A Firewall is an application or hardware device used to inspect and filter network traffic.

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Should I create a second WAN Interface for a new SSLVPN setup on my Sonicwall 2400?

Sonic Wall 2400 I'm setting up a new SSLVPN on our Sonicwall, very new to this. I currently have an exchange server as well, so mail.company.com is directed to our mail server. I'd like to setup a ...
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How do I block SSH connections except those originating from within a /29 block of IP's or LAN? (CentOS 7 and Ubuntu 12) [on hold]

I see thousands of failed login attempts on our servers and want to do what I can to prevent a successful one from the bad guys. I want to block anyone not originating from a /29 block we own from ...
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Layer 2 OpenVPN Bridge Headaches

I have a "working" layer 2 home->cloud (Vultr) bridge over OpenVPN. On both ends is an OPNSense firewall (since pfSense doesn't plan to switch to libreSSL due to "rude forking" by the libreSSL devs). ...
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2answers
2k views

Smoothwall Express interface issues

I have a SmoothWall Express box that is currently configured with a Green and Purple interface. Both interfaces are in the same /24 subnet (which seems odd to me). The green interface (address of ...
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7 views

nginx naxsi $URL_X doesn't work

Recently recompiled my NGINX with a NAXSI module. Now setting up the white lists but the $URL_X functionality doesn't seem to work at all. Generating Incorrect line BasicRule wl:1312 in NGINX ...
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3answers
57 views

Are there any reasons why we should not block unencrypted service ports for mail such as 25,110 & 143?

I want to block smtp 25, pop 110 & imap 143 and only use secured smtps 465, pop3s 995 & imaps 993. Are there good reasons to let port 25,110,143 open?
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Linux: Invalid TCP Flags

It is often recommended in tutorials and books to filter invalid TCP flags with iptables. I wonder if those aren't already filtered by the kernel itself or the iptables state module. Does anyone have ...
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13 views

UFW - Set correct kernel params

As every system administrator does, one of the first things i did right after booting up my web server was install ufw and tune/set kernel parameters in /etc/sysctl.conf. By the way, this is my ...
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11 views

Block connection through proxy in firewall [duplicate]

I'm getting some 'ddos' on my Linux machine (ubuntu 14.04 64bit). I have a lot of connections from IP which are proxy IP's (like tor), on specific port. Question: How to block all proxy connections ...
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Windows equivalent of iptables?

Dumb question: Is there an equivalent of iptables on Windows? Could I install one via cygwin? The real question: how can I accomplish on Windows what I can accomplish via iptables? Just looking for ...
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1answer
13 views

How do I block an abusive IP address using a Netgear FVS338 firewall?

Our Postfix mailserver has been getting thousands of automated login attempts from a bot. The mailserver is behind a Netgear FVS338 firewall. How can I completely block inbound connections from that ...
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3answers
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WMI: How can I fix the port?

I need to use WMI for getting some information from my servers. But I have a server in DMZ, so I need to open a port in my firewall. I've searching and I found that WMI uses random port. How can this ...
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17 views

vpn session over http or https [on hold]

I can only access http://site.example.com or https://site.example.com (running linux centos behind ddwrt router) the http firewall allows those virtualhostnames to connect to the client (me) but not ...
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1answer
21 views

OpenVPN: restrict a client to certain IP addresses

I have an OpenVPN system with a number of users. I need to restrict some of the users so they can only connect from certain source IP addresses. It's not possible to simply firewall the OpenVPN port ...
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1answer
44 views

pfSense can't access https website

I have just installed pfSense on a PC Engines APU1D4 to evaluate as an alternative to a Soekris 5501 + OpenBSD based setup, I have a PPPoE WAN configuration. The pf rules, NAT and PPPoE ...
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14 views

How to block a router on local network hogging me with mDNSResponder [closed]

I'm on a local network, connected with LAN. There's an annoying router on the same network (which I don't use), which is making five requests per second to my computer with mDNSResponder. I know ...
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2answers
44 views

Cannot ping centos7 host

I am doing this for the first time, so I may be missing something very basic. I installed Centos 7 on a new server and have successfully gotten the connectivity working. Now I want to be able to ssh ...
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1answer
21 views

How to verify that a firewall closes inactive connections?

How can I verify that a firewall closes connections on port X to a server after N minutes of inactivity? Background: I am working on a Java EE application deployed to a Glassfish application server. ...
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3answers
5k views

Configure multiple lan interfaces for same subnet on sonicwall

We have a sonicwall 2400, Is there any way to assign multiple interfaces to the same lan subnet? Basically, we would like to have X1 for the wan and X0, X2, X3 and X4 connected to 4 devices that would ...
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1answer
1k views

Ubuntu 12.04 open port 80 inside VLAN

I have an nginx server running on ubuntu 12.04 that serves http through port 80 and https through port 443. Everything works fine if I access it from the same computer via localhost, 127.0.0.1 or the ...
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1answer
3k views

Watchguard config, drop-in or mixed-routing mode?

I have a Watchguard XTM 2 that is currently acting as a firewall and a router for my business network, I currently have the WG setup in mixed-routing mode and am happy with the current configuration. ...
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1answer
8k views

PPTP connection fails with errors 800/806

I've got a client (Server 2008 R2) that won't connect to our production environment PPTP VPN server (Server 2003, running RRAS). The server is behind a firewall that has TCP1723 open as well as GRE. ...
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19 views

General matter of stateful iptables

I made a set of stateful iptables rules which only handle accepted traffic (More or less). The workflow can be seen in the image below. My questions are: Is it a good idea to drop INVALID state or ...
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1answer
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Server 2012 R2 TCP Timestamps

We will be having some penetration testing performed shortly and looking to clean up a few things. One of these is TCP timstamps in Windows. A simiple NMAP scan shows me a guess of the TCP timestamp ...
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3answers
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Should I rate-limit packets with iptables?

I'm using iptables on Ubuntu Server. It's a web server on a VPS. I'd like to know if I should rate-limit packets. If so, what should I rate-limit? And should I do so globally or per IP address? ...
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2answers
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Juniper SSG5 DHCP IP Pool is full. Unable to offer IP address to client

hope we have some Juniper guys around, I have configured a Juniper SSG5 as our main firewall/router the DHCP server set on interface bgroup1 to have a rang from 10.10.10.76 to 10.10.10.210 All ...
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5answers
156 views

How do I detect TCP requests coming from my linux machine getting stopped by a firewall?

I have an application that is getting blocked by a firewall but not logging failures to any type of log. I've since opened the hole in the firewall, but is there a good way to see what the actual ...
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4answers
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How do you PREPEND an iptables rather than APPEND?

Pretty basic question.. How do you PREPEND an iptables rather than APPEND? I have DROP statements at the bottom of my rules. I have software to add new rules but adding rules after DROP statements ...
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1answer
15 views

How can I add rule to iptables on ubuntu to enable redis on local ip but not external

I've followed the various scripts to set up 2 linode machines. Both have an external and local Ip. On one I have installed redis, and I want to connect to this machine via the local ip. Which rules ...
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17 views

iptables hex string match rule migrate to Vyatta (BROCADE)

I have a string match, drop rule working in iptables firewall that I would like to migrate to a Vyatta firewall. Is string matching even possible in Vyatta? If so how can I replicate the following ...
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2answers
27 views

How to list open but not used (by a process/program) port?

I have a VPS with debian wheezy installed on it. A firewall is active on the it with all ports not allowed by default. The firewall can be managed through the web interface of the provider of the VPS ...
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22 views

Block redirected port from external access using ufw

I have an application that uses ftp. I redirected the 21 port to 2221. But I see that 2221 is accessible from external even though it is not specified in ufw rules. So I want to block 2221 from ...
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1answer
947 views

Deploy Advanced Firewall Rules via GPO - How to avoid merging?

I am trying to deploy a set of advanced windows firewall ACLs to several 2008 R2 servers. I would like to (i have to) ensure that no local or old rules are getting applied. So I set "Apply local ...
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0answers
15 views

How To Stop Apache Logging Client Denied By Server Errors [duplicate]

I get an annoying amount of spam traffic from the Ukrane, Russia, Korea etc. I have setup rules in my .htaccess file to block all of these countries and it's working great. The problem i have now is ...
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1answer
33 views

pf firewall server configuration

I am trying to configure a fire wall for a server that host http, smtp and ssh on a custom port. When I initialize pf, I get an error at the command line: No ALTQ support in kernel and my ssh ...
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27 views

Use extra firewall to filter WAN traffic before reaching UTM?

I am running a simple web server behind UTM, only port 80,443 is open. However almost 80% of the traffic coming through WAN is trouble. Mostly are port scanners / sniffers or systematically querying ...
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2answers
33 views

prevent openvpn client from changing ip of tap device

I have an openvpn server behind a firewall, clients are assigned static IP addresses with specific ifconfig-push directives in the client-config-dir. The problem is that clients can change their ...
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2answers
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In the output of `last`, what does suffix “.d” after an IP address mean?

In order to find out who was logged in recently on my server I am using the command: There were logins from very strange IP addresses e.g.: username@pc:/home/user$ last username pts/16 ...
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1answer
3k views

iptables forward rule not working in openwrt

I am trying to apply some iptables forwarding rules in openwrt. Here is my scenario - My server has two cards ath0 and br-lan. br-lan is connected to internet and ath0 to private network. The other ...
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1answer
3k views

Open port 8009/tcp on Fortigate necessary?

A nmap scan of a Fortigate Firewall showed that TCP port 8009 open is. According to knowledge base articles this is only to download the client for ssl vpn. Is this port used for anything else, and if ...
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1answer
16k views

Why would the servers network type change from Private to Public?

Just found a fault with a server, other users have had problems connecting to it. The setting on the network card had changed from Private (domain) network to Public (the other option being Home). ...
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ASA 9.1 NAT Rule issues

I added this NAT rule on my 5510 ASA object network SHF-NY-DC01 host 192.168.1.50 nat (Inside,Outside) static interface service tcp ldap 6699 access-list inbound extended permit tcp any object ...
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1answer
33 views

blocked DNS traffic on GCE?

I am trying to setup DNS server on an Ubuntu 14.04 VM on Google Compute Engine. It looks like queries to the DNS server are not reaching the VM even though I have allowed TCP/UDP traffic on port 53 ...
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4answers
2k views

Sonicwall NSA2400 - No internet access

We've got a SonicWall NSA2400 configured with a LAN (X0) and a WAN(X1) interface. It was setup and working fine until just recently when a temporary worker changed some settings most likely NAT. We ...
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Understanding packets dropped by iptables from puppetmaster

I am seeing packets getting dropped during my puppet client runs on a semi regular basis. And I do not understand what is causing this. I should mention that Puppet is managing the firewall rules ...
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1answer
31 views

Remote WOL over CISCO/FW not Forwarding

I'm trying to accomplish a Wake-on-LAN by triggering the two servers' public IP addresses. Internally, the WOL works like a charm (by either the internal or external IP), externally however, it does ...
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1answer
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ZenOSS webinterface connecting

I'm having a problem with ZenOss. I installed the centos stack installer on Centos 5.5 x64. De installation succeeded and no errors where displayed. But when I tried to surft to the ip address it ...
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1answer
50 views

Too many open connections [duplicate]

I have a dedicated server with 32GB RAM. It works all fine till some punters came to ddos my server. I had really high uplink bandwidth usage (over 150Mbps). I looked at netstat with the following ...
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1answer
33 views

Vsftpd usually works but sometimes gives FAIL DOWNLOAD on Ubuntu

I have a Virtual Private Server running Ubuntu 14.04 LTS minimal system (64-bit). I have successfully installed and set up Vsftpd which serves images to my mobile app (the app uses the Apache Commons ...
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1answer
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How to unblock service discovery for IPv4 via Avahi?

On a Debian 6.0.6 system (squeeze) I am having trouble resolving a host using Avahi and IPv4. Here is a sample output: : nr@homedog 10102 ; avahi-browse -a + eth0 IPv6 yorkie [00:1f:3b:d8:67:1d] ...