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

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2answers
41 views

DNAT on the POSTROUTING chain

What happens if I try to do a DNAT in the POSTROUTING chain of the NAT table in iptables? Suppose I change the destination IP of the packet in the POSTROUTING chain to an address that should get ...
1
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2answers
55 views

How to limit external access to mail server?

I use Mdaemon mail server. It can be accessed from internal network and from internet (using mail client and web interface). The problem is I need to limit which users can access their mails from ...
0
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2answers
209 views

WatchGuard blocking internal UDP packets

I'm seeing lots of packets that our WatchGuard firewall is dropping. They're all hitting either 255.255.255.255. or 224.0.0.1 using UDP 8612 / 1947 / 17500. Since I've started seeing these messages ...
2
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1answer
116 views

UFW rules in place and enabled yet traffic still allowed

I have UFW configured to try and block some unwanted IPs and associated requests. #ufw status |less Status: active To Action From -- ------ ...
1
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1answer
135 views

Whitebox firewall in datacenter environment

I am looking into alternatives to commercial firewall appliances. Most of the resources available online describe home network firewalls or sub-gigabit networks. Considering than 10GbE is becoming the ...
1
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0answers
15 views

Can a firewall handle packets being sent to it by a network TAP?

We have the intention of examining incoming mails for security purposes. In order to do so we figured out the solution will include: Network TAP - To copy all SMTP traffic to the firewall Firewall - ...
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1answer
48 views

Cannot access IIS Express from another machine

I can access the IIS express website fine from my local machine, either via localhost, or via its IP address. However when I try to browser to that IP address from another machine, it times out. I ...
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1answer
35 views

Barracuda Web Application Firewall WAF - HTTP - Barracuda Does Not Filter Links Clicked on Page

I am trying to figure this out. Basically the virtual IP 192.168.1.110 will filter port 80 to the real ip address 192.168.20.110. I can confirm this in the logs. When I click any link on the page ...
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1answer
42 views

FTP and WWW services don't acknowledge connections

I have Lubuntu 14.04 LTS with vsftpd and the lamp stack (apache2, etc.) installed. Everything works fine on the LAN. Externally, the services don't acknowledge connection attempts. I can see packets ...
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1answer
56 views

What is the point of a firewall?

Newbie question: I have set up a new Linux server. I have got SSH running on port 22. I have got Apache running on port 80. I am told I should enable a firewall but why is that? 80 and 22 are the ...
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2answers
78 views

DNS servers trying to send data to google+ - google DNS

I was looking through my watchguard traffic today and noticed a lot of traffic going from my two local DNS servers to "Google-Plus". I'm assuming watchguard has that labeled incorrect as the IP ...
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0answers
110 views

Does firewalld handle the common attack rules of iptables by default?

I'm in the process of migrating servers to CentOS 7 from 6.5 and the most major change appears to be the shift from iptables to firewalld. My prior experience with iptables tells me that there are a ...
1
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1answer
124 views

Which incoming port is required by JIRA's outgoing (SMTP) e-mail functionality?

I have a JIRA 6.3.15 installed on an Ubuntu 14.04 in a VirtualBox VM. The host system for VirtualBox also is an Ubuntu 14.04. I configured JIRA to use SSL (as described here ...
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0answers
52 views

What is inserting “/*SC*/” and “/*EC*/” into HTML email comments?

Something is inserting the strings "/*SC*/" and "/*EC*/" into the HTML comments within emails received by our corporate email system: We use MS Exchange at multiple locations, but this is only ...
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votes
1answer
48 views

How to open a mysql port for 2 server connected in LAN

I have 2 servers connected togheter in LAN, and both on external network too. One eth0 and the other eth1 adapter. On both servers I've installed mysql. I'm able from both server to connect to their ...
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1answer
112 views

What is the easiest way to block access from all countries except for one? [closed]

I have a Ubuntu 14.04 server which runs a game server and it's under heavy DDos attack right now. It's not a English-speaking community, so I don't need access from any other countries but mine. All ...
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0answers
41 views

VPN-tunnel renegotiation problems

I have an application running on top of Celery with redis as a broker. Redis is hosted at our datacenter but the workers are hosted on a separate line. We have setup two-way communcation between the ...
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3answers
957 views

How to detect what's blocking my incoming traffic on Ubuntu 14.04 LTS, if it's NOT iptables and NOT EC2 Security Group?

I have SSH root access to an EC2 instance. It's Ubuntu 14.04 LTS. I have nginx web server listening on all interfaces on port 80 TCP. It's accessible from this server but not from the outside. ...
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1answer
63 views

How to list EC2 security group *rules* from within instance?

I have SSH root access to an EC2 instance but no access to the AWS Console / AWS KEY & SECRET. My incoming traffic to this host on all TCP ports except 22 TCP seems to be blocked - I cannot ...
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0answers
37 views

Small Office WiFi config for iPhones

I purchased an ASUS RT-AC66u wireless router for use in a small office. I have the router configured as an access point, DHCP is turned off. It is using a static IP of 10.10.10.251. My DHCP server ...
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0answers
85 views

Cannot access Exchange from guest WiFi

I'm having trouble getting users to be able to connect to Exchange from their cell phones on our wireless. If accessed from completely outside the network, ie from home, then OWA and phone apps sync ...
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2answers
2k views

Can browse, but can't ping

I am behind a corporate network. I am unable to use git, since it can't resolve server names fatal: Unable to look up someserver.org (port 9418) (No such host is known. ) I can't ping that server ...
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0answers
127 views

Extracting Check Point firewall configuration to XML

I need to extract Check Point firewall configuration (roles, management definitions, logs policy and much more) into a readable .XML file. I know that Check Point has a visualization tool, but i ...
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2answers
2k views

Port forwarding to the router itself on Edgerouter

I recently upgraded one of my customers to a Ubiquiti EdgeRouter Lite, which is a significant improvement over their old ISP-supplied router. To reduce the frequency of attacks against the router's ...
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1answer
174 views

libvirt and host firewall

Hiho! I'm using libvirt with kvm and that works great. My desire is to lock down the host system using a host firewall. Up to today I always used shorewall as my iptables mangement utility of choice. ...
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1answer
51 views

connection to ssh server [closed]

How to connect to ssh server on port 22 from behind very restrictive firewall where is only port 80 and 443 available? I tried port mapping on my ssh client but it says it can map local port higher ...
1
vote
1answer
352 views

iptables block port range with single port exception

I`ve two rules. First blocked all port from range: -A INPUT -m state --state NEW -m tcp -p tcp --match multiport --dports 200:65535 -j DROP and second open one in this range: -A INPUT -i ...
1
vote
1answer
51 views

Some Group Policy defined inbound exceptions not showing on local machine

I am turning on the Windows Firewall for the first time for my domain. I am only worrying about workstations for now, and I have defined a list of inbound exceptions. I have these set up using ...
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2answers
244 views

Using iptables or similar to redirect traffic to a proxy

I've searched around for an answer to this question, but it seems like most of what I found wasn't specifically what I wanted to do (mostly redirecting traffic on the same host to squid running on ...
0
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1answer
202 views

Cannot connect to port over the internet (works from localhost)

I'm running something (=Faye server) on port 9292: david@theta:~$ lsof -ni tcp:9292 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME ruby 2406 david 13u IPv4 1579461398 0t0 ...
1
vote
1answer
324 views

Cisco ASA - difference between inside_access_in and inside_access_out?

So a minor problem we have is any internal servers have no (non-icmp) access to the outside is being blocked. Our current config is: inside_access_in any ---> any ---> icmp inside_access_out ...
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1answer
240 views

Rate limit new connections in IPTables instead of Nginx or HAProxy?

I would like to use some form of rate-limiting both 1) new TCP connections and 2) requests over an existing connection to HTTP(S). I will probably handle #2 with nginx or HAProxy (because I have more ...
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0answers
168 views

Rabbitmq windows firewall configuration

I installed rabbitmq on a remote windows server and I opened up port 5672 in the windows firewall settings. I set access to all programs and I was able to connect to rabbitmq. However when I ...
0
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1answer
99 views

Strange TCP Flood / Flood from Port 445

Good Evening. Today I noticed a strange flood on a box that I am working with, here is a dump from tcpdump: 23:21:07.580917 IP (tos 0x0, ttl 64, id 5746, offset 0, flags [DF], proto TCP (6), length ...
0
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0answers
207 views

Route Email to external IP Cisco ASA 5515

I have a cisco ASA 5515X with two WAN connections and one LAN connection. As far as I understand, I hace the firewall configured to allow SMTP traffic through WAN2 interface, but not through WAN1. ...
0
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1answer
44 views

couchdb public access - start failures eaddrnotavail

If I start the couchdb service it fails and with journalctl-xe i can see the following: start request repeated too quickly for couchdb.service And when i do couchdb -i i get the following error: ...
0
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1answer
162 views

Linux firewall, ADSL bonding, two default routes

I am trying to set up a Linux firewall (ubuntu 14.04) to use two bonded ADSL lines for load balancing purposes. I found by searching the forum link to this: ...
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0answers
150 views

nftables, bridge, lxc. Can't call into container

My first post so bear with me. I am using nftables to start to replace old ones. I am loving it, but obviously, my approach is a bit iptables-like and also highly procedural, rather than using the ...
2
votes
1answer
115 views

Docker with a virtualized software firewall ahead

I'm currently working on a Docker setup and here is how I decided to think it : An Ubuntu host, which host : A KVM of an OpenBSD configured and acting as a firewall : The firewall will have it's ...
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0answers
88 views

How do I diagnose a blocked connection to an internet webserver?

When I browse to three specific sites (which happen to be run by the same provider), I get a 403 Forbidden Nginx error. However, the sites are up. I am able to access the sites when I use a proxy ...
1
vote
1answer
224 views

iptables only blocks OpenVPN on server startup

I'm currently in the process of setting up OpenVPN across multiple data centres on Linode. The OpenVPN set up is working great and I'm now focusing on getting my firewall set up so that my public and ...
1
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0answers
151 views

Apache blocking based on combination of ip, request and useragent - Can fail2ban do that?

3 times over the past 48 hours, we had about a 6X spike in traffic lasting a few hours. The server handled it each time, but just barely. This was almost all bad-bot traffic (or maybe failed DOS ...
0
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1answer
126 views

Connection lost to VPS While using iptables by default policy as DROP for INPUT, OUTPUT, FORWARD

I'am using iptables in many server's but now stuck with this issue while using default Policy as DROP. Here is my rules which i have used in VPS, Tried many time's everything seems fine but VPS ...
-1
votes
1answer
70 views

Secure cloud to internal Mail setup using UUCP or something more modern

Some of our Linux servers are going to be moved out into a cloud. But the servers need to be able to email our users internally and are required to use our domain name as sender. The server cannot ...
0
votes
2answers
70 views

Can I prevent some of the UFW messages from being logged?

My router broadcasts (sends to 224.0.0.1) something every forty seconds. This is caught by UFW which stores a log entry in syslog: Jan 5 03:49:02 log kernel: [ 1184.788900] [UFW BLOCK] IN=eth0 ...
1
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1answer
98 views

How do iptables policies work?

I've added some basic rules: iptables -A INPUT -p tcp --dport 22 -j ACCEPT iptables -A INPUT -p tcp --dport 80 -j ACCEPT Then, command to close all other ports with: iptables -A INPUT -j DROP ...
2
votes
0answers
105 views

firewall-cmd forward rules for interface with multiple ips

I'm looking for a way with firewall-cmd or another command to do the following. An incoming public interface has multiple ip addresses bound to it. How can I forward ports only for one of the ip ...
3
votes
1answer
2k views

Windows Server 2012 Port Forward for Specifc Host

I am trying to have a specific host be redirected to another port when trying to access a service on port 80. So, when the client (192.168.1.22) requests a connection to the server (192.168.1.10) on ...
2
votes
1answer
80 views

PF redirect rule: how to limit the rule to specific user

I was trying to setup a PF redirect rule to force all web traffic from a specific user account to go through a web filter on a shared computer. With iptables, I can use --uid-owner option to limit ...
-2
votes
1answer
62 views

Opinions about firewall rules for vps [closed]

I just switched to a new vps, which I installed Linux and I wish to harden it a bit by applying firewall rules using iptables. I use Firewall Builder to create my rules and I would like some ...