iptables allow creation of rules to define packet filtering behavior.

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1answer
49 views

iptables drop length and TTL condition doesn't work

With iptables utility on Linux host need to create mini firewall. I need to drop all incoming connections with package length greater than 722 AND TTL greater than 22. Need exactly AND. Drop only if ...
2
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1answer
512 views

Bad built-in chain name with iptables-restore

I saved my iptable settings on a Ubuntu 11.4 system using iptables-save >filename I then replaced the Ubuntu system with CentOS 6.5 and tried to restore iptables using iptables-restore ...
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0answers
558 views

Corosync & Pacemaker IPTables Rules

When using Corosync with two rings via multi-cast addresses 226.94.1.1 (Port 5405) & 226.94.1.2 (Port 5406) what iptables rules are required to allow two nodes to communicate optimally without ...
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0answers
239 views

IPtables rule to double NAT [closed]

Let me rephrase it.. I just need an IPtable rule to do double NAT-ting.. Host A - Host B - Host C - Host D Host B should do both source NAT and destination NAT, so that my request from Host A ...
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0answers
475 views

Route all HTTP traffic through polipo

I've set up polipo on my machine to listen to the default port 8123. To test it, I set the in-memory cache to a ridiculously high 2 GB and downloaded a 50 MB file using wget utilizing the proxy. ...
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273 views

iptables REDIRECT in combination with matching on interface vs. IP address

I've successfully set up Tor for transparent proxying using iptables (ie, all outgoing traffic is sent through Tor without the application's knowledge). In doing so, I discovered both an odd problem ...
2
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0answers
279 views

SNAT problem in iptables

I am trying to reroute traffic from specific devices in my house over openvpn. For this, I've created an OpenVPN tunnel between my house wifi router and my server. Here is my setup: Wifi router's ...
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216 views

IPTables dropping UDP packet stream

I have a configuration where UDP packets containing encapsulated DNS data are sent to a KVM instance for processing. The KVM instance sits behind an IPtables firewall which is also doing NAT. The ...
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331 views

Iptables and Port Scanning and Recent module

I'm trying to write an adaptive firewall using iptables, and am not clear on how the recent module is working. For example, see http://blog.zioup.org/2008/iptables_recent/ Snippet from my iptables: ...
2
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1answer
194 views

LAMP Hardening, Transparent Proxy with iptables

I'm running a LAMP server with FTP(S) and several users. The users have only access to uploading PHP files and other web content. Some are running Drupal and Wordpress, but also a few home made stuff. ...
2
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368 views

TPROXY for redirecting UDP on arbitrary ports

I want to intercept all UDP traffic leaving tap1. And possibly reply to e.g. DNS-requests. To accomplish this I wrote some python code listening to localhost and use iptables with a rule-set like ...
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0answers
271 views

Port Forwarding Between 2 Internet Machines

Here's my scenario: Setup There are 3 machines: A: on the internet : has ip (a.a.a.a), has port pa open B: my server / gateway : has ip (b.b.b.b), has port pb open C: on the internet : has ip ...
2
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1answer
357 views

iptables doesn't forward from WAN to virtual machines

I have a machine working like gateway and have two network interfaces: eth0 LAN : 192.168.1.0/24 eth1 WAN : XXX.XXX.XXX.XXX (my public ip) This machine has 3 VM guest over virtualbox. All have ...
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2answers
604 views

Having trouble with packets not making it into Fedora 16 Apache [closed]

Background: I haven't done anything with iptables in a few years... I have Fedora 16 running in a VM on VMWare, with my firewall (TomatoUSB) port forwarding to the VM. VM is at 192.168.1.155. I know ...
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0answers
579 views

Iptables - modprobe: FATAL - Fail2ban random restarts

I have been running fail2ban on my server for a while without any problems but have recently seen fail2ban restart randomly. After some looking in my logs I noticed that the restarts occur when ever ...
2
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1answer
697 views

Will the Firewall GUI in CentOS overwrite changes implemented by IPTABLES manual edits?

I would like to restrict access to the SSH port of a new CentOS 6.2 server to select IP addresses but the Firewall GUI utility seems to be an all-or-nothing scenario. Either the port is firewalled or ...
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0answers
445 views

Why are packets not moving forward? [closed]

I have a server with forwarding turned on. I placed an iptables LOG target in the PREROUTING, INPUT, and FORWARD chains of the mangle table. I can see the LOG messages from PREROUTING, but not INPUT ...
2
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1answer
302 views

pptpd dead but subsys locked? on cent os

i install point to point tunnel (PPTP) in my VPS. (Cent OS 6 64 Bit) everything fine after reboot the PPTP not worked client side. the pptpd status shows " pptpd dead but subsys locked ". how to ...
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3answers
2k views

Iptables GEOIP not working under Debian Squeeze

I've just installed xtables-*, compiled the geoip database, but when I try to use an iptables command it always gives back the following error: Command: iptables -I INPUT -p tcp --dport 80 -m geoip ...
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3answers
2k views

hosts.allow: Not required when using iptables?

I am trying to configure the box I am using as a gateway/proxy/firewall to allow IP masquerading and finally switch over from using a proxy. It's a debian squeeze system. Currently, my hosts.allow ...
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1answer
917 views

Control bandwidth with iptables

How can I control bandwidth in RHEL 5 using iptables?
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2answers
494 views

Saving an iptables configuration permanently

How can I save this configuration permanently? sudo iptables -t nat -A POSTROUTING -s 10.10.0.0/16 -o eth0 -j MASQUERADE
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1answer
115 views

Undoing specific iptables ip/port restriction

Say I add the following iptables rules: iptables -A INPUT -p tcp -s localhost --dport 4444 -j ACCEPT iptables -A INPUT -p tcp --dport 4444 -j DROP This allows localhost to access port 4444 then ...
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1answer
156 views

IPv6 firewall rules seem to impede all connections

After deciding that my small server needed a firewall, I used ferm to configure iptables and ip6tables for me (this question should be tagged ferm, but I cannot create the tag). I am using the same ...
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2answers
240 views

How is the loopback device traffic allowed?

How can I allow the traffic to be sent on the loopback device (lo)? What is the iptables command for it?
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2answers
286 views

iptables and logs

Suppose I add an IP to iptables blocking for exim, dovecot and FTP and this IP visits my server again. Is there any log of this visit so I can confirm the IP was trying to reach the server again but ...
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1answer
6k views

How to modify iptables rules via editing a file rather than interacting via command line?

In the history, i would simply edit a file and then reboot the whole server. i would clone the line that had port 22 open change it to 80 and then save the file.. and reboot the whole system so ...
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2answers
97 views

Reject ssh connections made from proxies

I was seeing this question which was concerned with blocking access to the users who do not belong to a particular region. I am sure that blocking is possible but I see there is a workaround to this. ...
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1answer
178 views

How to log incoming icmp traffic?

I am watching my ip6table and observing an icmp packet arriving and getting dropped at the rate of 1 per second. I am trying to find out what that message is about. I tried using tcpdump (it is ...
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1answer
6k views

iptables forward all traffic to interface

I have two interfaces eth1 and eth0. I want all traffic on eth0to be forwarded to eth1. I created an iptable rule like this: iptables -A FORWARD -s 0/0 -i eth0 -p tcp -o eth1 -j ACCEPT But this ...
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1answer
110 views

Is this what it looks like in the terminal on the client side when you are blocked out via fail2ban?

I am a new server admin. I just setup fail2ban on an ubuntu 12.04 VPS. I used this tutorial. Then I tried to login to the system via ssh from a friend's machine. It is showing "operation timed out." ...
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3answers
3k views

How to change user agent on all http requests made from my machine with Squid intercepting proxy?

I'd like to change the user agent on all HTTP requests made from this machine. It's easy enough to change the user agent in each browser, but other apps also make http requests. It's vital I catch ...
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1answer
489 views

How do I shut down ports remotely without shutting myself out?

I have an Ubuntu 11.04 server in a remote location on another continent, so I have no physical access to it. I only interact with it by ssh (and scp), and intend to only ever interact with it that ...
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2answers
236 views

Drop TCP packets and prevent TCP retransmission

I have an application that sends TCP data to a server. My server is made to intentionally drop the packets sent by the application, and as a result the client retransmits the packets. I need to ...
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1answer
48 views

Confused by different output from iptables -L

I keep following this tutorial using a bash shell on ubuntu 12.04 as I open more and more ports on my server. I usually open up ports like this sudo iptables -A INPUT -p tcp --dport PortNumberToOpen ...
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1answer
82 views

View blocked address from sshguard

How can I view all the addresses that sshguard has blocked to iptables?
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2answers
154 views

What network protocols do database servers use?

I have a postgres 9.1 server running on the default port 5432 on an ubuntu 12.04 cloud server. I want to open up the port so I can make remote queries -- but I have to open the port on IP tables, ...
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1answer
152 views

Redirecting all IP over USB traffic to a fixed address

I'ma bit of a network newbie, so apologies for the inaccurate vocabulary. Say I have a device connected by IP over USB to my computer (running Ubuntu), that connects to 10.0.0.1. I configured my ...
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2answers
611 views

iptables: what the difference between filter and mangle

I am using iptables to to mark the package and want to route based on the marks. First I added the ip rule: sudo ip rule add fwmark 1 prohibit (The "prohibit" is just for test, I will change it ...
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2answers
1k views

Missing iptables file on directory /etc/init.d/ (Fedora 17)

Is the iptables file in Fedora 17 moved from /etc/init.d/ to /etc/sysconfig/? I need do some patching to the iptables file to solve the firewall problem (Setting chains to policy ACCEPT: security raw ...
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1answer
411 views

What does the route Dest: 123.123.123.123, GW: 0.0.0.0 mean?

I have a route table: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 123.123.123.123 0.0.0.0 255.255.255.255 UH 0 0 0 ...
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1answer
568 views

Allow user to see how many iptables rules are loaded, but not actual contents?

I want to allow user to check how many rules are present in filter table, but not able to view actual rules, is that possible? literally I mean iptables -L | wc -l (I know it's faulty), but sudo ...
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1answer
3k views

Redirect Output with Iptables

Is possible on Debian to change the port of packets that are going to a specific port, using iptables? Example: I want packets going in the outbound direction to a.b.c.d for port 1723 to be ...
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1answer
2k views

Redirect http using iptables for an ip range

I have a range of ip addresses (10.13.13.10-19) that I want to redirect all outgoing http traffic to an internal webserver. So if someone in that range tried to access any site, the html from my ...
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1answer
2k views

Why can't I add any iptables rule?

Why can't I add any iptables rule? root@ROUTER:~# iptables -L INPUT -v Chain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 6934 685K ACCEPT 0 -- any ...
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2answers
970 views

iptables rule for local network with free internet blocking unrequested connection from internet to server?

I have a home server (with slackware 13) with a eth0 for the local network and a eth1 for the internet (cable modem with dynamic ip). While I do want to learn more about iptables I am still on the ...
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2answers
39 views

iptables is ignoring rules?

I've found some strange traffic through tcpdump (traffic is ongoing always): 13:00:13.203754 IP 1.2.3.4.1028 > 188.113.188.16.56881: UDP, length 103 13:00:13.204396 IP 1.2.3.4.1028 > ...
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1answer
30 views

Iptable forward interfaces for gateway machine

I have two Ethernet interface being configured to use as system gateway ex: eth1: 10.10.1.0 eth2: 10.10.2.0 I want to forward all the packets which are coming to the 10.10.2.0 gateway contacting ...
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3answers
28 views

Why did this iptables rule block my webserver?

I was setting up Mathematica on a remote server, and needed access to the UI. I set up VNC according to http://wiki.centos.org/HowTos/VNC-Server , and got it working, which involved making an ...
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1answer
192 views

Configure NAT filtring behavior with iptables

I'm using this rule to configure SNAT: iptables -t nat -A POSTROUTING -o eth1 -j SNAT --to-source 193.49.142.107:4000 I want to specify a rule to filter out packets not destined to the internal ...