Questions tagged [iptables]
An application that allows a user to configure the tables provided by the Linux firewall. iptables is succeeded by nftables as of 2014.
154
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1answer
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Is it recommended to drop all traffic by default in iptables after accepting only what is required?
I was told using iptables -P OUTPUT DROP after rules such as iptables -A OUTPUT -p tcp --dport 80 -m state --state NEW -j ACCEPT to accept what is required didn’t do much from a security standpoint. ...
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What is the most restrictive way to allow IPv6 ICMP requests on iptables?
This is what I have so far but it is pretty open.
*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT DROP [0:0]
-A INPUT -p ipv6-icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A OUTPUT -p ipv6-icmp -j ...
0
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0answers
34 views
Can iptables or route be used to eg double-DNAT so traffic appears to be from a different bridge?
I have a host with different bridges and a daemon not only to listening on a certain IP, but it is also attached to the bridge. I would like to communicate with this daemon with traffic coming from ...
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1answer
50 views
How do you securely give access to a Java App interactive console (Linux/GNU)?
I have a Java App running, which prints out messages into STDOUT and also has an active interactive console (also accepts STDIN), when the server has started up.
How do I securely give access to an ...
0
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1answer
60 views
iptables: force clients to use proxy
My network: 192.168.0.1 server. (enp0s3 NAT, enp0s8 internal) 192.168.0.10-15 clients (enp0s3 internal).
I have a proxysquid for blocking websites,and so on.
My clients can navigate and browse any ...
1
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2answers
773 views
Block SYN,ACK response with iptables
I have a virtual environment and I am making a SYN flood attack to a Ubuntu Server's port 53 using Kali 2020.
I realized that a countermeasure for this attack is to limit or block the responses to ...
3
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0answers
46 views
smb iptables configuration not working with vpn killswitch
my main goal is to setup iptables that work as a VPN killswitch for my openvpn connection. Thanks to a post from forest, this was pretty straight forward: OpenVPN kill switch on Linux . So. everything ...
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1answer
94 views
Does this iptables entry indicate someone's trying to break in?
Two days ago I built a Debian 10 server in the United States for use as a file server for my web application. When I created the server, I installed the fail2ban package and configured a basic, ...
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1answer
116 views
Local Burp Proxy not showing routed packets
I created a hotspot on wlp2s0 and connected an android device, whose IP is 10.42.0.62.
I am trying to route my all packets from my wlp2s0 interface to burp proxy which running on 8080 and I also ...
2
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0answers
553 views
TCP reset attack / forged TCP reset prevention
How do you prevent someone from doing an TCP reset attack between client and host without having acess to host?
I am trying to solve a CTF for fun and learning purposes.
In one of the challenges I ...
11
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1answer
3k views
Has a remote rogue DNS client managed to slip through the first iptables rule of a Linux DNS server?
Ubuntu 20.04
iptables 1.8.4-1
I experienced a situation where a remote system seemed to be able to slip through the first iptables rule of a Linux server located behind a NAT router:
-A INPUT -s <...
0
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1answer
189 views
MITM setup using airmon-ng, iptables, and isc-dhcp server
I want to set up a MITM-scenario as an exercise for myself. My setup looks like this:
Internet <--------> Laptop <----------> Client
At this stage I just want to route the traffic from my AP ...
1
vote
1answer
79 views
Why am I receiving hits with SPT=443 on IPv6?
I block most everything with my firewall, what I don't get is why would I constantly receive hits to connect on random ports from port 443.
[iptables] reject_ipv6: IN=eno1 OUT= MAC=...
SRC=2607:...
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1answer
149 views
How to block all inbound traffic from a specific Internet address or subnet using TomatoUSB router software (LINUX based)
I'm not trained in Linux, but I think I found the solution to my problem documented, but it is not working as expected. I am NOT an iptables guru, I'm learning as I go.
A Russian IP is trying to ...
0
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1answer
64 views
Even though my firewall is active, is it protecting me fully given that the 'rules' are not active?
Even though my firewall is active, is it protecting me fully given that the 'rules' are not active?
Output shows:
host based firewall active, empty rules
iptables modules loaded, but no rules ...
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2answers
546 views
How does TLS traffic impact firewalls?
If I have an open port on a firewall it means that I can receive traffic on that port. If it's unencrypted I assume that the raw data is just allowed through.
If TLS is being used, does firewall ...
2
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2answers
154 views
How are my iptables rules circumvented?
I'm using ufw on a debian server and apparently an attacker is able to circumvent the filtering rules. ufw uses iptables.
The server host http and mail services, and has an ssh port. I use a non-...
2
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2answers
3k views
Why can't iptables drop arp requests
I was trying to hide my laptop from my phone's network scan app. The app is using arp requests to find devices on the network. I tried everything on iptables. It doesn't work, even if i set all the ...
3
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0answers
177 views
Experimenting with SSLStrip+ on the same machine
I am trying to play around to understand how SSLStrip+ works by:
$ cat /proc/sys/net/ipv4/ip_forward
1
$ sudo iptables --flush
$ sudo iptables --flush -t nat
$ sudo iptables -t nat -A PREROUTING -p ...
0
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1answer
665 views
watch DNS queries while using OpenVPN.-
I want to monitor/sniff the DNS queries I make while I'm using a VPN connection with my OpenVPN client.
My initial motivation was to check if I'm leaking DNS queries; then using this page it seems I'm ...
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0answers
43 views
Are parts of my system susceptible to IP based malicious attack even with effective IPtables rules?
Yesterday I installed Cent OS 6 and had to flush the default IPtables rules (IPtables -F) in order to access a web app via my browser.
Having very little experience with Linux/Network security this ...
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2answers
1k views
Dealing with the dangers of self-hosting a webserver?
Assuming for a self-hosted webserver:
the webserver only hosts a static html website
iptables is used to reject every IP except a few known ones
only Port 443 is forwarded and the website requires ...
1
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1answer
601 views
Building a malicious captive portal
So I'm trying to build a malicious captive portal but I'm stuck on the part where you need to know stuff.
Anytime a HTTP request comes in, everything works fine. However, when an HTTPS connection ...
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1answer
165 views
Is iptables and vpn tunneling enough? [closed]
What is the best approach to secure connection between two devices over the internet (public IP)?
if there is a firewall on my public IP address deny access all incoming connection, can the hacker ...
2
votes
1answer
49 views
What are the methods by which an attacker can distinguish between DROP on IPtables and a Nullroute or non-allocated IP?
Let's say we have a server set up with set to:
iptables -P INPUT DROP
Without any other rules on the input chain.
Ignoring accessibility issues outside of physical server access, what are the ...
10
votes
1answer
10k views
Connection to ports 2000 and 5060 successful despite filtering
I run my own (Ubuntu based) router and have iptables configured to drop all incoming packets by default. To my surprise, running an nmap scan (from the WAN side) shows two open ports related to VOIP:
...
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0answers
127 views
Intercept data after sslstrip
I am able to use sslstrip successfully as shown here https://moxie.org/software/sslstrip/
What I want to do though is be able to use sslstrip with another proxy/script to modify requests/responses ...
1
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0answers
78 views
IPSec and traffic mirroring [closed]
I have a VoIP server on which several SIP clients are connected to through IPSec tunnels.
This is kind of an automated attendant so I both have RTP and SIP signalling flows.
I need to be able to ...
20
votes
2answers
1k views
Fully transparent proxy
By default, mitmproxy will use its own local IP address for its server-side connections. What I want instead is mitmproxy to use the client’s IP address for server-side connections.
The following ...
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4answers
2k views
SIP UDP request breaking through iptables
I have been investigating a few instances recently where SIP UDP traffic has been somehow evading the ruleset defined in iptables leading me to suspect that there is a hole in our rules so i'm looking ...
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1answer
3k views
Can't connect to fake AP with airbase-ng
I use kali-rolling on a virutal machine and I try to set up a fake access point using airbase-ng, but my devices won't connect to it whatsoever. My steps are:
I put my wirless adapter in monitor mode ...
5
votes
3answers
1k views
Does blocking an IP with IP Tables protect you from a DOS (not DDOS) attack?
I am fairly new to network security, and I just learned about the Fail2Ban framework you can use for automated exploit detection/prevention. It says that you can protect yourself from DOS attacks by ...
5
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1answer
2k views
ARP spoofing with Scapy. How does Scapy reroute traffic?
Background:
I understand that in order to ARP spoof a victim in a network using Scapy, we need to send ARP reply packets to the victim and the gateway router with the correct destination and Source ...
0
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1answer
440 views
What is the iptables rule to block all https traffic except to a single ip?
I'm trying to configure a microservice for my web application, which is hosted at ip address X.X.X.X. The microservice should only accept https connections from this web app.
I've tested the ...
2
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1answer
481 views
Security Onion VMWare + OpenWRT IPTables Mirroring
I'm trying to set up SO in my home network to lab and see if I can monitor all ingress/egress traffic from my SOHO router. I don't have a switch with SPAN ports, or a network tap so I'm using OpenWRT ...
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1answer
876 views
Can iptables be hacked / circumvented
We currently have a server that blocks all connections using iptables, and we have to whitelist an IP expressly in order to be able to access the server remotely.
Essentially, the first rule allows ...
2
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1answer
296 views
Iptables DROPS SSH after port knock rules, but nmap shows it as OPEN
I setup port knocking rules on CentOS 7, iptables as follow:
-I INPUT -p tcp --dport 1 -m recent --set --rsource --name KNOCK1 -m limit --limit 5/min -j LOG --log-prefix "knock 1" --log-level 7
-I ...
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0answers
240 views
Exploit vulnerabilty in embedded Linux network stack to disable iptables
I own a D-Link DCS-7110 HD POE network camera.
It features an apparently iptables based access list configuration where you can allow/disallow certain networks and addresses from accessing the camera....
0
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1answer
181 views
Captive Portal Security Measures
I am currently working on a Captive Portal solution, which can be distributed in an device that has an ethernet and wlan port. In short, I use iptables to restrict access to all devices unless they ...
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1answer
376 views
What ports should I filter on a default Magento installation
I have recently installed a Magento on Ubuntu 14.04 on Digital Ocean and I'm wondering what ports should I filter to keep it safe. Well, actually the question should be: what ports I keep open to the ...
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0answers
90 views
How should I manage wireless connections if using iptables?
I am implementing some modest iptables on xubuntu 17.04 and came across this blurb from IptablesHowTo Ubuntu
WARNING: Iptables and NetworkManager can conflict. Also if you are
concerned enough ...
2
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1answer
2k views
MitM-Position with bridged network and iptables
I'm currently trying to get my setup to work.
[ victim ] --- [ mitm ] --- [ net ]
IPs:
net: 10.0.0.0/24
victim: 10.0.0.1
mitm: 10.0.0.2
gateway: 10.0.0.254
setup:
ip l a name br0 type bridge
ip l ...
0
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1answer
346 views
How to block an application with iptable which use random port
Scenario:
My goal was to allow TeamViewer to connect to my home workstation from my laptop only. So I have tried to bind my laptop's MAC with an IPtables rule as following,
[arif@arif:~]$ sudo ...
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0answers
1k views
Creating a rogue AP with Kali Linux
so i have for the last 2 days going through this task of setting up a Rogue AP on my Kali linux running in my VM.... i am using the 64bit version and the wifi adapter is TP link TL WN722N, so my ...
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1answer
330 views
What is the most secure communication between firewall, and DMZ
I have 2 virtual machines. (Vmware esxi 6)
They are both opensuse 42.3 (tumbleweed)
Firewall (iptables,ipset,dhcpd,dns only)
mail/web server. (apache,dovecot,postfix)
The web server can not ...
2
votes
1answer
937 views
Is a Captive Portal Wifi AP as insecure as an open unencrypted Wifi?
As far as I understand, the captive portal is implemented by some sort of iptable firewall rules. Since there is no handshake established during the initial association with the AP(As no passphrase is ...
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0answers
203 views
Why is Skype traffic not passing through the NAT table of the PREROUTING chain in iptables?
I have successfully performed a MITM attack and have managed to view the HTTP/HTTPS packets of the victim passing through the nat table of the PREROUTING chain of my iptables.(using -j LOG) However, ...
8
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1answer
3k views
Nmap - Intense vs Quick result
I inherited a small network and currently am assessing its security performance.
I started port scanning a host (lets call it Weirdo) in that small network and from my perspective, it seems that that ...
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1answer
199 views
Which chain of the iptables receives the sniffed packets
Host C is using wireshark to sniff packets from Host A to Host B. I am able to see those packets from wireshark but I am not able to find them in the PREROUTING chain of iptables. When Host C ...
0
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2answers
144 views
Using IPTables over a network [closed]
I recently found out how to "block" an IP address from your computer, with this command:
sudo iptables -A INPUT -s 210.1.193.49 -j DROP #Blocks 210.1.193.49 from your computer
I was wondering, how ...
