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• How to change Port 27000 from filtered to open status

  - by Nadarajah Ranjan

  In my ubuntu box I am running flexlm licensing software on port 27000 and I am able to pull the license from the this port to run the simulation software locally. I am also trying to run the same software in another Linux machine (opensuse) by using the flexlm license from the Ubuntu box. However, my opensuse box is unable to communicate with port 27000 in my Ubuntu box. I have turned off the firewall on the Ubuntu box, played around with iptables and when I do a nmap from my opensuse box to Ubuntu box the message I get is that port 27000 is on filtered status. My understanding is that filtered status does not allow the opensuse box to communicate with Ubuntu. My question is how to change port 27000 from filtered status to open status? Hope someone can help me out. Thank you.

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• keep getting added to hosts.deny + iptables

  - by Sc0rian

  I am confused to why this has started to happen. On my local network, if I click 10-20 apache/http links my server will decide to add me hosts.deny file and block me on iptables. Its not just apache, it seems to happen with any kinda of traffic, that comes in on a flood method. Like I use subsonic, if I change tracks 10-20 times, it will do it. I would assume I have some sort of firewall which is sitting on the server which is doing this. However I do not have fail2ban or any denyhosts in /var/lib. I cannot work out why I keep getting added to hosts.deny/iptables. Thanks

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• Chinese SEO - Scaling the Great Firewall

  At approximately 1.3 billion, it has the largest population in the world. The number of its Internet users rises significantly each year. It has a great virtual wall that rivals its real one that stretches 8,800 kilometers from Shanhaiguan to Lop Nur. It is the People's Republic of China (PRC).

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• Oracle Buys Database Firewall Firm Secerno

  Oracle's latest purchase will provide additional protection from internal and external threats to enterprises' Oracle and non-Oracle databases.

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• Introducing Next-Generation Enterprise Auditing and Database Firewall Platform Webcast, 12/12/12

  - by Troy Kitch

  Join us, December 12 at 10am PT/1pm ET, to hear about a new Oracle product that monitors Oracle and non-Oracle database traffic, detects unauthorized activity including SQL injection attacks, and blocks internal and external threats from reaching the database. In addition, this new product collects and consolidates audit data from databases, operating systems, directories, and any custom template-defined source into a centralized, secure warehouse. This new enterprise security monitoring and auditing platform allows organizations to quickly detect and respond to threats with powerful real-time policy analysis, alerting and reporting capabilities. Based on proven SQL grammar analysis that ensures accuracy, performance, and scalability, organizations can deploy with confidence in any mode. You will also hear how organizations such as TransUnion Interactive and SquareTwo Financial rely on Oracle today to monitor and secure their Oracle and non-Oracle database environments. Register for the webcast here.

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• iptables firewall to protect against automated entries

  - by Kenyana

  I am getting unusually large calls on my app. I have implemented CSRF Check over ajax and its working but am still getting so many calls. My guess is that someone has a script that is 'logged' in and making all these calls. Could someone please share a good iptables script for blocking ip's that run 10 calls to /controler/action in a second. I am using `/sbin/iptables -A INPUT -p tcp --syn --dport $port -m connlimit --connlimit-above N -j REJECT --reject-with tcp-reset save the changes see iptables-save man page, the following is redhat and friends specific command service iptables save` That is from cyberciti

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• Oracle Grabs Secerno for Database Firewall

  The move comes amid increasing industry interest in database monitoring and security solutions.

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• Different routing rules for a particular user using firewall mark and ip rule

  - by Paul Crowley

  Running Ubuntu 12.10 on amd64. I'm trying to set up different routing rules for a particular user. I understand that the right way to do this is to create a firewall rule that marks the packets for that user, and add a routing rule for that mark. Just to get testing going, I've added a rule that discards all packets as unreachable: # ip rule 0: from all lookup local 32765: from all fwmark 0x1 unreachable 32766: from all lookup main 32767: from all lookup default With this rule in place and all firewall chains in all tables empty and policy ACCEPT, I can still ping remote hosts just fine as any user. If I then add a rule to mark all packets and try to ping Google, it fails as expected # iptables -t mangle -F OUTPUT # iptables -t mangle -A OUTPUT -j MARK --set-mark 0x01 # ping www.google.com ping: unknown host www.google.com If I restrict this rule to the VPN user, it seems to have no effect. # iptables -t mangle -F OUTPUT # iptables -t mangle -A OUTPUT -j MARK --set-mark 0x01 -m owner --uid-owner vpn # sudo -u vpn ping www.google.com PING www.google.com (173.194.78.103) 56(84) bytes of data. 64 bytes from wg-in-f103.1e100.net (173.194.78.103): icmp_req=1 ttl=50 time=36.6 ms But it appears that the mark is being set, because if I add a rule to drop these packets in the firewall, it works: # iptables -t mangle -A OUTPUT -j DROP -m mark --mark 0x01 # sudo -u vpn ping www.google.com ping: unknown host www.google.com What am I missing? Thanks!

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• MSDTC - Communication with the underlying transaction manager has failed (Firewall open, MSDTC network access on)

  - by SocialAddict

  I'm having problems with my ASP.NET web forms system. It worked on our test server but now we are putting it live one of the servers is within a DMZ and the SQL server is outside of that (on our network still though - although a different subnet) I have open up the firewall completely between these two boxes to see if that was the issue and it still gives the error message "Communication with the underlying transaction manager has failed" whenever we try and use the "TransactionScope". We can access the data for retrieval it's just transactions that break it. We have also used msdtc ping to test the connection and with the amendments on the firewall that pings successfully, but the same error occurs! How do i resolve this error? Any help would be great as we have a system to go live today. Panic :) Edit: I have created a more straightforward test page with a transaction as below and this works fine. Could a nested transaction cause this kind of error and if so why would this only cause an issue when using a live box in a dmz with a firewall? AuditRepository auditRepository = new AuditRepository(); try { using (TransactionScope scope = new TransactionScope()) { auditRepository.Add(DateTime.Now, 1, "TEST-TRANSACTIONS#1", 1); auditRepository.Save(); auditRepository.Add(DateTime.Now, 1, "TEST-TRANSACTIONS#2", 1); auditRepository.Save(); scope.Complete(); } } catch (Exception ex) { Response.Write("Test Error For Transaction: " + ex.Message + "<br />" + ex.StackTrace); }

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• VPN pptp connection Unable to pass through linux iptables

  - by user221844

  I have set up a windows VPN server behind Linux - Ubuntu box that is working as firewall and proxy server. Now I want people from outside to be able to connect to the VPN server, but the connection is not being established and I get on the client an error 619. I have checked the problem on the internet and it seems a firewall issue. what should I do to make the connection established through the firewall? here is below the information about my setup Firewall-External-IF-IP: 172.16.1.100 Firewall-LAN-IF-IP: 192.168.1.1 VPN-Server-IP: 192.168.1.10 and below is my iptables file content: #Generated by iptables-save v1.4.12 on Thu May 29 12:40:18 2014 *filter :INPUT ACCEPT [162000:140437619] :FORWARD ACCEPT [23282:27196133] :OUTPUT ACCEPT [185778:143961739] :LOGGING - [0:0] -A INPUT -p gre -j ACCEPT -A INPUT -s 192.168.1.10/32 -p tcp -m tcp --sport 1723 -j ACCEPT -A INPUT -s 192.168.1.10/32 -p udp -m udp --sport 1723 -j ACCEPT -A FORWARD -s 192.168.1.0/24 -o EXT_IF -j ACCEPT -A FORWARD -s 192.168.1.0/24 -i EXT_IF -m state --state RELATED,ESTABLISHED -j ACCEPT -A FORWARD -d 192.168.1.10/32 -i EXT_IF -o INT_IF -p tcp -m tcp --dport 1723 -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT -A FORWARD -s 192.168.1.10/32 -i INT_IF -o EXT_IF -p tcp -m tcp --sport 1723 -m state --state RELATED,ESTABLISHED -j ACCEPT -A FORWARD -d 192.168.1.10/32 -i EXT_IF -o INT_IF -p gre -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT -A FORWARD -s 192.168.1.10/32 -i INT_IF -o EXT_IF -p gre -m state --state RELATED,ESTABLISHED -j ACCEPT -A OUTPUT -p gre -j ACCEPT -A OUTPUT -d 192.168.1.10/32 -p tcp -m tcp --dport 1723 -j ACCEPT -A OUTPUT -d 192.168.1.10/32 -p udp -m udp --dport 1723 -j ACCEPT COMMIT # Completed on Thu May 29 12:40:18 2014 # Generated by iptables-save v1.4.12 on Thu May 29 12:40:18 2014 *nat :PREROUTING ACCEPT [17865:1053739] :INPUT ACCEPT [5490:357281] :OUTPUT ACCEPT [3723:223677] :POSTROUTING ACCEPT [3726:223870] -A PREROUTING -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 3128 -A PREROUTING -d 172.16.1.100/32 -i EXT_IF -p tcp -m tcp --dport 1723 -j DNAT --to-destination 192.168.1.10 -A PREROUTING -d 172.16.1.100/32 -i EXT_IF -p gre -j DNAT --to-destination 192.168.1.10 -A PREROUTING -i -h -A POSTROUTING -s 192.168.1.0/24 -o EXT_IF -j MASQUERADE COMMIT # Completed on Thu May 29 12:40:18 2014 # Generated by iptables-save v1.4.12 on Thu May 29 12:40:18 2014 *mangle :PREROUTING ACCEPT [22695965:17811993005] :INPUT ACCEPT [13818180:11522330171] :PREROUTING ACCEPT [17865:1053739] :INPUT ACCEPT [5490:357281] :OUTPUT ACCEPT [3723:223677] :POSTROUTING ACCEPT [3726:223870] -A PREROUTING -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 3128 -A PREROUTING -d 172.16.1.100/32 -i EXT_IF -p tcp -m tcp --dport 1723 -j DNAT --to-destination 192.168.1.10 -A PREROUTING -d 172.16.1.100/32 -i EXT_IF -p gre -j DNAT --to-destination 192.168.1.10 -A PREROUTING -i -h -A POSTROUTING -s 192.168.1.0/24 -o EXT_IF -j MASQUERADE COMMIT # Completed on Thu May 29 12:40:18 2014 # Generated by iptables-save v1.4.12 on Thu May 29 12:40:18 2014 *mangle :PREROUTING ACCEPT [22695965:17811993005] :INPUT ACCEPT [13818180:11522330171] :FORWARD ACCEPT [8527694:6271564562] :OUTPUT ACCEPT [14748508:11899678536] :POSTROUTING ACCEPT [23271280:18170828012] COMMIT # Completed on Thu May 29 12:40:18 2014 hope that I find the solution here ....!! :(

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• how does teamviewer find my computer even if my comp. behind of the firewall and firewall isn't conf

  - by uzay95

  Did you use teamviewer? (comic question i know... Who doesn't use it?) Do you have any idea how does teamviewer make connection even if i am behind the router, firewall, switch and my local firewall..? I'm trying to imagine a connection that is between remote machinge and my computer. Remote machine is sending the packets (and its header (for instance, destination IP, message body)) to me but it only knows my id number(which is given by my local teamviewer application). And this packets are reaching to my computer even if there is a juniper firewall (and also my windows firewall). What kind a message body is recieving by computer? (of course it is not like xml, text, html, excel :) Do you have any idea? PS. Please share your knowledge like you are explaining to beginner level user.

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• iTunes Home Sharing only works one way between 2 WinXP PC's on the same LAN

  - by scunliffe

  Both PC's have the latest iTunes installed. PC (A) can "see" that there is a shared library "B library" but attempts to connect to it return this error message: The shared library "{Username}'s Library" is not responding (-3259) Check that any firewall software running on either the shared computer or this computer has been set to allow communication on port 3689. however the reverse works fine. e.g. PC (B) can "see" shared library "A library" and can access all content. Notes: Both PC's have Home Sharing enabled (turned off/on several times to verify). Both PC's have Windows Firewall turned on, but in the exceptions tab, iTunes is allowed, and Port 3689 is also added as a firewall exception (just in case) Both iTunes accounts have been "authorized" on both PC's Both PC's connect via LAN via D-Link DIR-615 router. In the advanced application rules, iTunes has also been added to allow traffic on port 3689 un-hindered. Is there any other magical setting/configuration option that I should be aware of and set in order to get this to work? I could care less about sharing apps etc. I just want the music sharing to work. Update: Solved! It turns out on PC (B) there were multiple accounts set up. 1 of the accounts had the checkbox checked under the windows firewall "On" option which states "No exceptions" thus even though it was added to the exception list on the main user account, this other account was blocking access.

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• SQL Server 2008 Remote Access

  - by Timothy Strimple

  I'm having problems connecting to my SQL Server 2008 database from my computer. I have enabled remote connections as described in this answer (http://serverfault.com/questions/7798/how-to-enable-remote-connections-for-sql-server-2008). And I have added the ports listed on the microsoft support page to our Cisco Asa firewall and I'm still unable to connect. The error I'm getting from the SQL Management Studio is: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.) (Microsoft SQL Server, Error: 10060) Once again, I have double and triple checked that remote connections are enabled under the database properties and that TCP is enabled on the configuration page. I've added tcp ports 135, 1433, 1434, 2382, 2383, and 4022 as well as udp 1434 to the firewall. I've also checked to make sure that 1433 is the static port that is set in the tcp section of the database server configuration. The ports should be configured correctly in the firewall since http/https and rdp are all working and the sql server ports are setup the same way. What am I missing here? Any help you could offer would be greatly appreciated. Edit: I can connect to the server via TCP on the internal network. The servers are colocated in a datacenter and I can connect from my production box to my development box and vice versa. To me that indicates a firewall issue, but I've no idea what else to open. I've even tried allowing all tcp ports to that server without success.

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• New router messed up server 2003 setup...

  - by Aceth

  Hey, We were sent a new 2wire router today configured it as best we can to match the old bt voyager. We've also got X static IP's. We've manage to get our webserver on one of the new IP's public facing. then we use a hardware firewall which is in a DMZ again with a different static IP. This firewall then is our gateway for our internal LAN. with a few servers etc. The problem we're having is only our PDC (primary Domain controller which has exchange 2003 on) can't ping externally even an external IP. We've connected laptops to the 2wire router and obtain a private ip 192.168.1.X and it works fine can ping etc. our other servers with an internal ip behind the firewall can ping out fine. We've connected to the firewalls logging console and the pings from the server are allowed through so its fine there. The server in question is a Windows server 2003 R2 Enterprise SP2 + Exchange 2003 Server doesn't have firewall turned on. it has static private IP .. gateway is pointing to the right one External Static IP is routing fine inwards We've ran out of ideas .. help??

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• Routing for Two Hosts Behind a IPSec Tunnel

  - by Brent

  Network A 10.110.15.0/24 Firewall is .1 Host A is .2 Network B 10.110.16.0/24 Firewall is .1 Host B is .2 Two Cisco ASA's. IPSec tunnel with a crypo map that secures 10.110.15.0/24 <- 10.110.16.0/24. Let's say two hosts, 10.110.15.2 and 10.110.16.2 need to talk to each other. Normally I have to enter a persistent static route on a each host along the lines of: route add 10.110.16.0 mask 255.255.255.0 10.110.15.1 metric 1 -p (on the "A" box) I also have to enter another persistent static route on the .16 host in order for the traffic to know how to get back to the .15 network. Note that the default for each machine IS the firewall, so .1. I have no problem adding persistent routes on Windows/ESX/*nux machines but what about a smart switch in the .16 network that I want to manage from the .15 network. Do I need to run a routing protocol? Do I need to have Reverse Route Injection enabled on both ends of the IPSec tunnel? Should I add a route on the firewall? If so, how do you formulate it? Does it get a metric of 1 and my default route 0.0.0.0 get a metric of 2?

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• pfsense, active directory, local domain

  - by Dalton Conley

  First things first, I have no idea what I'm doing. Certainly not afraid to admit that.. but here is my network setup. I have 2 servers, one of them in a domain controller. Both are running windows server 2008. They have replicated directories. Each server is at a different location and has its own firewall for the network at that location. Both firewalls are using pfsense. Recently a firewall went down and my coworker reinstalled pfsense, and everything seems setup correctly. Again, I have no idea what I'm doing so I'm not sure. I have records from when the previous IT person had setup this network and the firewall settings are the same but those records could have been extremely old. Now, I have a domain name for my network.. we'll call it "mydomain.net". I use to be able to access this domain name and it would bring up the servers replicated drives(i.e. \\mydomain.net). Now I cannot. I can however access the servers individual host names on my network(i.e. \\server1 , \\server2). We didn't change anything on the server which is what makes me think its something to do with the firewall. I know this is probably a very general question and I don't have a lot of detail to add but could anyone give me some insight on to what could be causing this, or some debugging techniques I can apply to this? I'm a programmer, not a network administrator.

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• Isolate clients on same subnet?

  - by stefan.at.wpf

  Given n (e.g. 200) clients in a /24 subnet and the following network structure: client 1 \ . \ . switch -- firewall . / client n / (in words: all clients connected to one switch and the switch connected to the firewall) Now by default, e.g. client 1 and client n can communicate directly using the switch, without any packets ever arriving the firewall. Therefore none of those packets could be filtered. However I would like to filter the packets between the clients, therefore I want to disallow any direct communication between the clients. I know this is possible using vlans, but then - according to my understanding - I would have to put all clients in their own network. However I don't even have that much IP addresses: I have about 200 clients, only a /24 subnet and all clients shall have public ip addresses, therefore I can't just create a private network for each of them (well, maybe using some NAT, but I'd like to avoid that). So, is there any way to tell the switch: Forward all packets to the firewall, don't allow direct communication between clients? Thanks for any hint!

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• Single m0n0wall - Two LAN Subnets - How To Setup

  - by SnAzBaZ

  I have two LAN subnets that I need to link together they are 192.168.4.0/24 and 192.168.5.0/24 There is a m0n0wall running on 192.168.4.1. It's LAN connection goes out to our network switch, and it's WAN port goes out to our ADSL modem. WAN is connected via PPPoE. The 192.168.4.0 subnet contains all of our office workstations. The 192.168.5.0 subnet contains development servers and test machines that need to obtain internet access and be "managed" by computers on the 192.168.4.0 subnet, but need to be on their own subnet as well. I have a Draytek 2820N configured on 192.168.5.1 with it's WAN2 port configured as 192.168.4.25 and a default gateway of 192.168.4.1. Machines on the 5.0 subnet can connect to the internet via the m0n0wall just fine. I configured a static route on the m0n0wall LAN interface, Network 192.168.5.0/24 and Gateway 192.168.4.25. Machines on the 5.0 subnet can ping machines on the 4.0 network but the reverse does not work. I configured a new firewall rule on the m0n0wall that allows any traffic on the LAN interface with a source IP of 192.168.4.25 to be allowed. The DrayTek firewall is currently configured to pass all traffic regardless. When I try to ping a machine in the 5.0 subnet from 4.0 I see this in my m0n0wall log: BLOCK 14:45:27.888157 LAN 192.168.4.25 192.168.4.37, type echoreply/0 ICMP So the reply is being sent from the 5.0 subnet but is not being allowed to reach my workstation because the firewall is blocking it. Why is the firewall blocking it ? I hope the explanation of my network is clear, please ask if you require further clarification. Thank you.

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• SVN checkout returns 400 error

  - by eboix

  I'm trying to download the http://code.opencv.org/svn/opencv/trunk/ repository of all of the OpenCV source code - as specified in an OpenCV installation tutorial. In the tutorial, the repository https://code.ros.org/svn/opencv/trunk/ is used, but they moved it to http://code.opencv.org/svn/opencv/trunk/, and now you need a password to access the code.ros.org repository. Anyway, I'm using TortoiseSVN to download the SVN repository. (I get the same error with http://sourceforge.net/projects/win32svn/) I get this: Checkout from http://code.opencv.org/svn/opencv/trunk, revision HEAD, Fully recursive, Externals included Server sent unexpected return value (400 Bad request. Method Unknown) in response to REPORT request for '/svn/opencv/!svn/vcc/default' On the TortoiseSVN site I found something about this 400 error: You're behind a firewall which blocks DAV requests. Most firewalls do that. Either ask your Administrator to change the firewall, or access the repository with https:// instead of http:// like in https://svn.collab.net/repos/svn/ That way you connect to the repository with SSL encryption, which firewalls can't interfere with (if they don't block the SSL port completely). Also some virus scanners (i.e. Kapersky) are known to interfere and cause this error. The code.ros.org repository is https://, so I would be able to access it, but I need a password, so I can't. I made an account on ros.org, but it seems that I still need a password (which I don't know) to access the code repository. My username-password combination does not work. I unblocked all of the TortoiseSVN programs in my firewall settings. Nothing changed. I temporarily stopped my firewall to see if it was interfering with my request. I got the same error. How can I do an svn checkout http://code.opencv.org/svn/opencv/trunk/opencv/ so that I don't get this error? Is there any way to make it https://? Any help would be appreciated!

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• iTunes Home Sharing only works one way between 2 Windows XP PC's on the same LAN

  - by scunliffe

  Both PC's have the latest iTunes installed. PC (A) can "see" that there is a shared library "B library" but attempts to connect to it return this error message: The shared library "{Username}'s Library" is not responding (-3259) Check that any firewall software running on either the shared computer or this computer has been set to allow communication on port 3689. however the reverse works fine. e.g. PC (B) can "see" shared library "A library" and can access all content. Notes: Both PC's have Home Sharing enabled (turned off/on several times to verify). Both PC's have Windows Firewall turned on, but in the exceptions tab, iTunes is allowed, and Port 3689 is also added as a firewall exception (just in case) Both iTunes accounts have been "authorized" on both PC's Both PC's connect via LAN via D-Link DIR-615 router. In the advanced application rules, iTunes has also been added to allow traffic on port 3689 un-hindered. Is there any other magical setting/configuration option that I should be aware of and set in order to get this to work? I could care less about sharing apps etc. I just want the music sharing to work. Update: Solved! It turns out on PC (B) there were multiple accounts set up. 1 of the accounts had the checkbox checked under the Windows firewall "On" option which states "No exceptions" thus even though it was added to the exception list on the main user account, this other account was blocking access.

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• Trouble connecting to a local SQL server instance from the web

  - by dfarney

  We have a small network behind a firewall (WatchGuard XTM 2 series) and network switch. On our network we have multiple instances of SQL server, but 1 in specific that I would like to be able to access remotely from our website. We have a static IP address from our ISP and then all the machines on the network have a locally assigned dynamic IP address. When trying to connect to the database from outside our network how do I get the request to be directed to the proper machine / SQL instance? Is it a parameter in my connection string or something in my firewall? A few things to rule out: 1) The firewall is allowing access from the website to our network. I added the site's IP and opened up port 1433. Also, when trying to connect and monitoring the firewall no exceptions come up as they did before I added the proper IP address. 2) Remote connections on the SQL server has been setup and enabled. I've done a lot of reading up on remote connections and I am sure it has been setup properly. I am currently getting this error message on my site: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.)

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• Sending eMails in a external subnet in vmware ESXi

  - by user80658

  This might be a bit hard for me to explain - and it is a pretty individual situation. I got a native server at Hetzner (www.hetzner.de). The public IP is 88.[...].12. I got ESXi running on this server. I can access the esxi console by the public ip, but none of the virtual machines. That's why I bought a public subnet with 8 (6 usable) IPs (46.[...]) and an additional public ip (88.[...].26). This additional public ip belongs to the first virtual maschine - a firewall appliance - which is connected to the WAN. This need to be done this way - since it is the official way by hetzner. My 46. subnet is behind the firewall. I got a virtualmin server with dovecot imap/pop3 server. When sending a email, most provider (gmail) will accept those mails, but a lot will put it into spam (aol). My theory is: The MX line of my domain says of course the ip of the virtual machine (46.[...]), but in the raw email it says that email is sent by the ip of the firewall (88.[...].26), which doesnt sound trustworthy. A solution would be if the firewall could handle mail, but it simply cant. How can I prevent this problem? Thanks.

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• Linux iptables / conntrack performance issue

  - by tim

  I have a test-setup in the lab with 4 machines: 2 old P4 machines (t1, t2) 1 Xeon 5420 DP 2.5 GHz 8 GB RAM (t3) Intel e1000 1 Xeon 5420 DP 2.5 GHz 8 GB RAM (t4) Intel e1000 to test linux firewall performance since we got bitten by a number of syn-flood attacks in the last months. All machines run Ubuntu 12.04 64bit. t1, t2, t3 are interconnected through an 1GB/s switch, t4 is connected to t3 via an extra interface. So t3 simulates the firewall, t4 is the target, t1,t2 play the attackers generating a packetstorm thorugh (192.168.4.199 is t4): hping3 -I eth1 --rand-source --syn --flood 192.168.4.199 -p 80 t4 drops all incoming packets to avoid confusion with gateways, performance issues of t4 etc. I watch the packet stats in iptraf. I have configured the firewall (t3) as follows: stock 3.2.0-31-generic #50-Ubuntu SMP kernel rhash_entries=33554432 as kernel parameter sysctl as follows: net.ipv4.ip_forward = 1 net.ipv4.route.gc_elasticity = 2 net.ipv4.route.gc_timeout = 1 net.ipv4.route.gc_interval = 5 net.ipv4.route.gc_min_interval_ms = 500 net.ipv4.route.gc_thresh = 2000000 net.ipv4.route.max_size = 20000000 (I have tweaked a lot to keep t3 running when t1+t2 are sending as many packets as possible). The result of this efforts are somewhat odd: t1+t2 manage to send each about 200k packets/s. t4 in the best case sees aroung 200k in total so half of the packets are lost. t3 is nearly unusable on console though packets are flowing through it (high numbers of soft-irqs) the route cache garbage collector is no way near to being predictable and in the default setting overwhelmed by very few packets/s (<50k packets/s) activating stateful iptables rules makes the packet rate arriving on t4 drop to around 100k packets/s, efectively losing more than 75% of the packets And this - here is my main concern - with two old P4 machines sending as many packets as they can - which means nearly everyone on the net should be capable of this. So here goes my question: Did I overlook some importand point in the config or in my test setup? Are there any alternatives for building firewall system especially on smp systems?

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• What other ways can I load balance EC2 servers without using Elastic Load Balancing?

  - by undefined

  I have a web application that consists of a web server managed by a web hosting firm, a set of EC2 instances in amazons cloud and a MySQL database (hosted on the webserver). MySQL is behind a firewall and is set to allow access from Localhost and from a single IP address which is an Amazon Elastic IP address that is attached to the EC2 instance I have been running up to now. The problem is that I want to look at my scaling up and load balancing strategy for my EC2 instance. To this end I have been investigating the Elastic Load Balancers and Autoscaling tools that Amazon provides and have managed to set this up fine but for one thing - connecting to the MySQL database running on my webserver. I realised (thanks to answers on Serverfault) that I needed to check firewall settings and add the IP address for the load balancer, however Elastic Load Balancers provide you with a DNS name, not an IP address and infact the IP addresses change over time so this will not work. I have been told by the company hosting the database that the way the firewall works is to look up the IP address of the DNS name and store the IP rather than the DNS name. so basically this will not work and the only way to allow access would be to open up the SQL port to allow access from anyone! Is this a viable idea? Should I look at moving my database into the cloud? Is there another firewall that the server company can use? Should I find another way of load balancing (if so what?) tricky one eh? any help appreciated!

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• MSDTC - Communication with the underlying transaction manager has failed (Firewall open, MSDTC netwo

  - by SocialAddict

  I'm having problems with my ASP.NET web forms system. It worked on our test server but now we are putting it live one of the servers is within a DMZ and the SQL server is outside of that (on our network still though - although a different subnet) I have open up the firewall completely between these two boxes to see if that was the issue and it still gives the error message "Communication with the underlying transaction manager has failed" whenever we try and use the "TransactionScope". We can access the data for retrieval it's just transactions that break it. We have also used msdtc ping to test the connection and with the amendments on the firewall that pings successfully, but the same error occurs! How do i resolve this error? Any help would be great as we have a system to go live today. Panic :)

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