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

learn more… | top users | synonyms (1)

0
votes
0answers
7 views

iptables with buildroot unknown option --set-mark

I'm trying to determine which buildroot config options are required in order to access the --set-mark option in iptables. I've gone to the extent of selecting nearly every networking, iptables, and ...
0
votes
0answers
34 views

OpenVPN not working with UDP but working with TCP

I am running OpenVPN server on Ubuntu 14.04.3 and my OpenVPN client is on Raspberry Pi. When I use protocol TCP, then I can ping to server on ip 10.8.0.1 but when switch to UDP protocol, I can't ping ...
3
votes
1answer
36 views

TFTP: transfer time out on RHEL 6 server

I am hitting a wall here trying to get tftp to work using RHEL 6 as a server. The error, from the client, is simply "transfer timed out". On the server, I can see udp 69 traffic coming in from my ...
-1
votes
0answers
13 views

Routing packets from one interface to another while leaving untouched the default interface

I have a Raspberry Pi box with the following physical network interfaces: eth0 - built-in Ethernet, connected to my router's LAN wlan0 - built-in wlan, also connected to the LAN but unused wlan1 - ...
0
votes
0answers
12 views

iptables: how to configure ip:port package forward?

I want to configure server (10.100.1.138:10000) as a jump server(which iptables server), all request to 10.100.1.138:10000 will forward to another public web-site (such as 111.13.101.208:80), and I ...
0
votes
0answers
19 views

(D)DoS Detection within linux and IPTables

We currently have a hardware firewall running on Ubuntu 14.04 on a 10Ge network. We use this to filter traffic and attacks, this is all working great and we have blocked quite a lot of DNS/NTP attacks....
0
votes
2answers
41 views

monitor traffic at the scale of millisecond

I have several linux servers running Ubuntu 14.04, and turned them into a Spark cluster. At this point, I want to measure the network flow between the servers, at the scale of milliseconds, in order ...
-1
votes
3answers
65 views

Can not connect to the host itself

Well, the problem is simple. I have the site based on apache and trying to execute cron job at this site from the same server. Let's say my site http://example.com and cronjob is /usr/bin/curl http:/...
-1
votes
2answers
20 views

Iptables not working with policies drop and state [on hold]

I configured iptables with the following rules, but something is blocking access to port 80 iptables -P INPUT DROP iptables -P OUTPUT DROP iptables -A INPUT -i eth0 -p tcp --dport 80 -m state --state ...
-1
votes
0answers
11 views

mail server behind ubuntu iptables router [duplicate]

I want to run a mailserver behind an iptables router. I set up the router with ip-forwarding on Ubuntu 16.04 Server edition. I enabled ip-forwarding in /etc/sysctl.conf . I have set net.ipv4....
0
votes
0answers
27 views

smtp-request behind iptables-router not working

I set up a router with ip-forwarding on Ubuntu 16.04 Server edition. I enabled ip-forwarding in /etc/sysctl.conf . I have set net.ipv4.ip_forward=1 and executed sysctl -p /etc/sysctl.conf I used ...
-1
votes
0answers
21 views

Unable to elinks or Ping sites after starting IPtables service

Good day! I hope you can help me. I know how to add basic iptable rules but I don't know how to add rules for the following setup. Below are my host details: HOST01 - with Squid(port 3128) for ...
-1
votes
1answer
14 views

Name of the tun interface when running openvpn?

I have two OpenVPN client setups, controlled by systemd services openvpn.foo and openvpn.bar. They connect to different VPNs and may or may not be active at any point in time. I'd like to set up ...
-1
votes
1answer
15 views

Local Port Forwarding does not work when only port 22 is allowed by Iptables

I'm trying to perfom a Local Port Forwarding using SSH tunneling. Machine 1: the rules of iptables are: Chain INPUT (policy ACCEPT) target prot opt source destination ...
0
votes
1answer
36 views

How to block 111 udp port via iptables?

I've got an issue related to block 111 port only for udp. For tcp it was blocked without any problem. This port is used by application rpcbind. I test it via netcat. This is my iptables. It contains ...
0
votes
1answer
26 views

Forward port and keep source IP

I have a system with a static IP address running several LXC containers. I can communicate with the containers over an interface as it would be a physical machine. One of this containers is a postfix ...
1
vote
1answer
26 views

What is correct iptables chain to put -j NETFLOW

I have a router, with firewall (with drop policy), nats, services. I want to account all factual traffic (inputed before firewal, outputed by services, and passed firewall in forwarding), with its "...
0
votes
1answer
38 views

Unable to connect to OpenVPN server from devices that are in same network than the VPN server

I have Open VPN server to which I can connect from devices from the Internet but I can not connect to the VPN server from devices that are in the same network where the other end of the VPN server is ...
0
votes
0answers
89 views

iptables redirect packet nat

We currently run the following iptables rule: -A PREROUTING -d DSTIP -p udp -m udp --dport DSTPORT -m u32 --u32 "0x0>>0x16&0x3c@0x8=0xffffffff&&0x0>>0x16&0x3c@0xc=...
1
vote
1answer
39 views

Configure iptables on linux ubuntu to route only specific IP between two networks

I'm not a linux expert and I need to setup this scenario. I've an Hyper-V host where I have two virtual network interfaces, both of them are added to a linux ubuntu machine, eth0 and eth1. Now I ...
2
votes
1answer
77 views

How to exclude lan from routing

server1 - eth0 - 192.168.1.212 (192.168.1.0/24) - eth1 - 192.168.5.1 (192.168.5.0/24) --> router2 --> DSL server2 - eth0 - 192.168.1.223 (192.168.1.0/24) - eth1 - 192.168.123.223 (192....
0
votes
1answer
17 views

Ubuntu 12.04 server cannot access anything outside

My Ubuntu 12.04 server was working fine a few days ago. But today I couldn't access anything outside. And i cannot ssh to my server neither. I am directly plugged into the console through my vps ...
2
votes
1answer
28 views

Rule of fail2ban not working when the request is from the brute force attack

I have a situation where some IP from moldova try everyday discover my basic auth credentials with some type of brute force attack. However I have a rule with fail2ban that should avoid this ...
1
vote
0answers
25 views

iptables - POSTROUTING / SNAT doesn't change source IP (two routing tables)

I have a problem with iptables POSTROUTING rule, it seems that SNAT rule doesn't change source IP address. I would like set up the following system to route all traffic from LAN 2 through a VPN tunnel....
2
votes
0answers
17 views

Iptables don't load balance

I have consulted multiple tutorials to achieve load balancing over two internet connections. However, all traffic continues to get routed over the default route with the lowest metric, and I can't ...
2
votes
1answer
43 views

Trouble with nginx and PHP-FPM

I am having trouble getting my webserver (nginx) to work with php-fpm. The page keeps loading and then the loading time expires. I hope one of you can help me resolve this issue. I have made an ...
3
votes
1answer
569 views

What is the windows server equivalent of iptables?

I found this post however it is outdated and appears to be focused on consumer versions of Windows. What is the Windows Server 2012+ equivalent of iptables?
0
votes
0answers
29 views

Best way to throttle aggressive clients on LAMP server using iptables?

I've found two ways to do this using iptables. One is using the recent module: iptables -A INPUT -p tcp --dport 80 -i eth0 -m state --state NEW -m recent --set iptables -A INPUT -p tcp --dport 80 -i ...
1
vote
1answer
16 views

UFW 0.35 - Redirect incoming port 2121 to port 21 on VM (other interface)

I'm posting here because I've got a server, and I want to redirect the port 2121 of my main interface (eth0) to the port 21 of my secondary interface (virbr0). This is my configuration : Physical ...
0
votes
0answers
12 views

How to redirect traffic every time when service hostapd is started?

I have been using iptables to redirect all traffic to remote host on port 80 towards my local proxy 127.0.0.1:8080 for testing. I used iptables -n nat -L to check if iptables is set. sudo iptables -t ...
-1
votes
2answers
28 views

Iptables not working on a bridged setup [closed]

I am trying to block DNS requests using an Ubuntu machine. I have created a bridge and the packets are being forwarded as expected. Only when I add iptables rules, it is not taken in account. I tried ...
0
votes
0answers
7 views

Symmetric NAT with IPtables - TURN

I need to configure symmetric nat on two linux based ( openwrt ) gateways . I want to check if my TURN server is working correctly instead of STUN. How to perform that with IPtables ? echo "1" >...
2
votes
0answers
37 views

WhatsApp call blocking

I'm managing a small network and I'm requested to block WhatsApp calls without blocking its messaging features. As they provide their public IP addresses I thought it'd be straightforward to add some ...
0
votes
1answer
44 views

Traffic is routed via unknown means

I have 2 machines running CentOS: Machine A has two NICs: 192.168.150.1/255.255.255.0 and 192.168.1.1/255.255.255.0 Machine B has one NIC: 192.168.150.2/255.255.255.0 Machine B is connected ...
0
votes
0answers
9 views

set transparent proxy for java socket server

I developed software of captive portal ,to redirect traffic of D-Link Router to my server port(8082) I had set iptables commands: sudo iptables -A PREROUTING -t nat -i eth1 -p tcp -m multiport --...
0
votes
1answer
29 views

Throttle incoming connections with iptables

I have a slightly self-inflicted DoS happening in some circumstances, and I'm trying to figure out if I can use iptables to help mitigate it. The short version is "How can I limit the rate of incoming ...
0
votes
1answer
14 views

Why do the numbers shown in ip_conntrack_count and conntrack -L differ

I noticed the following today on our router: user@router:~$ cat /proc/sys/net/ipv4/netfilter/ip_conntrack_count 28141 However: user@router:~$ sudo conntrack -L > /dev/null conntrack v1.2.1 (...
0
votes
1answer
60 views

How to figure out why my NAT-box sends TCP RST packets?

TL;DR: I see that an ubuntu (which I have an absolute control of) host sends a packet under certain circumstances. How to find the application/kernel module responsible for that packet? I am ...
3
votes
1answer
49 views

Docker containers don't have internet access until docker service restarts

I'm creating a bridge manually, with this command: docker network create --driver bridge --internal --subnet=172.20.0.0/24 br0 Then i start containers using that bridge parameter --net=br0 --ip=172....
0
votes
1answer
25 views

Is it safe to use only iptables for security?

I have 2 servers on different machines. First machine should send requests to second machine via tcp. Both machine have static ip addresses. Does it secure to protect this interaction between servers ...
0
votes
2answers
43 views

Fowarding IP Traffic without NAT (Ubuntu 14.04)

I've been setting up OpenVPN and all the standard guides I have been following suggest setting up iptables so that the VPN server performs NAT on the VPN clients: iptables -t nat -A POSTROUTING -s *...
0
votes
1answer
28 views

Understanding snat rule in iptables from openstack

This is less of an OpenStack question and more of an iptables question. Consider the following chain in the NAT table Chain nova-network-POSTROUTING (1 references) pkts bytes target prot opt in ...
3
votes
1answer
35 views

ipset behave differently when adding IP address from iptables and ipset command

I have a list that created below command ipset create foo hash:ip maxelem 40000000 timeout 180 This is how empty foo look like #ipset list foo Name: foo Type: hash:ip Revision: 1 Header: family ...
0
votes
0answers
18 views

iptables NAT with port forwarding

I have a Linux box acting as a NAT, with the following IPs: External network (eth0) - 128.123.xx.xx Internal network (eth1) - 10.1.0.1 (/24) I've got the basic NAT working, but now I need to forward ...
1
vote
1answer
54 views

IPTABLES - IP Restricted Port Forwarding for RDP

I can't find an answered question for this problem. I have about 7 ranges of IP address i would like to allow to RDP(port 3389) to a a server within my network. My main router uses iptables and i ...
0
votes
1answer
23 views

ip6tables blocking outgoing+incoming connections

i just changed to a server with ipv6 and therefore i changed my firewall script. Changing my iptables-script to ip6tables does not seem to work though. This is the ipv6 part which neither allows ...
0
votes
3answers
82 views

nginx docker container cannot see client ip when using '--iptables=false' option

I am using Docker 1.11.2 on Ubuntu 16.04. I am running several containers on my host which expose public ports, some should be only accessible by certain ip ranges, while others, like an nginx proxy ...
0
votes
0answers
24 views

split http/2.0 and http/1.1 TLS traffic with nftables

What is the correct nftables or iptables filter to detect TLS ClientHello messages that offer the h2 ALPN upgrade? After that i would want to map those TCP Connections to a different server locally.
0
votes
2answers
33 views

Obtain instance IPs behind ELB in order to add to iptables

What: We're using iptables and have our server rather locked down to only specific ports and IPs. Recently we have a requirement to open traffic to a third party service. However, the third party ...
0
votes
0answers
33 views

Are some of libvirt's default NAT iptables rules redundant?

To avoid my iptables scripts overwriting the rules set by libvirt for NAT, and to use my own DNS/DHCP server instead of dnsmasq, I had to manage my own virtual bridge instead of using libvirt's ...