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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OpenVPN advanced privileged client access customization

I have implemented an OpenVPN server running on Tomato router (Let's call the router TR) the OpenVPN server is using TUN interface which means connections between clients and servers are based on ...
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0answers
13 views

iptables failed to forward packages to NFQ

I have set the following rules in iptables: sudo iptables -I INPUT -i eth0 -p tcp -s 192.168.37.184 -j NFQUEUE sudo iptables -I OUTPUT -p tcp --dport 3306 -j NFQUEUE What I want to do is forward ...
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1answer
34 views

iptables configuration failed

My iptables just suddenly became unable to be edited. It still runs fine but I am unable to do anything to the configuration such as opening or closing ports. I keep getting this error: ...
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0answers
12 views

ospf hello not forwarded

I am trying to change the destination ip of ospf hello packet (224.0.0.5) to link local address using iptables rule (DNAT) . It does not seem to work. A similar rule for unicast packet (BGP control) ...
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0answers
15 views

How accessing a NATed, virtualized (LXC) server over public IP from client itself on a bridged network?

Setup ____________________________ ____________________________ | Host | | Client | | Public IP: 66.66.66.66 | ...
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0answers
34 views

iptables block outgoing from specified IP [on hold]

I have a VPS with 4 IPs, they are on eth0, eth0:0, eth0:1 and eth0:2, how would i block eth0:0 to eth0:2 traffic to a specific port and only allow eth0's traffic to that port? I already tried ...
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0answers
19 views

iptables will only allow access to my website from external net [duplicate]

I am having an issue with my new Debian Router / Firewall. I have a Ubuntu server hosting a website on my internal LAN. If i try to connect from outside my LAN, eg. my phone, I have no issues. But if ...
1
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0answers
22 views

Openstack instances, routing, packets not delivered for SPECIFIC services

I am taking over management of an existing openstack system at work and I have only a little prior experience with openstack. I have about 8 instances running and all of them appear to function ...
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0answers
29 views

linux iptables walled garden [closed]

Can I create a walled garden using IPTABLES (and without using proxy like squid) on debian/raspbian system which would control access to certain pages ( allow facebook,gmail and my local httpserver, ...
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0answers
20 views

Firewall and NAT settings in GSM modem for one server

I have a GSM Modem (PSI-MODEM-GSM/ETH) in field with one device behind, acting as a server. The situation is as follows: "PC" | \_________Dynamic IP: 10.103.153.122 | ...
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1answer
25 views

iptables: does a scanner knows if you DROP packets?

I know how REJECT and DROP chain works. But, as I read here REJECT vs DROP when using iptables, user Dagelf said that the server still replies with TCP SYN/ACK. Does the scanner knows that a packet ...
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0answers
49 views

IPTABLES: why does accepting outgoing DNS on port 53 bring down my websites?

I have a handful of websites running with Apache. I've installed Sendmail and am trying to configure IPTABLES to allow outbound emails. When I allow output DNS with the following command, I can send ...
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votes
2answers
35 views

How to manage PING replies? [closed]

How can I manage, for example, my Ubuntu mashine so it doesn't (or does) respond to PING(ICMP ECHO_REQUEST - type 8) requests? Normally almost all computers in a LAN network responds to ping with an ...
0
votes
1answer
13 views

iptables port forwarding rule ignored

I want to forward the traffic from port 1111 to port 2222. So I execute the iptables command, but it seems that, somehow, the rule is not being saved. # iptables -t nat -A PREROUTING -p tcp --dport ...
1
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1answer
31 views

Port based routing on ubuntu

My situation: A ubuntu server is part of a LAN with 2 gateways. The one offers high speed with high latency. The other low speed with low latency. My server usually uses GW1 for all traffic (because ...
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0answers
46 views

Routing LDAP traffic from Application server to Proxy to internet

I've included a drawing so you get an idea how it would work. (Red = LDAP connections , Blue = HTTP / AJP in the backend) Problem: We want to connect our customer application server to an LDAP of ...
-1
votes
1answer
39 views

iptables NAT table not matching anything [duplicate]

I am attempting to take a TCP service running on port 1234, and make it appear as if it's running on port 81. I thought the following might do it: iptables -A PREROUTING -t nat -p tcp --dport 81 -j ...
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0answers
27 views

Is there a way to alter payload data in iptables

I want to alter the data in payload. Lets take a case, the packet is DNS request packet and I want to alter the domain name in the payload. Is there a way to accomplish this without going to ...
0
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0answers
37 views

debian multiple network interface multiple networks

I have a virtual environment with 3 virtual machines on one host. One of my virtual machines has 2 network interface. I need the virtual machine with two interfaces to connect to two different ...
0
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2answers
54 views

IpTables Configuration Not Working to block ports (Centos 6.2)

I am trying to only allow certain IPs to access port 8209. I have tried a few different methods that I read on ServerFault. This method is the most recent one I have tried. I manually edited my ...
1
vote
1answer
51 views

Port 80 redirects to CPanel's /cgi-sys/defaultwebpage.cgi even after forwarding

I recently took over the management of a website using a pure Tomcat 6 server (i.e. no combination Tomcat+Apache) with CPanel installed, which is only accessible on port 8088 (i.e. the main page URL ...
1
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1answer
20 views

Accessing a container from another container using the public IP of the host

I've some issues configuring properly the network in proxmox. In short, from a container, I can reach any web server outside (ex: google.com), but I can't reach the web server on my container. The ...
0
votes
0answers
23 views

How to configure nDPI for iptables

I am new to nDPI, I have installed nDPI but when I add rules like; iptables -I OUTPUT -m ndpi --http -j REJECT it shows error iptables v1.4.7: Couldn't load match ...
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0answers
19 views

Accessing Windows VMs on Linux hosts remotely

At one of my work sites, we have a set of Linux servers, one of which acts as the main router. On another Linux server inside the network, I'm running Server 2012 in a VM. The Remote Desktop of the VM ...
0
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2answers
38 views

How to block requests for virtual hosts that dont exist in apache [duplicate]

First up, check out this question: Why are external domains appearing in my apache logs? We're seeing the exact same thing on one of our Debian VPS servers - with one big difference, the regularity ...
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2answers
42 views

Why does these iptables rules does not work

I think a bit more detail is needed. I have opened a new cafe in my area and people are downloading stuff that are increasing my bills, so I want to block protocols on my router and then re enable it ...
0
votes
1answer
37 views

Forward all network packets from server A to server B (WAN) Ubuntu

I currently run a game server on a VPS and will shortly be moving VPS provider. To make the migration easier on the players I would like players to be able to use the original IP for a short while by ...
1
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2answers
136 views

CentOS6 Iptables deletes rule after 24 hour

Since I updated my CentOS server with yum update and now some of my iptable rules get deleted after a while. When I notice the server closed down my port I can simply fix this by: service iptables ...
1
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2answers
19 views

Sendmail Domain of sender address does not resolve. Unable to send any emails.

I've got myself in a muddle with Sendmail. I've newly inherited responsibility for an app that uses sendmail and I have no previous experience. I'm using Ubuntu Ubuntu 10.04.4 LTS. Recently we ...
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votes
2answers
46 views

Iptables save expected behaviour [closed]

I was updating my iptables in CentOS 6.4 I added port 8080 to iptables and ran iptables save. However now when I view my iptables all it is showing me is: # Generated by iptables-save v1.4.7 on Wed ...
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0answers
15 views

iptables segfault messages in syslog [duplicate]

I have an Ubuntu 10.04 64 Bit server that has suddenly started to report a lot of segfaults error in the syslog. The full message in the log is : kernel: .IptabLes[14283:932171]: segfault at 0 ip ...
0
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1answer
30 views

SSH attacks, how do their usernames end up in auth.log? (pw auth disabled)

So this computer is reachable on port 22 (from everywhere). Since messages indicating failed login attempts (usernames like root, cgi, bash, production...) have been flooding /var/log/auth.log, I have ...
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1answer
50 views

Attack from strange IP address, how to block?

Looking through the mail logs I've noticed a lot of these: Apr 7 11:33:25 s123456 pop3d: IMAP connect from @ [::ffff:192.96.206.9]checkmailpasswd: FAILED: web14p3 - short names not allowed from @ ...
0
votes
1answer
38 views

Force OpenVPN Access Server clients through proxy?

I have an OpenVPN Access Server (v2.0.3) which I use to provide remote access to a dozen or so users, as well as a small site-to-site connection with a pfSense gateway. I am currently pushing a proxy ...
0
votes
1answer
31 views

iptables NAT forward range

I have two network interfaces, eth0 and eth1. eth0 has a public ip, eth1 has 172.16.0.254/24. I'd like to do the following mapping: 172.16.0.1:22 -> eth0's public ip:2001 172.16.0.2:22 -> ...
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0answers
32 views

Confirm IPTables firewall settings for NFS v4 server?

This question has been asked here before but has conflicting and possibly outdated answers. It seems to depend on OS, version of OS, and version of NFS. On a CentOS 6.5 server, the default rules are ...
0
votes
1answer
19 views

Squid + Apache error

I had my Apache webserver perfectly configured and everything worked fine. I asked my friend to setup a cache proxy to make my web answers faster. So here's what he did (if I understand the history): ...
0
votes
1answer
31 views

Iptables/ufw - blocking ports when using nat

I use NAT to move requests from external ports to an internal ip address and port hosted with proxmox. Something like this: iptables -t nat -A PREROUTING -i vmbr0 -p tcp --dport 8000 -j DNAT --to ...
0
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3answers
73 views

Capture first packet of established TCP connection with iptables?

I'm looking for a way to examine the first packet only of a newly established TCP connection (the first packet with actual payload, that is). Is there a way to do this with iptables? Matching ...
1
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0answers
28 views

Something (but not iptables) mysteriously redirects network traffic - how to diagnose?

Summary There is a virtualbox host (1.1.1.5) and a routed guest (1.1.1.6). Something redirects any traffic on port 25 with the guest, whether ingoing or outgoing, to 1.1.1.5 port 2525 and I cannot ...
4
votes
2answers
163 views

packets sent on virtual IP don't hit iptables rule

I have a virtual interface eth1:3 with IP address 222.192.124.3, I have set up an iptables rule to log packets coming on that interface using the interface's IP (I know iptables doesn't care about ...
0
votes
2answers
82 views

How to do the port forwarding from one ip to another ip in same network?

I would like do some NAT in iptables. So that, all the packets coming to 192.168.12.87 and port 80 will be forwarded to 192.168.12.77 port 80. How to do this with iptables? Or Any other ways to ...
0
votes
1answer
26 views

iptables stopping access to websites

I have iptables set up on a server to only allow whitelisted ips to access it: :INPUT ACCEPT [1695:323274] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [987:756890] :xxx - [0:0] -A INPUT -s 12.34.56.78/32 ...
1
vote
1answer
39 views

Having difficulty connecting to port

I'm giving Linode a try, and I just launched my first instance running CentOS. I've been unable to connect to a port on the box even if I completely drop the firewall. (My script does successfully ...
0
votes
0answers
19 views

fail2ban bans without running? [closed]

I do have a problem with my webserver. Its an Ubuntu 12.04 LTS, with: Apache: Server version: Apache/2.2.22 (Ubuntu) Server built: Mar 19 2014 21:11:10 MySQL: mysql Ver 14.14 Distrib 5.5.35, for ...
2
votes
1answer
38 views

iptables blocking local connection to mongodb

I have a VM (Ubuntu 12.04.4 LTS) with mongodb (2.0.4) that I want to restrict with iptables to only accepting SSH (in/out) and nothing else. This is how my setup script looks like to setup the rules: ...
0
votes
1answer
59 views

Network remapping with iptables and PPTP VPN

I have two different networks: Home network 192.168.1.0/24 A - Home PC (192.168.1.100) B - Home Router (192.168.1.1 lan ip - x.x.x.x public ip) Office network 192.168.1.0/24 C - File Server ...
0
votes
1answer
49 views

How to redirect a website using IPtables?

I have referred to the following links before asking this question. I am making an example for my students on NAT - pre-routing. Here, I am trying to replace the destination ip with the one I want. ...
0
votes
1answer
27 views

software based captive portal for wide area [closed]

I'm trying to organise some wide wifi network imagine a small town with several wifi points when user is connected to a wifi point, device is redirected to captive-portal(cp) website where they must ...
0
votes
0answers
16 views

customised client to client connection configuration inside OpenVPN server

I have two clients with common names [client_sina] and [client_extra] that are connecting to an OpenVPN server on remote place via (TUN21) running on Tomato Router The only physical port of the ...