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• How to reject messages to unknown user in sendmail cooperating with MS-Exchange?

  - by user71061

  Hi! I have an MS Exchange 2003 configured as a mail server for an organization. As this server is located in this organization internal network and I don't want to expose it directly over internet, I have second server - linux box with sendmail - configured as intelligent relay (it accept all messages from internet addressed to @my_domain, and forward it to internal Exchange serwer, and accepts all messages from this internal Exchange server and forward it over internet). This configuration work's fine, but I want to eliminate messages addressed to not exiting users as early as possible. Good solution could be Enabling on Exchange server function of filtering recipients together with "tar pitting", but in my case this dosn't solve problem, because before any message reach my Exchange server (which could eventually reject it), it has to be already accepted by sendmail server, sitting in front of this Exchange server. So, I want to configure my sendmail server in such a way, that during initial SMTP conversation it could query somehow my Exchange server checking whether recipient address is valid or not, and based on result of this query, accept or reject (possibly with some delay) incoming message in a very early phase. In fact, I have already solved this issue by writing my own, simple sendmail milter program which checks recipient address against text file with list of valid addresses. But this solution is not satisfying me any longer, because it requires frequent updates of this file, and due to lack of time/motivation/programming skills, I don't want to cope further with my source code, adding to it functionality of querying my Exchange server. Maybe I can achieve desired effect by configuring any component of already available linux software. Any ideas?

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• How can I use wildcards in an Nginx map directive?

  - by Ian Clelland

  I am trying to use Nginx to served cached files produced by a web application, and have spotted a potential problem; that the url-space is wide, and will exceed the Ext3 limit of 32000 subdirectories. I would like to break up the subdirectories, making, say, a two-level filesystem cache. So, where I am currently caching a file at /var/cache/www/arbitrary_directory_name/index.html I would store that instead at something like /var/cache/www/a/r/arbitrary_directory_name/index.html My trouble is that I can't get try_files, or even rewrite to make that mapping. My searching on the subject leads me to believe that I need to do something like this (heavily abbreviated): http { map $request_uri $prefix { /aa* a/a; /ab* a/b; /ac* a/c; ... /zz* z/z; } location / { try_files /var/cache/www/$prefix/$request_uri/index.html @fallback; # or # if (-f /var/cache/www/$prefix/$request_uri/index.html) { # rewrite ^(.*)$ /var/cache/www/$prefix/$1/index.html; # } } } But I can't get the /aa* pattern to match the incoming uri. Without the *, it will match an exact uri, but I can't get it to match just the first two characters. The Nginx documentation suggests that wildcards should be allowed, but I can't see a way to get them to work. Is there a way to do this? Am I missing something simple? Or am I going about this the wrong way?

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• Hadoop streaming job on EC2 stays in "pending" state

  - by liamf

  Trying to experiment with Hadoop and Streaming using cloudera distribution CDH3 on Ubuntu. Have valid data in hdfs:// ready for processing. Wrote little streaming mapper in python. When I launch a mapper only job using: hadoop jar /usr/lib/hadoop/contrib/streaming/hadoop-streaming*.jar -file /usr/src/mystuff/mapper.py -mapper /usr/src/mystuff/mapper.py -input /incoming/STBFlow/* -output testOP hadoop duly decides it will use 66 mappers on the cluster to process the data. The testOP directory is created on HDFS. A job_conf.xml file is created. But the job tracker UI at port 50030 never shows the job moving out of "pending" state and nothing else happens. CPU usage stays at zero. (the job is created though) If I give it a single file (instead of the entire directory) as input, same result (except Hadoop decides it needs 2 mappers instead of 66). I also tried using the "dumbo" Python utility and launching jobs using that: same result: permanently pending. So I am missing something basic: could someone help me out with what I should look for? The cluster is on Amazon EC2. Firewall issues maybe: ports are enabled explicitly, case by case, in the cluster security group.

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• Apache suddenly very slow on http and faster on https

  - by hsnm

  Background: I have Apache 2 running on ubuntu. There is a low usage on it and mostly being accessed for a web service URL from mobile apps. It was working fine until I installed SSL certificates. I now have both http and https. When I access the server using https, I get a fairly quick response (but probably not as fast as before). When I use http, it's so slow. What I tried: From this post: I curl localhost from the host and it takes some time, meaning there is no routing issue. The server runs on Amazon EC2 instance and is managed by me only. Also: I see that Apache once running, creates the maximum number of processes it is allowed to, which was not the case before. I lowered the MaxClients to 20 and I think I'm getting faster responses but it still takes over a minute and I always have MaxClients Apache processes. dmesg returns many [ 1953.655703] TCP: Possible SYN flooding on port 80. Sending cookies. When I netstat I get many entries with SYN_RECV. Possibly a DDoS attack? From EC2's monitoring diagrams I see a pattern of high "Maximum Network In (Bytes)" since 2 days ago. By the way the server is still being tested, the actual traffic is very low and not consistent. I tried to go with this solution to limit incoming connections using iptables, still no luck, but I'm trying. Question: What could be the problem? Is this a DDoS attack?

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• How could one track all emails sent from employees?

  - by Schnapple

  My client runs a small business. This business has a small number of employees. For various reasons, my client would like to be able to have a copy of all of the emails sent from their employees BCC'd to them. The net effect here would be similar to the access they would have if they hosted their email through Exchange but the business is too small to make this a feasible option. They are currently hosted through GoDaddy. I have not investigated it myself personally but apparently GoDaddy can do something along these lines for all incoming email but not for outgoing email. Is there a way to set up email accounts for a particular domain to where a specified admin user could be copied on all outgoing email? UPDATE: I've modified the title to reflect that it's employees not just users who are the goal here. Also I forgot to mention how they currently do email through GoDaddy - POP3. I think maybe IMAP is also possible through GoDaddy, not sure. And yes, the bottom line here is to basically emulate a feature of a larger-class platform through a smaller, cheaper platform. Opinion-only answers should probably be relegated to the comments. For the sake of argument let's say that any legal requirements have been met.

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• How to make gpg2 flush the stream?

  - by Vi

  I want to get some slowly flowing data saved in encrypted form at the device which can be turned off abruptly. But gpg2 seems to not to flush it's output frequently and I get broken files when I try to read such truncated file. vi@vi-notebook:~$ cat asdkfgmafl asdkfgmafl ggggg ggggg 2342 2342 cat behaves normally. I see the output right after input. vi@vi-notebook:~$ gpg2 -er _Vi --batch ?pE??x...(more binary data here)....???-??.... asdfsadf 22223 sdfsdfasf Still no data... Still no output... ^C gpg: signal Interrupt caught ... exiting vi@vi-notebook:~$ gpg2 -er _Vi --batch /tmp/qqq skdmfasldf gkvmdfwwerwer zfzdfdsfl ^\ gpg: signal Quit caught ... exiting Quit vi@vi-notebook:~$ gpg2 " 2048-bit ELG key, ID 78F446CA, created 2008-01-06 (main key ID 1735A052) gpg: [don't know]: 1st length byte missing vi@vi-notebook:~$ # Where is my "skdmfasldf" How to make gpg2 to handle such case? I want it to put enough output to reconstruct each incoming chunk of input. (Also fsyncing after each output can be benefitial as an additional option). Should I use other tool (I need pubkey encryption).

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• Manual NAT on Checkpoint (Redirect all http requests to a local web server)

  - by kulakli

  Hi, We have a proxy server in internal network and I want to redirect all internet http requests to a web server in local network. It'll be like a Network Billboard that say "No direct connection is available. Set up your proxy etc." For example: A user starts the computer Opens the browser Trys to open www.google.com Should see web server output on local network Trys another web site on internet Should see web server output on local network Sets up proxy Trys to connect to a web site Web site should be loaded I have added a simple manual NAT rule to address translation in Checkpoint firewall but it simply does not work. Here is my address translation rule Source Destination Service T.Source T.Destination T.Service MY_PC A_GOOGLE_IP ALL ORIGINAL INT_WEB_SRV ORIGINAL Then when I ping A_GOOGLE_IP, replies come from INT_WEB_SRV, as I expected. However, when I try to connect A_GOOGLE_IP from browser (http://A_GOOGLE_IP), No replies come from SYN_SENT and falls into timeout. When I look at the firewall log of INT_WEB_SRV, I can see the incoming connection requests from MY_PC is accepted and NO denies. By the way, there is no problem to see INT_WEB_SRV (http://INT_WEB_SRV) from browser. My understanding is, my nat rule at checkpoint NGX R60 does not include return packets. I definitely need some help. Regards, Burak

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• Amazon EC2: Instances, IPs and a wordpress blog (LAMP)

  - by JustinXXVII

  I had a link to my blog posted on Reddit yesterday and MySQL crashed on my EC2 Micro instance. I know I didn't have that many visitors because I used a marketing link that tracks hits. The link got 167 hits over the course of the last 18 hours, and MySQL crashed twice. So anyway, 167 visits is not a lot, so I've done some short term optimizations like restricting the number of Apache threads to limit the MySQL calls. I also set up WP Super Cache to serve static content. Soon I'm going to offload all of my images to S3 or CloudFront. So this leads me to my question. If this doesn't seem to help, and if i have another traffic "spike", how do AMIs work when you have a MySQL database? I think I understand that if you have more than one instance and assign the same Elastic IP to both of them, the incoming traffic gets distributed among both. But what happens when the MySQL database gets updated on one of the instances? I just need to wrap my mind around what happens when I create an AMI and then launch a new instance to help with traffic. Thanks for your suggestions.

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• High speed network configuration

  - by Peter M

  Sorry if this seems to be a stupid question, I'm not sure how to specify what I want to know when checking google. I will have 2 or 3 devices pumping out data on a 100Base-T port. The combined data rate of all devices is about 15KB/S which exceeds the optimal 100Base-T channel capacity (12KB/S), but well within the realms of a 1000Base-T connection. Each device will be sending a burst of data in the form of an FTP transfer to a common, single host computer in a sequential manner ie: Device A establishes FTP connection and transfers data Device B establishes FTP connection and transfers data Device C establishes FTP connection and transfers data It may be that the A&B, B&C and C&A transfers overlap in the time domain to some extent. There will be minimal traffic going back from the computer to each device (in general what ever is needed to support the FTP transfers), and the network will be dedicated to transferring data between these devices and the host computer. Is it possible to use a switch to combine the multiple incoming 100Base-T streams into a single outgoing 1000Base-T stream? if so what features in a switch should I be looking for? Or would it be better to have 3 physical point-to-point 100Base-T dedicated connections between each device and the host computer? (thus having at least 3 physical Ethernet interfaces on that computer) Note that I can't change the interface on the devices, but I am free to choose the network and host computer configuration. Thanks for you help Peter

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• Plesk FTP not working but SFTP and Shell is working

  - by shamittomar

  I am facing a strange problem. The FTP on my Plesk VPS is not working. Whenever I try to connect, FileZilla FTP client says: Status: Resolving address of xxxxxxxxxxxxx.com Status: Connecting to xxx.xxx.xxx.xxx:21... Status: Connection established, waiting for welcome message... Error: Could not connect to server So, it's not even going to the step of asking username/password. So, it's something else. The SFTP on port 22 is working fine. Also, I can successfully do shell access and run commands. But, I NEED FTP access too on port 21. I have searched everywhere but can not find any setting to enable it. This is the Plesk version info: Parallels Plesk Panel version 9.5.2 Operating system Linux 2.6.26.8-57.fc8 CPU GenuineIntel, Intel(R) Pentium(R) 4 CPU 3.00GHz Any help is appreciated. [EDIT]: The firewall is not blocking it. I have checked it on server and there are absolutely no blocking rule. Firewall states: All incoming/outgoing connections are accepted on FTP And on client-side (my PC), I can connect to other FTP servers so this is not an issue in my PC's firewall. Moreover, I can not even connect to the FTP from online FTP clients like net2ftp.

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• How can I stop SipVicious ('friendly-scanner') from flooding my SIP server?

  - by a1kmm

  I run an SIP server which listens on UDP port 5060, and needs to accept authenticated requests from the public Internet. The problem is that occasionally it gets picked up by people scanning for SIP servers to exploit, who then sit there all day trying to brute force the server. I use credentials that are long enough that this attack will never feasibly work, but it is annoying because it uses up a lot of bandwidth. I have tried setting up fail2ban to read the Asterisk log and ban IPs that do this with iptables, which stops Asterisk from seeing the incoming SIP REGISTER attempts after 10 failed attempts (which happens in well under a second at the rate of attacks I'm seeing). However, SipVicious derived scripts do not immediately stop sending after getting an ICMP Destination Host Unreachable - they keep hammering the connection with packets. The time until they stop is configurable, but unfortunately it seems that the attackers doing these types of brute force attacks generally set the timeout to be very high (attacks continue at a high rate for hours after fail2ban has stopped them from getting any SIP response back once they have seen initial confirmation of an SIP server). Is there a way to make it stop sending packets at my connection?

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• Looking for ballpark pricing on an affordable a Cisco VOIP solution for our office

  - by guytech

  We have about 8 incoming PSTN lines that are currently on an old and antiquated Nortel Meridian ICS system. This system has been giving us some grief. We're looking for a new VOIP solution. I've been looking at a Cisco solution and it does seem pricey but I'm sure effective. Unfortunately, we probably can't afford a Cisco Unified Communications 520 which seems to be the ideal solution. We have about 15 people who need an extension and voicemail. We really don't have any need for a fancy system just an auto attendant of some sort when people call us. It looks like we'll have to get an older router and an addon card for what we're looking for to get best value pricing. However, I don't know a a lot about Cisco voice products so I'm a bit lost as to what to get. The only thing I am sure on is the pricing on VOIP phones which we expect to be about ~$100-200. However, I'm not sure what pieces of VOIP infrastructure to get. Any advice? I am familiar with Asterisk but right now I'm looking on pricing concerning a Cisco solution.

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• Configuring two nearby WLANs: should I use the same ssid?

  - by Rory

  I'm configuring a home network for basic internet use (ie don't really need connectivity between workstations on the network). My brick walls mean a single wireless router doesn't provide good coverage throughout the house, so I have purchased two powerline adapters and now have the incoming modem/wireless router at one end of the house plugged into a powerline adapter, and at the other end of the house the other powerline adapter plugged into another wireless router. Currently the two wireless networks have different ssids. (The powerline adapters only do power-Ethernet; they're not wireless access points themselves.) This works well, except when I move between rooms and would ideally like my devices (iPad, phones, laptops) to switch from the weak to the strong signal. Sometimes there's enough signal that they hold on to the weak connects instead of switching to the strong one. Should I name the two networks the same ssid, and if so what is the actual effect? Do the signals get confused, is the bandwidth affected, will this help my devices seamlessly move from one to the other, or is the ssid just a cosmetic thing that actually doesn't have any impact on this situation? Are there any other settings that I should configure to make my setup optimal?

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• Apache + Tomcat: Which one should handle SSL? IP-based proxy forwarding?

  - by delirial

  We currently have a Tomcat application running with SSL on port 443. Right now we have an apache server that accepts http requests on port 80 and redirects to the Tomcat instance: <VirtualHost *:80> ServerName domain.com ServerAlias domain.com <LocationMatch "/"> Redirect permanent / https://domain.com/ </LocationMatch> </VirtualHost> Tomcat is handling SSL, because there's no proxy, just a simple redirect to the SSL port: <Connector port="443" maxThreads="200" scheme="https" secure="true" SSLEnabled="true" keystoreFile="/app/ssl/domain_com.jks" keystorePass="ourpassword" clientAuth="false" sslProtocol="TLS"/> We want to begin using the apache web server as a proxy and additionally, do per-IP redirects to certain apps that should only be used by hosts on a pre-determined IP range. We would also like to redirect IPs that don't match the pre-determined list to a static html page hosted on the apache server. My first question is: Should I continue to handle SSL on Tomcat's end, or should I use apache with SSL while forwarding to an "unprotected" tomcat port? Is there any way to redirect to different apps (and potentially hosts) depending on the incoming IP? thanks, del

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• How could one archive all emails sent from employees?

  - by Schnapple

  My client runs a small business. This business has a small number of employees. They are currently hosted through GoDaddy for web and email. For legal reasons the client would like to archive emails sent by their employees. Currently the emails are all done through POP3 so all the email is basically housed in files on individual machines (remember, small business). It's been proposed an inexpensive solution to this would be to have all emails BCC'd to a main account so that conversations with the outside would could be archived and tracked. I have not investigated it myself personally but apparently GoDaddy can do something along these lines for all incoming email but not for outgoing email. Is there a way to set up email accounts for a particular domain to where a specified admin user could be copied on all outgoing email? UPDATE: I've modified the title to reflect employees not users. The goal of this is to archive sent emails for legal reasons. This is something the employees will be cognizant of and on board with. The bottom line here is to basically emulate a feature of a larger-class platform through a smaller, cheaper platform. If the answer is "can't do it, buy an Exchange license" that's fine. My apologies for phrasing this so poorly. I understand why there was so much confusion.

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• Routing for remote gateway over VPN in Vista/7 broken?

  - by Raymond

  Hi, Situation is as follows. Home computer running Windows 7, sets up VPN connection (LT2P + IPSec, "use remote gateway" disabled) to office. Subnet is 192.168.64.x Office has Draytek Vigor 2920 router, subnet is 192.168.32.x What happens? - VPN connection itself works fine - Can ping any machine on the remote network - When trying to open a webpage from a host in the remote network, the remote server logs the incoming request, but the browser hangs on "waiting for..." and eventually times out. I have observed this problem on Windows Vista and Windows 7. On Windows XP however there is no problem like described above. The only clue I have is that there is a difference in the routing between XP and Vista/7. The output of "route print" on Windows XP looks like this: (See www.latunyi.com/routing_xp.png) So here the gateway for the 192.168.32.x subnet is the IP address that the local computer has in the remote network. The output of "route print" on Windows 7 (and Windows Vista) looks like this: (See www.latunyi.com/routing_win7.png") Now the gateway for the 192.168.32.x subnet is the IP address of the VPN router (32.1). I don't know if that causes this trouble, but it seems a bit strange. Enabling "use default gateway on remote network" doesn't make a difference. Using the new option "Disable class based route addition" in Windows 7 only makes the route to the VPN router disappear. I am really puzzled here. I assume the VPN routing can't be broken in both Vista and Windows 7, and this should just work without manually adding routes. I hope someone has a solution for this problem :-). Thanks!

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• What can I do with a home server?

  - by Joel Coehoorn

  I have an old 700 Mhz Pentium III at home running Windows 2000 Server, with a home router set up to pass incoming requests to it and a DynDNS account set up so it's easy to find. Right now I'm using it for a number of things: Shared folders + backup inside the home network Shared Printer inside the home network Domain Controller, just because I feel like it and because it's useful to me as practice to keep those "enterprise" administration skills. Web Server FTP remote access for my files. I abandoned this for security reasons, but it's still worth leaving visible. Remote Desktop in to the home network (thinking about adding VPN service) SVN repository MySQL - Will be moving to SQL Server 2008 Standard soon. After I upgrade my wife's laptop from home to pro later this year it will also become a domain controller It's the only place I still have access to Internet Explorer 6 any more without setting up a new virtual machine, so I use it for testing code with that browser. The question is: What else could I be doing with this machine? Update Additional ideas based on the suggestions: Media Server/DVR Build server PBX SSH Proxy Server Continuous Integration Server Personal OpenID Provider Update2 Just a note that this server was recently upgraded to an Atom330 with 2 GB ram and bigger hard drive. For all that's slow for a "modern" cpu, it should still be much faster than the old Pentium III and the expected power savings should make the upgrade essentially free over the course of the next year or two. Also, it's now running Windows Server 2008.

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• Can Haproxy deny a request by IP if its stick-table is full?

  - by bantic

  In my haproxy configs I'm setting a stick-table of size 5 that stores every incoming IP address (for 1 minute), and it is set as nopurge so new entries won't get stored in the table. What I'd like to have happen is that they would get denied, but that isn't happening. The stick-table line is: stick-table type ip size 5 expire 1m nopurge store gpc0 And the whole configs are: global maxconn 30000 ulimit-n 65536 log 127.0.0.1 local0 log 127.0.0.1 local1 debug stats socket /var/run/haproxy.stat mode 600 level operator defaults mode http timeout connect 5000ms timeout client 50000ms timeout server 50000ms backend fragile_backend tcp-request content track-sc2 src stick-table type ip size 5 expire 1m nopurge store gpc0 server fragile_backend1 A.B.C.D:80 frontend http_proxy bind *:80 mode http option forwardfor default_backend fragile_backend I have confirmed (connecting to haproxy's stats using socat readline /var/run/haproxy.stat) that the stick-table fills up with 5 IP addresses, but then every request after that from a new IP just goes straight through -- it isn't added to the stick-table, nothing is removed from the stick-table, and the request is not denied. What I'd like to do is deny the request if the stick-table is full. Is this possible? I'm using haproxy 1.5.

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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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• Watchguard Firebox "split" fibre optic line into 2 interfaces

  - by fRAiLtY-

  We have a requirement on our Watchguard Firebox XTM505 to be able to split our incoming external interface, in this case a fibre optic dedicated leased line, 100/100. We use the line in our office of approx 30 machines however we also re-sell to an external company who utilise it to provide wireless internet solutions to the public. The current infrastructure is as follows: Data in (Leased Line) - Juniper SRX210 managed by ISP - 1 cable out into unmanaged Netgear switch - 1 cable into our firewall and office network, 1 cable to our external providers core router managed by them. We have been informed that having the unmanaged switch in the position it is poses a security risk and that a good option would be to get our Watchguard Firewall to perform the split, by separating our office onto a trusted interface, and by "passing through" the external line to their managed router. It is alleged that the Watchguard is capable of doing this and also rate limiting the interfaces, i.e. 20mbps for the trusted interface and 80mbps for the "pass-through", however Watchguard technical support don't seem to be able to understand what we're trying to achieve. Can anyone provide any advice on whether this is possible on a Watchguard device and how or perhaps if there's a better way of achieving this, perhaps with a managed switch instead of unmanaged? Cheers

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• Diagnosing Random Network Lag

  - by uesp

  I'm having trouble diagnosing some random lag on a 6 server LAMP cluster serving a MediaWiki site. While we're serving some 100 pages/sec the servers themselves are running fine with less than 0.5 load, no locked processes, no paging, no errors being logged, etc.... Lag is present on all servers and is random: one minute its fine the next it's there. DNS lookups on the servers are randomly slow. For example time nslookup google.com varies randomly from a few milliseconds to several seconds and sometimes times out entirely. While we use IP addresses internally on the cluster this may be a symptom of the root issue. We are not running our own DNS server. The Apache server-status pages randomly lag or time out. Benchmarking using ab between servers shows a few loads sometimes take 3000 ms (almost exactly). Benchmarking server-status on the local server itself usually shows no issue (it showed a lag only once among a few hundred tests). The servers are sitting behind a switch and a firewall which I don't have any access to so I don't know their setup or status. While we are under heavier than normal load a 2 Mbps incoming and 20 Mbps outgoing traffic shouldn't be stressing the switch or firewall should it? My feeling is that it is the switch/firewall or something above them in the ISP like their DNS but can't confirm it. I need some other tests or methods of diagnosing this lag to try and narrow down the ultimate cause.

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• Log connections to program

  - by Zac

  Besides for using iptables to log incoming connections.. Is there a way to log established inbound connections to a service that you don't have the source to (suppose the service doesn't log stuff like this on its own)? What I'm wanting to do is gather some information based on who's connecting to be able to tell things like what times of the day the service is being used the most, where in the world the main user base is, etc. I am aware I can use netstat and just hook it up to a cron script, but that might not be accurate, since the script could only run as frequently as a minute. Here is what I am thinking right now: Write a program that constantly polls netstat, looking for established connections that didn't appear in the previous poll. This idea seems like such a waste of cpu time though, since there may not be a new connection.. Write a wrapper program that accepts inbound connections on whatever port the service runs on, but then I wouldn't know how to pass that connection along to the real service. Edit: Just occurred to me that this question might be better for stackoverflow, though I am not certain. Sorry if this is the wrong place.

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• Serving static content with Apache web server and Tomcat

  - by Hunter

  I've configured Apache web server and Tomcat like this: I created a new file in apache2/sites-available, named it "myDomain" with this content: <VirtualHost *:80> ServerAdmin [email protected] ServerName myDomain.com ServerAlias www.myDomain.com ProxyPass / ajp://localhost:8009 <Proxy *> AllowOverride AuthConfig Order allow,deny Allow from all Options -Indexes </Proxy> </VirtualHost> Enabled mod_proxy and myDomain a2enmod proxy_ajp a2ensite myDomain Edited Tomcat's server.xml (inside the Engine tag) <Host name="myDomain.com" appBase="webapps/myApp"> <Context path="" docBase="."/> </Host> <Host name="www.myDomain.com" appBase="webapps/myApp"> <Context path="" docBase="."/> </Host> This works great. But I don't like to put static files (html, images, videos etc.) into {tomcat home}/webapps/myApp's subfolders instead I'd like to put them the apache webserver's root WWW directory's subdirectories. And I'd like Apache web server to serve these files alone. How could I do this? So all incoming request will be forwarded to Tomcat except those that ask for a static file.

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• Splitting an HTTP request into multiple byte-range requests

  - by redpola

  I have arrived at the unusual situation of having two completely independent Internet connections to my home. This has the advantage of redundancy etc but the drawback that both connections max out at about 6Mb/s. So one individual outbound http request is directed by my "intelligent gateway" (TP-LINK ER6120) out over one or the other connection for its lifetime. This works fine over complex web pages and utilises both external connects fine. However, single-http-request downloads are limited to the maximum rate of one of the two connections. So I'm thinking, surely I can setup some kind of proxy server to direct all my http requests to. For each incoming http request, the proxy server will issue multiple byte-range requests for the desired data and manage the reassembly and delivery of that data to the client's request. I can see this has some overhead, and also some edge cases where there will be blocking problems waiting for data. I also imagine webmasters of single-servers would rather I didn't hit them with 8 byte-range requests instead of one request. How can I achieve this http request deconstruct/reconstruction? Or am I just barking mad?

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• Seeing traffic destined for other people's servers in wireshark

  - by user350325

  I rent a dedicated server from a hosting provider. I ran wireshark on my server so that I could see incoming HTTP traffic that was destined to my server. Once I ran wireshark and filtered for HTTP I noticed a load of traffic, but most of it was not for stuff that was hosted on my server and had a destination IP address that was not mine, there were various source IP addresses. My immediate reaction was to think that somebody was tunnelling their HTTP traffic through my server somehow. However when I looked closer I noticed that all of this traffic was going to hosts on the same subnet and all of these IP addresses belonged to the same hosting provider that I was using. So it appears that wireshark was intercepting traffic destined for other customers who's servers are attached to the same part of the network as mine. Now I always assumed that on a switch based network that this should not happen as the switch will only send data to the required host and not to every box attached. I assume in this case that other customers would also be able to see data going to my server. As well as potential privacy concerns, this would surely make ARP poising easy and allow others to steal IP addresses (and therefor domains and websites)? It would seem odd that a network provider would configure the network in such a way. Is there a more rational explanation here?

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