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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25 views

linux iptables walled garden [on hold]

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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2answers
69 views
+50

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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0answers
14 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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2answers
827 views

Limiting interface bandwidth with tc under Linux

I have a linux router which has a 10GBe interface on the outside and bonded Gigabit ethernet interfaces on the inside. We have currently budget for 2GBit/s. If we exceed that rate by more than 5% ...
1
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0answers
41 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 ...
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0answers
44 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 ...
2
votes
1answer
22 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 ...
0
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1answer
730 views

iptables rule(s) to send openvpn traffic from clients over an sshuttle tunnel?

I have an Ubuntu 12.04 box with OpenVPN. The VPN is working as expected -- clients can connect, browse the Web, etc. The OpenVPN server IP is 10.8.0.1 on tun0. On that same box, I can use sshuttle ...
0
votes
1answer
624 views

block access to wrt from vlan using iptables dd-wrt

I set up multiple isolated vlans in dd-wrt. Now I need to forward a port to vlan2. I isolated the vlans using: iptables -I FORWARD -i br0 -o vlan2 -j DROP iptables -I FORWARD -i br0 -o vlan3 -j DROP ...
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votes
2answers
35 views

How to manage PING replies? [on hold]

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 ...
4
votes
3answers
1k views

pptpd not working externally on Ubuntu Server 11.10

I am trying to set up a pptpd vpn on our newly installed Ubuntu 11.10 64 bit server, but am not having success having a client connect via an iPhone to the VPN. Note that no clients have been able to ...
1
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1answer
29 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 ...
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 ...
0
votes
1answer
703 views

ZenOSS webinterface connecting problem

I'm having a problem with ZenOss. I installed the centos stack installer on Centos 5.5 x64. De installation succeeded and no errors where displayed. But when I tried to surft to the ip address it ...
3
votes
3answers
2k views

Advanced routing problem

I have 2 internet links using 2 ADSL routers and I need to give access to the Internet for the 192.168.0.0/24 network. I have to route outgoing traffic based on port number, protocol, … using ...
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0answers
36 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 ...
-1
votes
1answer
38 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 ...
1
vote
1answer
905 views

how to limit upload bandwidth per user in linux?

Can anyone provide the tc command to limit upload bandwidth per user in Debian Lenny? I found that to mark packets per user with iptables I can use the following command iptables -t mangle -A OUTPUT ...
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0answers
24 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 ...
2
votes
2answers
782 views

Iptables: Forwarding packets doesn't work

I have 3 Linux Systems A, B and C. A is a TCP Client and sends a message to TCP Server on C. A can see only the external IP of B which is at wlan0 interface, 192.168.0.3 ------------------ ...
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votes
2answers
51 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 ...
3
votes
1answer
173 views

Packets not entering FORWARD chain

first of all, this is not an every-day routing issue. The setup is fairly complex, so let me state it before. I got a router with, lets keep it simple, 3 interfaces. eth0, eth1, eth2. eth2 is used ...
2
votes
3answers
1k views

Iptables massive 1:1 NAT

I have to connect two LANs: LAN1: 10.10.0.0/16 and LAN2: 192.168.0.0/16. I can't do simple routing, because 192.168.0.0/16 net is prohibited in LAN1, so I am thinking of using Full cone nat (1:1) to ...
1
vote
1answer
38 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 ...
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votes
3answers
764 views

OpenVPN client connects but can't access internet

I setup an Openvpn server on a centos box and I can get the client to connect (osx) but can't access the internet or even the local network. I thought maybe DNS but couldn't access any sites via IP. ...
1
vote
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
17 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 ...
0
votes
1answer
28 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 ...
0
votes
2answers
31 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 ...
0
votes
1answer
472 views

mod_evasive DOSSystemCommand not working

I'm trying to get mod_evasive to fire off a script to add an iptables rule to deny the offending host. I've tried the suggestions from both answers here but I still can't get it working. Apart from ...
0
votes
2answers
41 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 ...
7
votes
2answers
1k views

iptables -L pretty slow. Is this normal?

Quick question but Gooling has not revealed an answer. When I do iptables -L, it seems to lag on displaying items in where I have limited the source to internal ips 192.168.0.0/24 The whole listing ...
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2answers
15 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 ...
4
votes
2answers
157 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 ...
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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 ...
0
votes
1answer
633 views

iptables: No chain/target/match by that name.

I am using this command to attempt to block this vulnerability scanner based on it's string, which is returning an error. # iptables -I INPUT -j DROP -d xxx.xxx.xxx.xxx -p tcp --dport 80 -m string ...
0
votes
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
votes
1answer
27 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 ...
0
votes
2answers
661 views

iptables+iptables_netflow: iptables blocking netflow export?

I am running an iptables firewall on OpenSuSE 11.3 --recently I became interested in traffic monitoring and accounting, and to this end installed iptables_netflow module on the firewall and WANGuard ...
0
votes
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
0answers
17 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 ...
0
votes
1answer
32 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
29 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 -> ...
0
votes
1answer
30 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 ...
1
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0answers
31 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
3answers
67 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 ...
0
votes
1answer
1k views

SSH Socks Proxy wiith iptables REDIRECT

I have googled and haven`t found the answer on my question. Help me please. There are two servers: serverA with public IP 12.0.0.10 and an private IP 10.0.0.5 serverB with public IP 20.0.0.11 I ...
5
votes
4answers
713 views

Openvpn, forward packets very slowly

I rebooted my server, and an odd issue just came out. I am running on ArchLinux, the clients are Ubuntu, Android and Mac. The problem is that accessing the internet via the clients is slow, about ...
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0answers
25 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 ...