Security :: Iptables - Logging All Protocols - Not Just Tcp - Udp - Icmp
Jun 21, 2010
Brief overview of my current setup:
Code:
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)?
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May 21, 2011
I am setting up a virtual server. Ubuntu 11.04, "minimal provider image".UFW was disabled by default. I set it to default deny. Allowed HTTP, SSH and other standard stuff, and enabled it. All seems to be OK. Adding one rule to block some annoying security scanners causes ping not to work. I'm not an Iptables expert, but it looks OK to me. I got it from some website, rather than invented it myself, but modified to to fit the ufw config file syntax. What in that rule prevents pings?!? It seems completely unrelated.
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Mar 28, 2011
I am wondering if it's possible to log the number of bytes a connection transfered when the connection is complete with iptables. I know I've seen this sort of information in Cisco FWSM logs, where the "Teardown" entry of the logs has the bytes transferred for that connection. Is it possible to have something similar to that with iptables? Where the initial connection attempt is logged (i.e. NEW, which I have logging fine) AND an entry for that connection that includes the bytes transferred?
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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)
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Nov 12, 2009
I want to block the icmp packets(ping) from the other computer to my RHEL-4 what's the syntax I should use to do so in IPTABLES.
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Aug 5, 2010
In Lucid I have some ufw rules but I figured that I need to limit the ICMP messages that the box responds to and also limit their number. There are iptables rules to accomplish this but since I already have ufw rules it is safe to use iptables only for ICMP rules ?
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Mar 13, 2010
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 did a "dhclient" & iptables -F....
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May 17, 2009
I would like to allow multi users to access P2P networks, so I wonder if there's a way to tracking these kind of protocols with netfilter, and also compatibility with nat, like the module conntrack_ftp seems to do with the FTP protocol.
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Aug 27, 2009
I was having a discussion with someone who said that telnet, FTP, HTTP plain-text authentication in the local subnet is ok because it's a switched network. Also, that these protocols are not good over the net but in a local subnet they are just fine.
I know that someone can plug a hub in the network port and connect 2 (or more) PCs and see the packets. Also, heard about ettercap but haven't really delved into it. I know dsniff was written to prove the point that unencrypted protocols are bad. Would like to get opinion about unencrypted protocols over a switched networks.
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Dec 9, 2010
I need to allow ICMP ping for one host only. I found out how to enable it to all hosts (ICMP Filtering, check ping) but I would like to reduce the scope to one host. I know I can add rules in the user_post script but I can't find the correct iptables command ...
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Apr 6, 2011
i have configured racoon (ipsec tunnel) between 2 hosts and i am afraid of unencrypted ICMP which appears in TCPDUMP logs. There ale also encrypted ESP packets. Is this result of wrong racoon configuration?
172.16.220.133
Code:
[root@localhost ~]# cat /etc/racoon/racoon.conf
# racoon.conf
path pre_shared_key "/etc/racoon/psk.txt" ;
remote anonymous
[Code]...
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Apr 30, 2010
i've tried blocking ping requests with iptables.. and it didnt work Quote: iptables -A INPUT -p icmp --icmp-type echo-request -j DROP
also tried editing sysctl.conf.. which worked perfectly but after i restarted the system i was able to ping my ubuntu machine from my lappy here is what i added to sysctl.conf and then executed it with sysctl -p
Quote: net.ipv4.icmp_echo_ignore_all = 1 here is another atempt to block.. this one worked too... but again after the restart i was able to ping my machine.. Quote: echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_all
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Jul 12, 2010
I've been trying to configure ufw to drop ping requests for a couple days now, and I can't figure it out. I've tried a couple different methods in some different guides, still nothing. Anyone know how to do this?
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Jul 21, 2010
Whether I use ufw or firestarter to populate my iptables, my firewall logs get written to 3 different log files:/var/log/messages/var/log/kern.log/var/log/syslogI want to keep the logging turned on, but I'd rather it not log to syslog, as it's obscuring other events in syslog that I'd like to see. I'm using rsyslog on Ubuntu. I looked around online and found one person suggesting I add this to the top of rsyslog.conf:kern.* -/var/log/kern.logkern.* ~I did that and restarted rsyslog, but it's still logging to the same 3 files.
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Aug 6, 2010
Im stuck on why iptables wont log to syslog.Syslog is working fine and log every other event on the server.Here is my Configs:
/etc/syslog.conf
Code:
*.* /var/log/iptables
[code]...
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Mar 8, 2010
I'm having a lot of problems getting NIS set up with our firewall. I've looked online and no one seems to have any answers. When the firewall is off, NIS works. When it's on, it doesn't.I would like to know which ports NIS needs by logging connection attempts on the server, since I would swear the right ports seem open already. Right now I'm using this to generate the log entries:
iptables -I INPUT -m state --state NEW -j LOG --log-prefix "New Connection: "
iptables -I OUTPUT -m state --state NEW -j LOG --log-prefix "New Connection: "
However, I think it must only work for successful connections, because I'm not seeing any new entries when I try running the NIS client on another machine (ypbind).
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Feb 3, 2010
I've set up a transparrent squid box with two nics. Eth1 = Internet eth0= LAN +Dchp my question is, can I log the data usage of a skype call. My proxy server already records all http an https requests but doesn't record some programs like skype. I know that it is not http traffic, but can I tell my system to record data use by an ip address over a nic with the help of iptables for example?
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Jun 4, 2009
if I use the final flag, postfix loggs to /var/log/messages, not to /var/log/maillog.What I am doing wrong?regards ralfHere my config:
options {
sync (0);
time_reopen (10);
[code]....
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Dec 1, 2015
I'm trying to use these cookie cutter rules that I found. But every time I use them, after a few seconds my wifi connection goes dead. The exception was the first time I used then. Which lasted me a couple of minutes.
By dead I mean I can no longer open a webpage or ping google.
iptables -N LOGGING
iptables -A INPUT -j LOGGING
iptables -A OUTPUT -j LOGGING
iptables -A LOGGING -m limit --limit 2/min -j LOG --log-prefix "IPTables-Dropped: " --log-level 4
iptables -A LOGGING -j DROP
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Dec 14, 2010
I'm seeing really bad user login format under a standard installation and am wondering why ubuntu does this as default. I have noticed that the graphical login for gnome sizes itself to accommodate a user's exact password length. This indicates to me that somewhere on the unencrypted part of a standard installation with user encryption contains at least some indication of the content of the password length which seems a security flaw even if not a complete hole, it majorly reduces the number of attempts a cracker would have to cycle through.
And that's assuming that *only* the length is contained. Furthermore it seems that it would be MUCH better to simply display the number of characters entered into the pw field and allowing the gui to expand itself from an fixed size as the field is filled out so the the user still receives visual feedback for entering characters. Either a simple character count display should be entered into the field or a 10 dot to new line so that one can visually quickly count the number enter by multiplying from a 10base graphical observation.
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Oct 19, 2010
As part of server hardening process i would like to know the Best way of System Logging and Auditing.Following pointould be taken into consideration.Logging of critical eventsLogging access to critical accountsSecure storage and availability of logsReview of logsSecurity of logs
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Apr 26, 2010
Where I work we have a lan, it is almost 100% windows machines except for 2 CentOS machines in which some clients connect to, via VPN. (very small network, <50 ip's used)
I would like to know if there is a way to block access from that machines to others in the network. I'm already logging traffic (with IPTraff) to see if they're accessing other machines in the network others than the ones they should connect.
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Mar 11, 2010
I've enabled the root account on Ubuntu 9.10, however I want to stop it from being used to login via GDM. 9.10 seems to have a different GDM version, how can I carry this out under 9.10
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Oct 8, 2010
A friend of mine has a private forum setup so he and I can communicate back and forth so we don't have to send emails. The link is a "https://" so I'm assuming it's secure. I'm a newbie to ubuntu and I have already switch 3 of my computers at home to ubuntu.
I'm using Ubuntu 10.04 and google chrome as my browser. When I log into his forum it pops up with a screen saying "The site's security certificate is not trusted" and I always click proceed anyways. I'm not worried about this because I'm 110% sure that it's his website that I'm trying to access. My question/problem is it also pops up with a little box telling me to enter my Username and Password every time. When I was using WindowsXP, I had to enter this info once and then I wouldn't have to enter it again.
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Jul 19, 2010
Sitting at the console, I log in with any user name and NO PASSWORD IS REQUESTED. I get logged in automatically without entering the user's password.
I did:
passwd joeuser
To change his password and still he goes right in without being asked for a password!
Possibly related- 10 days ago, my smtp server was breached as a spam relay. The username they cracked was deleted. I added fail2ban for postfix. The logs show no further intrusion.
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Sep 30, 2010
I'm going to start monitoring our Linux servers with a log management/correlation tool to take a proactive approach to the security of our systems.
Right now I'm going to search for log events that include the following:
Any other commands or logs that would be good to correlate or be alerted on when a potential breach or suspicous activity is happening on the box? Logging cleared, permission changes on accounts or particular files or directories? What would you want to see while monioring your servers?
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Oct 18, 2010
I am trying to figure out what command to use to show the number of DROPPED and INVALID packets that the firewall is handling.I'm going to put these commands into a log analyzer script which will run every 15 minutes with cron. The firewall is running and operating the way I want it to. I'm running CentOS 5.4.
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Sep 30, 2010
I need to login as root, or at least get root privileges, in a cron triggered backup run. The straight way to do this would be the backup server making an ssh connection to the server to be backed up (this way because I want to avoid many servers being backed up in parallel and the backup server itself would be managing this diversity), via the rsync command which would be performing the backup's synchronization step.
I'm looking for alternatives to this in some form. I'd like to disallow direct root login to my ssh port (not 22One idea I have is to have the backup server initiate an ssh login as a non-root user, to either the actual source server, or to a server that can reach the source server ... and set up port forwarding. Over the forwarded port, then initiate the rsync that logs in as root via another port that allows direct root, but cannot be reached from the internet at all (because the border firewall doesn't include this port as allowed in).FYI, these logins will be using ssh keys, not passwords. I do need to keep ownership metadata for files being backed up, so this is why I am using root. Also, rsync is needed to get the incremental updates to keep bandwidth usage lower (otherwise I could just transfer a tarball each day).Anyone have any other ideas or comments, for security issues, based on experience doing things like this (backups, routine data replication, etc)?
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Apr 17, 2011
Just had ModSecurity with CRS installed for me on my hosted website, which I'm hardening after a recent hack. My site is a php-based user community with MySQL back end, so people register as members via php.
First, I'd like to properly log malicious activity Then I'd like to deny access where an attack looks likely Thing is, I'm not sure which /etc/apache2/modsecurity_crs modsecurity config files to tweak.then I can't even see my login page because I'm forbidden from the .php file it loads.I'm guessing I need to change rules individually but I have no idea how or which to change to stop attacks. The CRS documentation is just a bit too heavy to give me the basics.
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Feb 22, 2010
I wanted to disable root logins in console, so I searched for that. I found that if I change root's bash to "/sbin/nologin" in "/etc/passwd", root user will not be able to login. So I did that. But when I wanted to use sudo command, it didn't show me root bash, but it only do the same thing as logging in as root in single user mode (shows message that this account is disabled). So, how I can disable root logins, but keep enabled sudo command for standard users?
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