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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9 views

Docker containers connecting to a host daemon

I would like to run a daemon on the host and get the containers connect to it. I was thinking I will bind the daemon on the host to 127.0.0.1 and then have something (delegate? or is iptables enough?) ...
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0answers
13 views

OpenVPN server cannot ping client (routing/iptables issue?)

I am not sure exactly where the issue is here. I'm fairly sure that this is some NAT or iptables issue on the OpenVPN server but am lacking the networking know-how to fix the issue. The crux of the ...
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1answer
12 views

Configuring IPTables without connection tracking module

Usually connection tracking is required for outbound connections to allow established connections back in, for instance: iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT I don't ...
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0answers
12 views

Strange entries in Squid3 access.log

My WiFi network for guests is transparently proxied by Squid3. There's now a girl from Indonesia with her Samsung GT-B5330 running Android 4.0.4, who gets blocked by "The requested URL could not be ...
1
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1answer
48 views

iptables starts dropping packets; temporarily fixed by doing restart

I am running a small apache2/iRedMail server but I am having an issue with iptables. After a while of working correctly (hours) my server is unreachable on some ports (ports 80, 443 tested, edit: ...
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0answers
36 views

linux not replying to an arp request

I am running linux 3.14 on a system with 2 interfaces. on the first interface, i can access our local network. on the second interface, arp packets come in but linux doesn't send out reply. is it ...
3
votes
1answer
41 views

iptables-restore is creating dangerous rule

I'm having this definition file: *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [0:0] :Firewall-INPUT - [0:0] -A INPUT -j Firewall-INPUT -A FORWARD -j Firewall-INPUT -A Firewall-INPUT ...
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0answers
26 views

Access to alternative DirectAdmin port is removed from iptables after a while

First i installed csf. Then these auto block rules: http://help.directadmin.com/item.php?id=380 Next i opened a different port in csf for directadmin to listen to. Also added the exception to ...
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0answers
11 views

iptables fails between two NICs and 2.6.32.64 kernel

Until recently we used to split our WAN traffic and send it to two NICs (eth0 and eth1) apllying iptables: $IPTABLES -A OUTPUT -s $PRI -p tcp -m tcp -j MARK --set-mark 0x02 -t mangle $IPTABLES -A ...
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2answers
25 views

Iptables: Filtering string encrypted by ssl

I need to filter (send to BANRULES set) incoming http/https packets with a certain string (matchword). I do it easy when ssl is not in use (port 80): iptables -A INPUT -p tcp -m tcp --dport 80 -m ...
1
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1answer
48 views

When iptables is started, there is no ftp access because of timeout

When I start the iptables service, there is no ftp access because of a connection timeout. When I stop the iptables service, ftp works fine. This is the current iptables data: Update: replaced ...
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2answers
40 views

How to improve IP tables for web server [on hold]

this is my curreny /etc/sysconfig/iptables file for a webserver that must allow http, ftp and ssh access. *filter :INPUT ACCEPT [31395:4050333] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [30540:7083959] -A ...
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votes
1answer
48 views

Routing between two interfaces

I have a network 10.0.0.0/24, a gateway with ip 10.0.0.1. On the gateway there are two interfaces. eth0 Link encap:Ethernet HWaddr 08:00:27:a1:24:2d inet addr:10.0.0.1 ...
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votes
2answers
45 views

nmap port 3128 shows open but no squid running

Im trying to lock down an Ubuntu server and ran nmap -T4 against my server. Everything looks right except that it shows port 3128 open but I dont run a squid server or anything else I know of on that ...
1
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0answers
27 views

Configuring IPTables to exclude webhost from VPN tunnel [migrated]

I have a Raspberry Pi running as a server for my webhost. Raspberry pi is connected to a VPN service 24/7. Due to this, I am unable to connect to my webhost using my public IP address issued by my ...
4
votes
3answers
51 views

Block traffic behind AWS ELB

My web servers are behind ELB, I want to block traffic from some specific user agent which is a DDOS attack. Apache always see ip address of ELB as an end user so I tried below attempts: Blocking IP ...
0
votes
2answers
64 views

RHEL 6 Having issues forwarding port 80 to port 8080

I am trying to set up a JBoss app server on an RHEL build. Jboss is bound to 127.0.0.1:8080, and I am trying to setup iptables to redirect all traffic from port 80 to port 8080. This is my config ...
3
votes
1answer
25 views

How can I run a shell script on a snort alert?

I have snort listening to the SPAN port of a cisco switch. I'd like to be able to add an iptables DROP rule on my webserver for specific snort alerts but having a hard time finding out exactly how to ...
1
vote
1answer
50 views

Redirect all traffic from multiple interfaces to single IP

I would like to redirect all traffic (specifically TCP & UDP) from multiple WAN interfaces (ppp0, ppp1, ppp2) to a single IP from eth0. When it comes to interface to IP, I can use the PREROUTING ...
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0answers
22 views

Slackware internet gateway with iptables / poor browsing performance [migrated]

I am running a dual core headless computer as internet gateway via pppoe with two NICs. eth1 (internet interface) no ip, no dhcp eth0 (LAN interface) - 192.168.0.100 static ppp0 - dynamic ip ...
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0answers
19 views

Asterisk Firewall access Rules

I have a questions regarding the firewall rules for Asterisk VoIP server. I have a restricted access to UDP/TCP port 5060, which seems to be blocking calls. I want to make sure that my VoIP Server ...
1
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2answers
14 views

Use iptables to log connections except for two addresses

We would like to use iptables to log all network connections except if the connecting address is A.B.C.D or the connecting address is E.F.G.H. These two addresses cannot be combined into a single CIDR ...
0
votes
1answer
33 views

Load balancing iptables

I am trying to use iptable for load balancing. I'm working with virtualbox. All vm (debian)are in internal networking and IPs are static. I want to route requests coming to my web server(apache2) with ...
2
votes
2answers
232 views

No SNMP query responses from Ubuntu 14.04 LTS server client machine

Alright, I've got two VMs both running under ESXi. One VM is hosting Observium, which uses SNMP to grab its info. I pointed Observium at my ESXi host directly, and it worked fine, so there's no issue ...
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0answers
16 views

amazon ec2 instance going to a remote ip using openswan tunnel is up but no traffic being established on the remote ip

I having establishing a vpn tunnel to a remote peer/public ip using amazon ec2 openswan. The tunnel is up but no traffic has been seen on our side or the remote side? Is there I been missing? Please ...
1
vote
1answer
76 views

Limit Number of TCP connections in Linux Server, to avoid attack

I want to limit the number of TCP connections in Linux server, I have used the following command. iptables -A INPUT -p tcp --syn --dport 80 -m connlimit --connlimit-above 25 --connlimit-mask 32 ...
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votes
0answers
35 views

Large number of requests, high outgoing traffic [duplicate]

I have a VPS on Linode with Ubuntu 12.04 LTS on which I run my staging server (protected with basic HTTP authentication). I the recent days, I received a high number of requests from a handful of IPs ...
3
votes
1answer
47 views

IPTABLES for multiple Public IP Addresses

Currently i have two servers Running Debian 7 with HA Active/Passive setup using Pacemaker and Corosync as follows: node1->IP->xx.xx.xx.1 node2->IP->xx.xx.xx.2 VIP(Floating IP) ...
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votes
2answers
33 views

Restricting internet access of some client systems of LAN to a few websites using gateway

How to limit internet access of most systems in my LAN to a few websites and block all the other websites? Also want to bypass that restrictions for some systems. All systems have static IP address ...
0
votes
1answer
36 views

Port 53 in Amazon Security Group

Everything works as expected. This question is for learning purposes only. Using Amazon Security Groups in a VPC. Outbound rules are: 0.0.0.0/0 Port 80 0.0.0.0/0 Port 443 Iptables allows OUTPUT ...
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2answers
35 views

iptables -D POSTROUTING -t nat -o tun0 -j MASQUERADE

I was wondering if somone could explain what the purpose of MASQUERADE is. This rule is added and deleted as my openvpn connection goes up/down. iptables -A POSTROUTING -t nat -o tun0 -j MASQUERADE ...
1
vote
1answer
25 views

Two openvpn servers on the same machine, route traffic between the two subnets

I have two openvpn servers ( one on tcp, one on udp) running on the same machine - an OPENVZ vps. The first network A uses 10.10.0.0/24 and it is designed as an intranet. The second network B uses ...
0
votes
1answer
39 views

UFW deny all incoming except SSH

I am about to configure firewall with UFW. I am logged in over SSH so I don't know if the terminal will be locked out as soon as I do: sudo ufw default deny incoming If so, how can I deny all ...
0
votes
1answer
39 views

How to block HTTP floods using IP tables and perm block the attacking IP?

I want to find out how to block HTTP floods fully. I was using this code right here: iptables -A INPUT -i eth0 -p tcp --dport 80 -m state --state NEW -m recent --set --name HTTP iptables -A INPUT -i ...
5
votes
1answer
84 views

Load balancing network traffic using iptables

I am trying to load balance traffic from internal LAN on a linux router having two gateways. Initially I went for the iproute implementation which didnt balance the load as expected, reason being that ...
1
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0answers
42 views

iptables IP address (source and destination IP address) mangling [migrated]

I tried to understand the concept of iptables mangling part, but somehow failed to understand the IP header manipulative section. For example: Below is the system scenario which I'm trying to ...
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votes
1answer
44 views

Iptables doesn't open port 53

I have been trying different ways of opening the port but for some reason doesn't work. The last set of lines that I have used is as follows: iptables -I OUTPUT -p udp --dport 53 -m state --state ...
0
votes
1answer
56 views

Port 80 doesn't work

I have a website in my ubuntu server 14.04, with apache2 server, and untils fews days go the site works fine but, today if I digit www.mydomain.com from my internal network it works but, if I try with ...
0
votes
0answers
14 views

Dropped TCP Packets over two-stage IKEv2 VPNs

Something of a weird setup this: There are two Virtual Private Clouds (10.100.240.0/20 = prod1 and 10.101.0.0/24 = control), which have a valid router between them. Control hosts a VPN that is meant ...
0
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2answers
55 views

ports 993 and 995 not open even though opened in iptables

Hi I have a problem with imaps and pops access of email clients to mail server (postfix/dovecot) telnet from the servers shell (ubuntu 12.04, postfix, dovecot, spamassassin, amavis) to ports 587, 25, ...
1
vote
1answer
39 views

Transparently forward local port to remote server

I have StatsD daemon running on a remote server (x.x.x.x) at 8125. I would like to forward 127.0.0.1:8125 to x.x.x.x:8125. I have already tried running the following on localhost echo 1 > ...
0
votes
0answers
24 views

Nodejs remote debugging ports closed

I have a problem with nodejs remote debugging. I'm using centos on remote server and phpstorm on my PC. When I open putty: I type in command: node --debug-brk=5858 main_server.js, and the output is: ...
0
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0answers
15 views

DD-WRT route between vlan2:1 and vlan2 [migrated]

I've been trying to configure a Netgear R7000 with DD-WRT on board. My problem is the fact I have a private ip assigned to the WAN (vlan2) and a public ip assigned to vlan2:1 If I use only iptables ...
0
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2answers
32 views

Load balancing IPTABLES POSTROUTING rules

I have an interface with 5 IP addresses assigned to it (as virtual adapters) let's call them x1,x2,x3,x4 and x5. Currently I have SNAT POSTROUTING forwarding rules from local source range to specific ...
0
votes
1answer
54 views

Access two web servers (VPS and Windows Server) through the same IP (PUBLIC AND VPN) using VPN [closed]

I have two servers: a hosted VPS with a website on port 80, and a home server running windows 7. See the diagram below. The home server is running WAMP on port 88, which works on my home's public ...
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votes
0answers
18 views

iptables NATed traffic is not getting ack back

Ok, I'm trying to setup the classic iptables DNAT/SNAT scenario (RHEL 6.5, 2.6.32-431.17.1.el6.ppc64 kernel ): *Host A 172.16.0.0/24 nets Host B 172.16.0.0/24 + 192.168.0.0/24 nets Host C ...
1
vote
1answer
27 views

Redirect packet that matches a pattern?

How can I route an incoming udp packet with iptables that matches a pattern like: 53 41 4D 50 5B 79 95 DB 61 1E 69 from public interface (vmbr0) and port 7777 to 192.168.0.1:7777?
0
votes
1answer
21 views

Why port 22 redirection causes lxc containers to ssh to host?

I have a host A on which I have 2 lxc container (X and Y). I originally had port 22 on my host (A) forwarded to X. Using this configuration, I wasn't able to ssh out of the container X and when ...
1
vote
3answers
86 views

Forward Traffic in & out, NAT iptables

I have a box setup as DHCP Server with NAT ipv4 forwarding enabled. Currently the box uses eth0 to connect to a local network and has access to the internet, it has another 3 interfaces, eth1, eth2 ...
0
votes
2answers
44 views

Port forward with iptables

I got lo (127.0.0.1) and eth0 (172.17.0.8). I want to redirect packets that land on 127.0.0.1:80 to 172.17.42.1:80 (route from eth0). I tried iptables -t nat -A OUTPUT -p tcp --dport 80 -d 127.0.0.1 ...