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

learn more… | top users | synonyms

0
votes
1answer
13 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?
0
votes
0answers
6 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 ...
-4
votes
2answers
32 views

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 have already disabled root login via SSH, turned off password authentication, and implemented SSH keys. I wanna go one step further and only allow SSH connections to originate from within our ...
0
votes
0answers
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 ...
0
votes
1answer
12 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 ...
2
votes
0answers
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 ...
1
vote
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 ...
-3
votes
0answers
13 views

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

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 ...
1
vote
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 ...
2
votes
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. ...
0
votes
0answers
18 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 ...
-1
votes
1answer
24 views

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 ...
2
votes
1answer
42 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 ...
0
votes
1answer
14 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 ...
0
votes
0answers
15 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 ...
0
votes
1answer
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 ...
0
votes
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 ...
1
vote
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 ...
0
votes
0answers
25 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 ...
0
votes
2answers
31 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 ...
0
votes
0answers
6 views

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 ...
15
votes
2answers
2k views

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 ...
2
votes
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 ...
0
votes
1answer
49 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 ...
0
votes
1answer
32 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 ...
2
votes
0answers
37 views

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 ...
-1
votes
1answer
50 views

What's blocking the PCI compliance scanner from scanning my site? [closed]

(I am not sure if this question fits in serverfault.com. If not, forgive me.) I maintain my client's ecommerce website and the credit card processing company requires PCI compliance. For that, our ...
1
vote
1answer
18 views

Does order of UFW rules matter?

When I first initialized my ufw, I did ufw default allow outgoing ufw default deny incoming ufw allow 80/tcp ufw allow 22/tcp Over the last week or so, I've been going through my access logs and ...
0
votes
2answers
38 views

Can I access a NAT addressed host behind a gateway from the WAN side without DNS or VPN (with DNS if it's not possible)?

I have a very simple gateway running a minimal Linux which is serving as an IP router with NAT and DHCP on the LAN, and a static IP on the WAN. The gateway router from the LAN side goes to a big ...
0
votes
0answers
27 views

Want to Ping/access my Public Ip from Private IP, NAT firewall

One of my server is having private IP x.x.x.x and the Public IP for that server is 1.1.1.1 now when i try to Ping my Public IP from same server its not working, Firewall is NAT enabled. I want to ...
0
votes
0answers
46 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 ...
0
votes
0answers
31 views

Cisco ASA 5505 Split Tunnel Multiple Networks Not Working

I have an ASA 5505 and cannot get Internet access for VPN users. Config Layout is specified below. ASA (10.15.0.1)-->(10.15.0.2) Core Switch (10.5.1.0) Below is my config. ...
-1
votes
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 ...
0
votes
0answers
18 views

MSSQL Server 2008 - Allow One Outside IP with Windows Firewall

We have a MSSQL Server that has localhost connections, but need to have one connection to another machine. The other machine needs to login to MSSQL server. We added an Inbound Windows Firewall rule ...
3
votes
0answers
17 views

RANCID - timeout connecting PALOALTO in HA

When rancid try to connect via SSH to PALO (the active one) i get a time out message. Connecting manually everything is ok. I believe is something related to prompt containing parethesis. add user ...
1
vote
0answers
15 views

Is it possible to reverse ssh to a system behind a router via a third system if port forwarding is disabled on the middle system?

I want to access a workstation in my lab from my laptop in my hostel room. But I can't directly ssh to the machine as both my laptop (in my hostel) and the worstation are behind two different routers ...
1
vote
1answer
43 views

Vyatta and DNS Rewrite (aka hairpin or doctoring)

I'm trying to make my public IP reachable also from inside LAN. I know that it's better to spilt DNS in order to have an internal zone that solves hosts with internal IP, but for a lot of reasons ...
1
vote
2answers
28 views

connect to server in seperated lan (using openwrt)

I am using openwrt with the following setup: --------------- | |--- LAN1 192.168.1.1/24 WAN 194.X.X.X ---| openwrt-box | ...
0
votes
0answers
20 views

ICMP packets in firewalld zones

How are the zones in firewalld configured w.r.t ICMP packets? and do they act differently for interfaces and sources? 1. How firewalld route ICMP packets? I would assume the main zones act as they ...
0
votes
1answer
12 views

Opening a port to access a service in an isolated LAN

There is an isolated LAN (completely isolated, does not access outside and outside can't access it). But one of the server has 2 NICs, one of which is on our dev LAN and the other one in the isolated ...
0
votes
0answers
11 views

Windows firewall profile for USB Ethernet

I am using Windows 7 and on my notebook I have an ethernet port which is connected to the companys network. I connected a USB Ethernet to connect other devices through a static IP. I wanted to block ...
0
votes
2answers
33 views

Simplest way to secure debian server on LAN

I currently have a basic debian server setup and connected to my LAN. Am I right in thinking that if I remove the gateway from the network configuration then the box will be unable to communicate ...
0
votes
0answers
15 views

local port forwarding with failover

There is a number of similar though not identical processes (worker processes) running on the localhost and listening each on its own TCP port, let's say process1 is listening on port 10001 process2 ...
1
vote
1answer
38 views

Port forward linux iptables

My current network setup consists of a physical nic eth1 receiving my public ip from the modem. Next I have kvm/qemu virtual machines running on a virtual network using the ip range 192.168.122.0 - ...
0
votes
0answers
12 views

use of secondary public IP subnet in Sonicwall NSA firewalls

I have a Sonicwall NSA 3500/4500 firewall. I have a primary block of public IP addresses that are working fine but I need to utilize a second block of IPs that are routing over the primary from the ...
2
votes
1answer
56 views

Securing Windows Server 2012 from the internet

I've placed my direct internet connection into the public profile for the firewall and started disabling every rule to block all but RDP. The only rules I am not sure about are these Core Networking ...
1
vote
0answers
21 views

Running a Windows Server connected to the internet [closed]

I've been running Linux servers online for years so I know security very well for *NIX. However, I recently setup a Windows Server Network at home and decided I wanted to connect one of my Windows ...
0
votes
0answers
9 views

Route some rule on App Rules to second wan on Dell Sonicwall TZ215

Im using Dell sonicwall TZ215 with firmwire SonicOS Enhanced 5.9.0.4-127o and have 2 wan connection. The question is, is it possible to route some rule on App rules to second wan? I'm already try ...
0
votes
0answers
14 views

Opening up the firewall to Google Cloud Messaging

I'm trying analyse the firewall requirements for push notifications on iOS and Android devices. It's relatively simple for iOS: they need the entire 17.0.0.0/8 address block to ensure APNs runs ...
0
votes
1answer
57 views

How to create advanced rules with firewall-cmd?

I want to create a rule using firewalld that uses criteria username or userID and maybe one other module criteria. In iptables, I think you can do things like iptables -A OUTPUT -m owner --uid-owner ...