General :: Block UDP Protocols In Iptables - Ubuntu ?
Aug 5, 2010
Currently I have 2 Lan card in My System one for communicate client pcs (Lan card Ip 192.168.1.100) and other for Internet (Lan card ip 192.168.0.100.) All client pcs are in 192.168.1.0 Subnet
Here i implement my system as router through iptables all clients are communicate through only 192.168.1.100 (clients default gateway also 192.168.1.100) Now no problem for forward rules when my system is active all clients are get internet.
Now i have problem with blocking UDP protocols i tried lot of things in net iptables -A INPUT -s 192.168.1.0/255.255.255.0 -p UDP -j DROP
But it's not blocking UDP protocols (i change UDP to ICMP Protocols then icmp is blocked every ip address)
The ip_blacklist chain is used to immediately drop any traffic from specified address ranges, while the tcp_, udp_, and icmp_packets chains contain rules for further processing of those protocols. The last rule in each of the latter three chains drops all packets that didn't match any rules above it; so tcp, udp, and icmp packets should NOT get caught by the default INPUT policy (DROP). The goal of the last rule on the INPUT chain is to then log any packets that are picked up by the default policy. However, it's not working.
I can tell that there are packets being picked off by the default policy because the counters are being incremented, but nothing is logged by that last rule. My conclusion is that it's only looking for tcp, udp, and icmp packets and ignoring everything else.
How to get iptables to log all the other protocols (or whatever is being caught by the default policy)?
Currently I have 2 Lan card in My System one for communicate client pcs (Lan card Ip 192.168.1.100) and other for Internet (Lan card ip 192.168.0.100.) All client pcs are in 192.168.1.0 Subnet Here i implement my system as router through iptables all clients are communicate through only 192.168.1.100 (clients default gateway also 192.168.1.100) Now no problem for forward rules when my system is active all clients are get internet.
Now i want to block some ip address and port ways i tried lot of things in internet when i type iptables -A INPUT -s 192.168.1.150 -j REJECT (i found in internet it will block that ip address for getting internet and any access through my sys)
I have blocked below IP by using iptables command in RedHat Linux 4.0.
Code:
iptables -A INPUT -s 192.168.0.85 -j DROP
It's now totally blocked and can't get access into web or internal network. how I can un-block that IP, so that it can again starts it's normal operation.
I want to block all outgoing traffic with iptables and only allow a few specific websites. I would like to get the code to do so and also to revert the changes in case I want to unblock them.
in my office i have to block all messenger like yahoo messenger, windows live messenger, i have to block websites like www.yahoo.com, some more web sites. i need guidance through which i can accomplish this task through ip tables or through squid server. i can use squid but i had heard that squid blocks pop and smtp also. squid creates some problem in receiving and sending email. i am using red hat linux 4 box and installed squid having two ethernet card 1 is connected to adsl line and 2 is connected to switch. all clients will have proxy address of this linux box. guys need ur help ASAP.
I would like to allow incoming and outgoing connections when I'm connected to a wired connection, but drop it otherwise. I noticed that ufw can't block outgoing traffic because of will I give iptables a try. I'm unsure if dropping packages that are outgoing will work, the rule after the block rule will allow all outgoing connections.
This what the rules are intended to do, unsure if that is actually the case. Allow all loopback traffic. Allow ping replys Allow incoming on port 12345 if eth0, deny otherwise. Allow outgoing on port 12346 if eth0, deny otherwise.
Code: iptables -A FORWARD -j DROP iptables -A INPUT -i lo -j ACCEPT iptables -A INPUT -p icmp --icmp-type 0 -s -m state --state ESTABLISHED,RELATED -j ACCEPT
My VPS host a mail, blog and web site. So i want to block port i not use. The port that i use is 80,21,2022,443. The other port will be drop. I want to block bad packet and all packet that not related. Can anyone how to write in iptables?
I have the requirement that if our website receives 20 or more requests within 60 seconds, to block the offending IP address for 5 minutes, then allow them access again. My only certain mechanism to do this is iptables. I wrote the following series of commands:
I have a Suse 10.3 router with 4 network cards. 1 is to connect to the big network and thereby also the internet, 2 are for 'client' subnets and I want to use the last one as a DMZ. In this DMZ will be a web server which has to be accessible from the other 2 subnets and from the big network. I could do it with a few simple clicks in Yast firewall, but I have some issues with this firewall and there for I want to use it as minimal as possible, using Iptables.
So now I'm struggling a bit with Iptables. Basicly what I'm looking for is how to block all ports but 80 in this last subnet with iptables.
I keep getting hundreds of SSH failed logins per day. Is there a way with iptables, i can say if a user connects too to port 22 over 8 times in 10 minuntes, then block them for an hour?
I Need to know how to block this applications using iptables or ROPE scriptable Method..?..
1.Web navigation 2.Electronic mail 3.FTP transfers 4.Video traffic (multicast video stream and unicast video stream) 5.VoIP service 6.Instant Message (MSN and yahoo messenger�etc) 7.Management service (TR-069 and SNMP)
I Need to know how to block this applications using iptables or ROPE scriptable Method..?..
1.Web navigation 2.Electronic mail 3.FTP transfers 4.Video traffic (multicast video stream and unicast video stream) 5.VoIP service 6.Instant Message (MSN and yahoo messenger�etc) 7.Management service (TR-069 and SNMP)
I run a small home server (Debian 4), which acts as my gateway to the internet (ie, firewall) and runs a web server, dhcp, dns, and acts as a file server to the rest of the machines on my home network. Now I know it's never a smart idea to have all those services running on the same machine that is acting as a firewall, but I don't fancy running multiple servers just for home use, as it's mainly allowing me to learn system administration.
I noticed a few days ago that my internet had become unbearably slow, to the point where I could sometimes not load web pages. I spent a while searching through log files on my gateway, to try and find out what was eating up all of my bandwidth. When I came to apache's access.log file, I was confronted with this:
Multiple requests to my server, for totally random websites. I didn't even know it was possible to make those types of queries to a webserver. The only thing that is on the web server is a browser based torrent client. I have only shown a small snippet of the log file, but there are around 90k lines to different web addresses, from many different IPs. What I want to know, is what is happening? :S Why is someone querying MY web server, for web sites totally unrelated to it? And most of all, how can I stop it. My initial was to try and use iptables to block multiple requests from the same ip within a certain time frame, which I think would work as the server shouldn't really get many queries from external networks.
I was trying to write IPTABLES script to block the ICMP ping using the below mentioned command in OpenSUSE 11.2 Doing this in VMware.....
iptables -A OUTPUT -o eth0 -p icmp -j DROP
& then I tried to ping the different computer & it didnt allow me to ping. Then I deleted using the command -
iptables -D OUTPUT -o eth0 -p icmp -j DROP
then I couldnt ping also. Another thing I found is my firefox is not connecting to the internet as well, but before writing the script, I can connect to internet.
I m pretty new to Linux..! I've been given a task to modify network protocol(TCP in particular). So now i've to make few changes to the kernel which includes modifying few source files. So i want to know how can i go abt it. Till now i've explored various .c files of kernel(Eg.tcp.c,tcp_input.c etc etc)by referring few books. And now comes the important part of implementing it. So how exactly can i go abt it?? I went thru various threads like installing a kernel,compliling a kernel and other things. But i m not getting the exact sequence in which i should do it. I've installed fedora 10. But i cannot see any source files which i can modify. Where and how can i modify these files?
I want to connect my Debian Squeeze machine to my school wireless network with wpa_supplicant.
I think the network uses 802.1X authentication, because when the other students connects to the network for the first time in Windows they enter their username and password then the connection is established. I have asked the the IT staff but they do not known what 802.1X, PEAP EAP etc. is and just say "Enter the login details in the box!".
If I bring a Windows 7 machine to school and successful connects to the network, is it then possible for me to extract the information [and extract a certificate if used on the network] from Windows somehow so i can setup the wpa_supplicant.conf correctly on Debian?
The information I want to extract is which protocols are used, like PEAP,MSCHAP etc.
I am facing a strange problem witht my iptables as there are some firewall entries stored somewhere which is displaying the below firewall entries even after flushing the iptables & when I restart the iptables service then the firewall entries are again shown in my iptables as shown below,
