PPTP VPN through polipo http proxy

I want to route http traffic of my local pptp server to use Polipo http_proxy. So i found this QA : IPTABLES: routing VPN users through transparent Squid but i test on my system & change iptables ...
-3
votes
1answer
29 views

Restrict a range of ports to one IP except one

Is there a way I can allow a range of ports to only be used by one IP address but one? Thanks. Precisely, I want to restrict range 6011-6099 excluding 6012. The rule to restrict the range 6011-6099 ...
2
votes
1answer
18 views

Problems Configuring IPTABLE for Samba Share

I am trying to configure Samba on my CentOS 6 server such that only 3 IP addresses have access to the Samba Share. For some reason my iptable configuration is wrong. I have checked lines 11-15 and ...
-1
votes
1answer
93 views

Centos iptables: No chain/target/match by that name [duplicate]

I had a CentOS6.7 with OpenVZ. Now, I just uninstalled OpenVZ and start using Plain CentOS6.7. Due to some difficulties for using cPanel in OpenVZ. I noticed one problem when install csf in my plain ...
0
votes
1answer
26 views

SNAT& iptables in Centos

i have a remote server where I have added a new FAILOVER IP in a new interface, ETH0:0. Everything works perfectly; IP is setup. I want the traffic that is coming from ETH0:0 to use the ETH0:0 as the ...
0
votes
0answers
24 views

Linux forwarding packets to remote destinations (not localy)

Network case: Source--Routers ... eth0=LINUX=eth1 ---- some routers.. -- Destination 2.2.2.2 10.0.0.1 192.168.0.1 1.1.1.1 and 1.1.1.0/24 via ...
0
votes
1answer
31 views

iptables error with No such file or directory

I have CentOS 6 x86_64 vps server. I just created the following iptables. But it gives an error message. What am I doing wrong here? *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ...
1
vote
1answer
33 views

nat and xen, nat only to external ip

I've setup xen that way that all my vm's have a public ip and a private ip (192.168.0.x). However, those vms which don't have a puplic ip should also get internet access so I did setup nat. iptables ...
0
votes
1answer
29 views

FTP EPSV command and iptables

Troubleshooting an issue with an FTP connection going through an iptables firewall and seeing some strange issues with passive mode. We are trying to connect to an FTP server and get the directory ...
0
votes
2answers
62 views

How can I use NAT or haproxy to reroute a certain host name?

I have an infrastructure where all requests made by internal subnets have to pass through a server in the "open to the world" subnet, where my NAT instance is (I'm using AWS). I want to create a host ...
0
votes
0answers
29 views

Need to redirect traffiic from the tap interface at0 crated by airbase-ng to apche2 server runing on my localhost 127.0.0.1:80

My dhcp config file /etc/dhcpd.conf authoritative; default-lease-time 600; max-lease-time 7200; subnet 192.168.1.128 netmask 255.255.255.128{ option subnet-mask 255.255.255.128; option ...
-3
votes
1answer
41 views

Redirect all websites to a single webpage using iptables

I have a router which runs busybox, it has iptables so i wanted to redirect all webpages clients request to a single webpage. I cant use hosts file because the /etc folder is mounted as read-only. Is ...
0
votes
0answers
34 views

Internet from AWS Private Subnet Instance Not Working

I created on AWS a VPC with a private and a public subnet. I launched an instance from the private subnet and I would like to access the internet through the NAT server. Disabled the ...
1
vote
0answers
76 views

Drop first packet for every IP with iptables

My servers are getting UDP-flooded with spoofed source IP addresses. They flood with real user packets so I cannot rate limit or block these packets. Is there a way to drop the first packet received ...
3
votes
0answers
87 views

iptables is occasionally logging MAC addresses. Why?

I have logging enabled on specific iptables packet drops. The rules I'm using are IP/port related only and this is what I can easily see in the logs, however occasionally I do get MAC address ...
1
vote
1answer
30 views

iptables - Filter by MAC on FORWARD chain

I need to setup a firewall between a server, and the clients on the intranet that filters access by MAC on the FORWARD chain. The server has one NIC (on subnet 10.0.0.0/29), the firewall two NICs ...
0
votes
0answers
20 views

Why iptables is not logging

I have the iptables configuration below. I want to block all input but accept some rules. But I want to be able to log the droped connections. But it's not logging. I have this: iptables -N ...
-1
votes
1answer
78 views

Redirecting all outgoing HTTP traffic from one computer to another on a DD-WRT router

I am trying to debug some HTTP traffic from one computer (let's call it A) on my network. I would like to redirect all of that traffic to another computer (let's call it B) without changing any ...
0
votes
1answer
50 views

Where are iptables rules stored on Digital Ocean Ubuntu 14.04

I have a basic standard Ubuntu 14.04 droplet on digital ocean. I used ufw to set some firewall rules but forgot to open port 22 for SSH. I rebooted my server and could no longer log in so DO support ...
0
votes
1answer
78 views

multiple tuntap VPN traffic selection

I have a php / bash application on top of a linux machine (centos or debian but assume redhat just in case the reply need different dialect) connecting to port 80. Actually I'm perfectly able to open ...