Tagged Questions

A firewall is a program that controls the incoming and outgoing network traffic on a system. Use this tag for all questions related to firewall configuration and operation.

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3
votes
1answer
403 views

Can I limit connections per second for certain UserAgents using UFW?

GoogleBot is hitting my server hard - and even though I have set the CrawlRate in Webmaster Tools it is still hiking up the load on my server and slowing down Apache for the rest of the normal web ...
4
votes
1answer
4k views

How to understand why the packet was considered INVALID by the `iptables`?

I set up some iptables rules so it logs and drops the packets that are INVALID (--state INVALID). Reading the logs how can I understand why the packet was considered invalid? For example, the ...
1
vote
1answer
328 views

Firewall/routing rule in Centos for this setup

I have two ethernet interfaces, namely eth0 and eth1. I want to implement an advanced routing rule but I am totally new to firewall/routing rules in CentOS. Here is what I am trying to do: Both my ...
0
votes
1answer
677 views

Allow incoming connections from Google Translate only

I have a small web server running on port 80, and I'd like to allow only Google Translate to have access to it. First I tried running dig translate.google.com and dig translate.googleusercontent.com ...
3
votes
3answers
918 views

Can't add large number of rules to iptables

I made a very simple bash script (echo at start, runs commands, echos at end) to add approx 7300 rules to iptables blocking much of China and Russia, however it gets through adding approximately 400 ...
4
votes
1answer
3k views

nmap shows me that one service is “open|filtered” while locally it's “open”, how to open?

I have a Quake 3 server. And it's launched successfully. The problem is that no one can connect to that server. I am running: nmap -sU -p 27960 hostname and it's showing me that it's state ...
1
vote
3answers
13k views

How to block https facebook site using iptables [duplicate]

Possible Duplicate: iptables to block https websites I am using Zentyal Os as a firewall, it working fine like blocking http sites and but I am not able to block https facebook site. My ...
1
vote
0answers
137 views

Perform Cisco's DNS Doctoring on FreeBSD

How to perform a change in the DNS response from a DNS server to be a different IP address than the DNS server actually answered for a given name? ...
3
votes
3answers
2k views

MySQL Linux Client Timeout/Keepalive

Is there a way to set a keepalive in the command-line MySQL client on Linux? Our network recently moved to a VLAN setup, and our systems department no longer has control of the firewall. The ...
5
votes
1answer
3k views

Enable RTSP in iptables

I'd like to receive a RTSP stream via VLC, but when I try to run sudo -u non_root_user cvlc -vvv -I dummy rtsp://ip:port/x.sdp I get: Unable to determine our source address: This computer has an ...
2
votes
1answer
355 views

Make box only communicate on lan only?

I am running a VM with Debian as the guest OS (I can choose another distro). It has nginx running along with some other software. Some of the software tries to make outgoing connections (for example ...
1
vote
0answers
136 views

What other rules should I use to allow PPTP outbound connection?

I already allowed outbound connection to TCP/UDP port number 1723, but PPTP connection still fail to establish, If I allow all outbound connection, the tunnel will just go fine.
4
votes
1answer
691 views

How to “jail” a user account's network capabilities on Linux?

Linux box a is connected to a home DSL line with dynamic DNS registration, hosting a tmux session to which multiple clients connect in read-only mode over SSH. All users connect using the same ...
3
votes
1answer
774 views

Changing firewall settings after installation of CentOS via kickstart

I was trying to install CentOS 6.3 via Windows Deployment Server. And to automate the installation process I used kickstart file in which i provided various details required during installation.Then i ...
51
votes
4answers
28k views

How does reverse SSH tunneling work?

As I understand this, firewalls (assuming default settings) deny all incoming traffic that has no prior corresponding outgoing traffic. Based on Reversing an ssh connection and SSH Tunneling Made ...
4
votes
1answer
4k views

How to configure pfsense to NAT servers?

How can I configure pfsense so it will NAT servers so they can be accessed outside of the company? I tried to play around with the NAT settings, but didn't get anywhere. I want to be able to access ...
4
votes
2answers
816 views

NAT and source IP filtering in PF, using OpenBSD >= 4.7

I just read a book about PF (The Book Of PF, No Starch), but there's one question not answered by it. If I have a gateway machine using two interfaces, $int_if and $ext_if, and I NAT the packages ...
6
votes
3answers
8k views

What prevents a machine from responding to pings?

I have a CentOS release 5.4 linux box on Amazon EC2 that I'm trying to set up to be monitored via Nagios. The machine is in the same security group as the nagios server, but it seems to be ...
4
votes
1answer
2k views

Is berkeley packet filter ported to linux?

I am doing some research to figure out what distro's of linux contain kernel packet filtering and are compatible with BPF. http://kernelnewbies.org/Linux_3.0 http://lwn.net/Articles/437981/ These ...
1
vote
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 ...
3
votes
2answers
987 views

How to Add rules to IP Filter (Firewall in SCO)

I need to add a rule (allow any to any port 22) to my firewall, so that I can ssh remotely into my machine. I have had a look in the SCO OSR600 Documentation and I cannot find anything in there that ...
1
vote
2answers
2k views

How to allow mysql remote connections via particular interface

I have a 10.237.49.251 IP on eth0 and another IP on another interface How do I enable remote mysql calls on eth0 device?
2
votes
2answers
1k views

What is a solid iptables configuration for my desktop?

On my desktop, I want to configure iptables pretty strictly. I see no reason why I need to allow anything except for internet traffic that I initiated. And maybe even that could be limited to only a ...
0
votes
1answer
1k views

Network Printing in Fedora

I´m having problems setting up network printing in Fedora 16. In the printer setup box it says FirewallD is not running and gives a list of protocols that need to be enabled. I cannot find a FirewallD ...
5
votes
1answer
5k views

Uncomplicated Firewall (UFW) and UPNP

Is it possible to configured UFW to allow UPNP between computers in the home network? Everything works if I turn off the firewall. I can see in syslog the firewall is blocking me. I've tried all ...
0
votes
2answers
2k views

How to set up firewall on Debian Squeeze

I have set up Apache, MySQL, PHP, SSH (which I use to connect to the VPS), Node.js, MongoDB and ProFTPd. Now, I want to have a firewall on the system, so that no one hacks the system. For instance, ...
0
votes
1answer
3k views

IPtables string match

I'm trying to write iptables string match rule To block http://domain.com:8888 and https://domain.com:8888 when it matches the supplied string in the rule. And another rule to redirect the ports also ...
1
vote
1answer
159 views

Linux tools to choose suitable Cisco ASA 5500

I have a linux webhosting server which attracts DDOS attacks. I want to use Cisco ASA 5500 Series Adaptive Security Appliances to protect the linux server from them. I know there are many factors ...
0
votes
2answers
191 views

How To See Which Ports Are Open On A Particular Firewall

Using the terminal I was wondering if it would be possible to see a list of all the active firewalls on a particular system that I have shelled into. I want to be able to see which ports are active ...
1
vote
1answer
443 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 ...
5
votes
0answers
2k views

Installing pfSense firewall on an SSD

I was looking at creating a home firewall running pfSense (as I could not get IPCop to boot properly on my hardware). Doing a little research, however, I have some concerns with installing it onto an ...
3
votes
1answer
644 views

Linux Home Firewall

I was recently delving into thoughts of building a small home server to run random things off of (maybe a TF2 server). Thinking about this further I realized I would need to get a better firewall ...
1
vote
1answer
191 views

iptable rule to redirect only https handshake?

I was reading this interesting article today: http://www.moserware.com/2009/06/first-few-milliseconds-of-https.html A crazy thought came to mind...Is it possible to write an iptable rule that only ...
5
votes
2answers
2k views

Preventing program from using internet

Is there a way to block certain programs from being able to connect to the internet in Debian (a firewall blocking outgoing connections), so for example, to block a windows program running in wine ...
8
votes
4answers
801 views

iptables on tor exit node

I want to run an open Tor router. My exit policy will be similar to ReducedExitPolicy. But I also want to make it hard for the tor network to abuse my resources. Cases I want to prevent clients ...
4
votes
1answer
974 views

Outgoing firewall application similar to Little Snitch for Mac

Is there a Linux application similar to Little Snitch? Little Snitch is an outgoing firewall that temporarily blocks outgoing network requests until the user decides whether to allow the connection or ...
2
votes
2answers
1k views

Can I use divert as an alternative to ipfw fwd?

I would like to lead some traffic through a transparent proxy (which actually is on another server and connected with an ssh tunnel). Normally I could do this: ipfw add forward localhost,8080 tcp ...
-2
votes
4answers
241 views

Steps to secure your server? [duplicate]

Possible Duplicate: What to use to harden Linux box? Apparmor, SELinux, grsecurity, SMACK, chroot? I'm just completed install my web server. So what should i do to secure it? I just ...
8
votes
2answers
9k views

How can I block a range of IP addresses with an Amazon EC2 instance?

I know a certain range of IP addresses are causing problem with my server, 172.64.*.* what is the best way to block access to my Amazon EC2 instance? Is there a way to do this using security groups or ...
12
votes
2answers
4k views

Per process firewall?

I've been reading around but can't seem to find a way to create per-process firewall rules. I know about iptables --uid-owner but that only works for outgoing traffic. I've considered scripting ...
2
votes
0answers
798 views

pfsense long ping to google

I have a pfsense box set up. What happens is I set a rule so I can't hit the admin interface 192.168.3.1 from the box. With the rule enabled --- www.l.google.com ping statistics --- 2 packets ...
11
votes
4answers
2k views

Why do we need a firewall if no programs are running on your ports?

When I try to telnet to a port on a server, and if there is no program listening on that port telnet dies with a "Unable to connect ... " error. I understand that. But, why do we need a firewall if ...
3
votes
2answers
986 views

How to check and block processes connecting to internet directly?

Is there a way to find which processes in my system are getting connected to net automatically. Is there a way to select and block net access of some processes permanently? I use mint 11. I use a USB ...
2
votes
1answer
661 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 ...
3
votes
1answer
428 views

What port range will ipfw nat use for aliasing?

I am using ipfw nat with the following config ipfw -q nat 1 config if em0 Which TCP and UDP ranges will the NAT choose its alias ports from? I would like it to be always from the range 49152–65535, ...
3
votes
2answers
769 views

FreeBSD kernel nat or natd?

As I notice more often with FreeBSD, there are always plenty of ways that lead to some specific goal. After figuring out which firewall I wanted (I choose ipfw) I now am completely insecure about ...
3
votes
3answers
4k views

Blocking outgoing connects with iptables

I have a (non production) machine where external supporters have shell-access (non-root). I want to prevent them from going further on into our network from that machine using iptables. The "normal" ...
5
votes
1answer
5k views

Ignore a specific ip for fail2ban

I am using fail2ban with ipfw on FreeBSD. Is there a way to ignore a specific ip address, making sure that fail2ban never blocks or reports it?
2
votes
1answer
485 views

UFW Limit does not appear to work

I have my ssh port changed to XXX. Then I did ufw limit XXX/tcp However, when I try to login, after 5/6 failed attempts I get thrown back to prompt, but I can try again. Is that supposed to be the ...
2
votes
3answers
2k views

Making sense of auth log

I am seeing some log enties that look like hacking attempts Type 1 Dec 26 03:09:01 ... CRON[9271]: pam_unix(cron:session): session closed for user root Dec 26 03:17:01 ... CRON[9308]: ...