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

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Iptables linux routing with 2 chain proxies

Im trying to setup a connection between a PCs in my local network, to foreign resource XYZ in a specific way. My network is currently configured like this: I have a pc behind the proxies -> Then I ...
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42 views

Not able to RDP to the VM which is part of new subnet in Azure virtual network

Here are my environment detail I am using Azure IaaS (Infrastructure as Service) I am having one vNet (Virtual Network) I have set-up site to site connectivity (on-premise to azure) I have one subnet ...
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2answers
12k views

tcp syn checking

I have a WatchGuard Firebox that I've recently configured. All of the policies look fine and all appropriate services seem to be working correctly. However, one or two (seemingly) random nodes keep ...
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1answer
213 views

OpenVPN Ubuntu Server Routing Problems No Internet

I'm running OpenVPN on Ubuntu 15.04. When I connect to the server, I can connect and authenticate correctly (I use PAM auth because I'm lazy). Once connected I can't ping the server or access the ...
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16 views

CSF Firewall unblock countries

I've a VPS Server running CENTOS 6.7 x86_64 with CSF Firewall activated. Sometimes I see in "Firewall Deny IPs" that blocks suddenly connections from my country (Spain) to some of my clients. Not ...
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3answers
39 views

UFW: How to block http requests on another port than 80?

I am running an application on port 7000 which is part of a network. So it has to communicate over port 7000 with all other servers of the network (not LAN, dynamic IPs). It has also a web frontend ...
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1answer
48 views

How can I block access to the internet for static addresses?

I have a router on CentOS 7 which provides access to internet for several IP addresses, which are reserved at DHCP server. Other hosts are blocked. If someone put static address from the reservation ...
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0answers
30 views

Sizing Firewall for Micro-Datacenter

We have a small data center we're finishing. We have a core+spline and then redundant TOR switches. Everything is basically whitebox 10gb switches running Cumulus; although, we will upgrade the core ...
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1answer
111 views

CentOS port forward

I have the following situation: Internet ----- Server ------- virtual machine (kvm) public ip 192.168.122.12 x.x.x.x I need to make service on the port 3333 ...
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77 views

ssh login timed out after enabling the ufw firewall ubuntu server

I followed digital ocean tutorial to enable the firewall in my ubuntu server. The steps I performed is: 1> change the port no to some other no. (8338) 2> enable firewall using sudo ufw allow ...
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4answers
22k views

What host names and ports would need to be opened in a firewall to allow Windows Updates to work?

We have a set of public web servers behind a firewall we would like to be able to perform Windows Updates on, without giving them more access than they need. Besides www.update.microsoft.com:443, ...
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3answers
17k views

Centos iptables open port 53

I am having problem opening port 53 on my centos machine, for DNS configuration. Here is my iptables config -A INPUT -p udp -m udp --sport 53 -j ACCEPT -A OUTPUT -p udp -m udp --dport 53 -j ACCEPT ...
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85 views

IPset Alternatives and Firewall Management

I have CentOS 7, Plesk 12, 8GB RAM VPS. I have around 1000 rules in my IPtables to block abusive users. But when reloading IPtables it takes 15 seconds to reload all 1000 rules. First of all, is it ...
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23 views

Self signed Cisco VPN Certificate

So I just rented some servers protected with a Cisco Firewall from a data center provider. I plan on accessing these servers through VPN. The instructions from the data center provider was to ...
6
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5answers
177 views

Adding second firewall to ISP connection with multiple subnets?

My routing knowledge is a little rusty. I have a fibre internet connection hooked up like this: The managed switch breaks out VLANS for transparent lan service that is also through the ISP's box. ...
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1answer
1k views

Set adapter to use Windows Firewall Public Profile

I'm configuring a server to provide VPN access to employees on the road. This server is virtualized, which means that both the Internal and the External network adapters, are actually connections to ...
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1answer
45 views

Centos 7 network issue

I have a Centos 7 server behind a Dell sonicwall I have configured the sonicwall to allow certain services and this seems to work fine. However I can't telnet to some ports. I have added Wireshark to ...
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0answers
106 views

ASA INSIDE to INSIDE traffic being dropped

An ASA 5505 is being used to route between two networks as it contains routes to everything. The following depicts the network topology. I have tried various combinations of access lists such as: ...
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2answers
142 views

How to open firewall to access azure file storage

We are going to use robocopy to keep a stack of encrypted files synced to an azure file share. But what do we need to open on the firewall to let the backup server get to an azure storage file share? ...
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1answer
35 views

ZyWall USG 50 locked out

A Friend of mine was testing something in our Server Room. He made a firewall Rule on the Zywalls' web-interface like this: Block All from All to Zywall So, now we cant access the Webpannel anymore (...
3
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0answers
150 views

Hacker bypassing iptables

(moved from SO) I have iptables protecting a sip server. It blocks all IPs except ones I specifically opened, and it seems to work for almost everyone. I have tested from lots of ip addresses that ...
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1answer
1k views

“Could not generate DH key pair on the destination URL” error

What could cause a Could not generate DH key pair on the destination URL error? A EDI partner company tries to connect to our HTTPS server and encounters the above message. Or system uses a ...
2
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1answer
38 views

IPTables Configuration to allow all connections, only close/deny once data is sent

I'm looking to set up my IPTables firewall in such a way that: Any new connect() is accepted Once data is received: If the destination port is on a whitelist, continue allowing the connection and ...
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1answer
33 views

Why is lfd prematurely removing blocks?

As you can see in the excerpted log file below (from /var/log/lfd.log), lfd is prematurely removing temporary blocks that it imposes on IPs: Apr 7 13:07:59 host lfd[32117]: (wordpressxmlrpc) Request ...
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2answers
1k views

Running multiple services on one Port 443 is possible?

I am new to network and firewall things, In our 2008 R2 server i have configured WCF service on windows service with port 443 and later i found another windows service already using the same port ...
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66 views

Traffic on eth0 despite denying it with iptables

Despite having an iptables ruleset which should not allow it - DHCP is working on eth0. Given the below information can anyone give me an idea of why? tap0 is not up (not that it should make any ...
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59 views

PFsense 2.2.6 static dhcp hostname blank

We are on pfsense 2.2.6 and we enable static dhcp for each mac address on each VLAN where dhcp is enable. DHCP is working good but when I enable static dhcp and leave the hostname empty and when I ...
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1answer
10k views

How to set up port forwarding on a NETGEAR ProSafe™ Gigabit 8 Port VPN Firewall FVS318N?

UPDATE: Rule might be right, but app still isn't functional. See more details after the screenshots. I want to forward port 3000 to a machine in the local network (192.168.1.106). So far I've ...
3
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1answer
98 views

Reject all except for whitelist policy with firewalld

I've been reading on firewalld for about the whole morning, and I came up with the following public zone: <?xml version="1.0" encoding="utf-8"?> <zone> <short>Public</short> ...
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0answers
29 views

firewalld multiple public ips to multiple private ips routing

I'm trying to use CentOS 7 server as a firewall/nat for some sensitive servers on the LAN. The CentOS server has multiple public IPs (one per box on the LAN) and I'm trying to associate each external ...
61
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3answers
432k views

How to check if a port is blocked on a Windows machine?

On the Windows platform, what native options to I have to check if a port (3306, for example) on my local machine (as in localhost), is being blocked?
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1answer
2k views

What do I need to consider when setting TCP idle timeouts?

What's purpose of having a [low] TCP idle timeouts? E.g., why have a 60 second timeout on a firewall or load-balancer? Is it a memory management or /performance optimization thing? Is there a security ...
3
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1answer
27 views

Will it detriment my security if I allow all connections from localhost through iptables?

Under my current configuration, iptables will block every inbound connection, even if coming from localhost. In some cases, I need localhost to connect to itself. If I create a rule that allows all ...
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1answer
24 views

Failed to open a port in my ubuntu machine [duplicate]

Recently I added to iptables a rule which was supposed to allow incoming traffic through port 993. The rule I used is the one shown below: sudo iptables -A INPUT -p tcp --dport 993 -j ACCEPT After ...
6
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1answer
25k views

Openvpn routing for lan to lan through tun

I am trying to setup an OpenVPN tun to connect two lan's The open vpn connection is up and working but there is a problem with my routing or nat or something. What I need is an example of what a ...
0
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1answer
43 views

Why is TTL increasing? (and generally behaving erratically)

Summary: TTL is not decremented when pinging hosts on a "network path" My laptop (10.10.13.10) is connected via OpenVPN to a server (10.10.13.1) which hosts several network interfaces. One of them is ...
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1answer
31 views

Strange Firewall Placement? [closed]

I joint a company recently and manager given me a network design. I found that the network design is a bit different than normal cases. As I'm newbie on firewall. Does the below setting proper? They ...
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3answers
10k 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
71 views

Firewall configured to allow 25/tcp but still cannot telnet into server on that port [duplicate]

I've got postfix and dovecot running on ports 25, 110, 587, 465, 993, 995 for the usual mail protocols. I can telnet into all ports except port 25 which you can see below. Any ideas on what's going on?...
2
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1answer
58 views

Only allow access to a port when connected to VPN

I am running a Centos 7 server with OpenVpn on an amazon ec2 server. How can I configure it to only allow access to ports 2087 and 2083 when I am connected to the VPN, but not when I am not connected. ...
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0answers
21 views

WCCP to Remote Cache Engine - Any limitations?

I am attempting to WCCP to a remote (cloud hosted) cache engine from an ASR 1900 series router that is performing NAT. According to my reading (which was mostly done on ASAs) the WCCP cache engine ...
2
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0answers
30 views

Allowing outbound internet access with NSX while maintaining micro segmentation

I am getting into the world of VMware's NSX product for the purpose of micro segmenting VM's in the datacenter. That is to say, living in the same network space but not being able to talk to one ...
0
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1answer
28 views

Reverse ssh for location distributed system behind firewall

We have multiple machines located in different area behind firewall which don't have Static IP and can't be accessible from the outside. We would like to access those machines but are wondering what ...
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1answer
113 views

Separate subnet with exceptions [closed]

I have a network with clients in the 192.168.30.x range and clients in the 192.168.40.x range. both are in a 255.255.0.0 subnet. All clients with .30.x are connected to one switch and all clients with ...
8
votes
3answers
10k views

Why can't I ssh or ping my brand new Amazon EC2 instance?

I just created a free EC2 instance with all the defaults. It says it's running in the AWS Management Console. On the "Instance Actions" menu, I click "Connect". I copy the DNS name provided (looks ...
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1answer
12 views

Granular Windows firewall rule control

Is there a way using group policy (or some other built in mechanism) to apply firewall rules in such a way that a subset of the rules are locked and cannot be changed or overridden, but another subset ...
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114 views

FirewallD is not running in CentOS Linux 7.1.1503

I wanted to add a port 5004 for tcp connection. So I run the command: firewall-cmd --permanent --add-port=5004/tcp However I got an error: FirewallD is not running So by some research, I run the ...
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0answers
615 views

Nginx proxy_pass reverse proxying behind corporate firewall

Has anyone any idea of how to setup nginx behind a corporate firewall, to reverse proxy requests to servers outside the firewall? The reason I want to do this is I am trying to use an application ...
2
votes
1answer
63 views

Opensuse 13.2 firewall: allow openmpi

I am trying to run simple openmpi test on two servers. mpirun --report-bindings --host serv1.cell,serv2.cell -np 2 hostname Both servers runs OpenSuse 13.2 and have similar network inteface ...
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0answers
12 views

Set up trust on the external forest from the external forest

At one point in the document linked below it says "Set up trust on the external forest from the external forest" Inbound ports :N/A Outbound ports :LDAP (389 UDP and TCP)Microsoft SMB (445 TCP)...