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  • Problem with MSDE 2000 5 minute keepalive over ISDN

    - by mcrick
    We have a SQL Server transactionally pushing replicate data to an MSDE 2000 SP3a subscriber over ISDN. Prior to a recent upgrade to bring us to the MSDE 2000 level we pushed to MSDE 1. We are finding that there is now a 5 minute keepalive being instigated from MSDE 2000 which we cannot account for. Further, we can find no way to either disable it or lengthen the keepalive interval. Not surprisingly, we are finding a marked increase in ISDN line costs due to these previously non-existent keepalive packets! Please note that we are assuming that it is an MSDE 2000 server issue, but it could equally be some behaviour related to the way that replication is operating on MSDE 2000. Unfortunately, as yet, we have not identified a replication configuration parameter that affects the keepalive in any way. Can anyone advise how we might indentify a root cause for this problem (and ideally a fix)?

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  • TCP Keepalive and firewall killing idle sessions

    - by Carlos A. Ibarra
    In a customer site, the network team added a firewall between the client and the server. This is causing idle connections to get disconnected after about 40 minutes of idle time. The network people say that the firewall doesn't have any idle connection timeout, but the fact is that the idle connections get broken. In order to get around this, we first configured the server (a Linux machine) with TCP keepalives turned on with tcp_keepalive_time=300, tcp_keepalive_intvl=300, and tcp_keepalive_probes=30000. This works, and the connections stay viable for days or more. However, we would also like the server to detect dead clients and kill the connection, so we changed the settings to time=300,intvl=180,probes=10, thinking that if the client was indeed alive, the server would probe every 300s (5 minutes) and the client would respond with an ACK and that would keep the firewall from seeing this as an idle connection and killing it. If the client was dead, after 10 probes, the server would abort the connection. To our surprise, the idle but alive connections get killed after about 40 minutes as before. Wireshark running on the client side shows no keepalives at all between the server and client, even when keepalives are enabled on the server. What could be happening here? If the keepalive settings on the server are time=300,intvl=180,probes=10, I would expect that if the client is alive but idle, the server would send keepalive probes every 300 seconds and leave the connection alone, and if the client is dead, it would send one after 300 seconds, then 9 more probes every 180 seconds before killing the connection. Am I right? One possibility is that the firewall is somehow intercepting the keepalive probes from the server and failing to pass them on to the client, and the fact that it got a probe makes it think that the connection is active. Is this common behavior for a firewall? We don't know what kind of firewall is involved. The server is a Teradata node and the connection is from a Teradata client utility to the database server, port 1025 on the server side, but we have seen the same problem with an SSH connection so we think it affects all TCP connections.

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  • KeepAlive packets over a Soap request

    - by Nycto
    I've been debugging some Soap requests we are making between two servers on the same VLAN. The app on one server is written in PHP, the app on the other is written in Java. I can control and make changes to the PHP code, but I can't affect the Java server. The PHP app forms the XML using the DOMDocument objects, then sends the request using the cURL extension. When the soap request took longer than 5 minutes to complete, it would always wait until the max timeout limit and exit with a message like this: Operation timed out after 900000 milliseconds with 0 bytes received After sniffing the packets that were being sent, it turns out that the problem was caused by a 5 minute timeout in the network that was closing what it thought was a stale connection. There were two ways to fix it: bump up the timeout in iptables, or start sending KeepAlive packets over the request. To be thorough, I would like to implement both solutions. Bumping up the timeout was easy for ops to do, but sending KeepAlive packets is turning out to be difficult. The cURL library itself supports this (see the --keepalive-time flag for the CLI app), but it doesn't appear that this has been implemented in the PHP cURL library. I even checked the source to make sure it wasn't an undocumented feature. So my question is this: How the heck can I get these packets sent? I see a few clear options, but I don't like any of them: Write a wrapper that will kick off the request by shell_execing the CLI app. This is a hack that I just don't like Update the cURL extension to support this. This is a non-option according to Ops. Open the socket myself. I know just enough to be dangerous. I also haven't seen a way to do this with fsockopen, but I could be missing something. Switch to another library. What exists that supports this? Thanks for any help you can offer.

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  • Richfaces modal panel and a4j:keepAlive

    - by mykola
    Hello! I've got unexpected problems with richfaces (3.3.2) modal panel. When i try to open it, browser opens two panels instead of one: one is in the center, another is in the upper left corner. Besides, no fading happens. Also i have three modes: view, edit, new - and when i open my panel it should show either "Create new..." or "Edit..." in the header and actually it shows but not in the header as the latter isn't rendered at all though it should, because i set proper mode in action before opening this modal panel. Besides it works fine on all other pages i've made and there are tens of such pages in my application. I can't understand what's wrong here. The only way to fix it is to remove <a4j:keepAlive/> from the page that is very strange, imho. I'm not sure if code will be usefull here as it works fine everywhere in my application but this only case. So if you put it on your page it will probably work without problems. My only question is: are there any hidden or rare problems in interaction of these two elements (<rich:modalPanel> and <a4j:keepAlive>)? Or shall i spent another two or three days searching for some wrong comma, parenthesis or whatever in my code? :) For most curious. Panel itself: <!-- there's no outer form --> <rich:modalPanel id="panel" autosized="true" minWidth="300" minHeight="200"> <f:facet name="header"> <h:panelGroup id="panelHeader"> <h:outputText value="#{msg.new_smth}" rendered="#{MbSmth.newMode}"/> <h:outputText value="#{msg.edit_smth}" rendered="#{MbSmth.editMode}"/> </h:panelGroup> </f:facet> <h:panelGroup id="panelDiv"> <h:form > <!-- fields and buttons --> </h:form> </h:panelGroup> </rich:modalPanel> One of the buttons that open panel: <a4j:commandButton id="addBtn" reRender="panelHeader, panelDiv" value="#{form.add}" oncomplete="#{rich:component('panel')}.show()" action="#{MbSmth.add}" image="create.gif"/> Action invoked on button click: public void add() { curMode = NEW_MODE; // initial mode is VIEW_MODE newSmth = new Smth(); } Mode check: public boolean isNewMode() { return curMode == NEW_MODE; } public boolean isEditMode() { return curMode == EDIT_MODE; }

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  • MacFUSE: Keepalive?

    - by Wilco
    Is there a way to configure MacFUSE to keep a mounted volume alive if the remote host is set to break the connection due to inactivity? If there is no direct way to configure this, would there be a way to write a script to accomplish this?

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  • Problem with MSDE 2000 5 minute keepalive over ISDN

    - by mcrick
    We have a SQL Server transactionally pushing replicate data to an MSDE 2000 SP3a subscriber over ISDN. Prior to a recent upgrade to bring us to the MSDE 2000 level we pushed to MSDE 1. We are finding that there is now a 5 minute keepalive being instigated from MSDE 2000 which we cannot account for. Further, we can find no way to either disable it or lengthen the keepalive interval. Not surprisingly, we are finding a marked increase in ISDN line costs due to these previously non-existent keepalive packets! Please note that we are assuming that it is an MSDE 2000 server issue, but it could equally be some behaviour related to the way that replication is operating on MSDE 2000. Unfortunately, as yet, we have not identified a replication configuration parameter that affects the keepalive in any way. Can anyone advise how we might indentify a root cause for this problem (and ideally a fix)?

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  • How can I measure TCP timeout limit on NAT firewall for setting keepalive interval?

    - by jmanning2k
    A new (NAT) firewall appliance was recently installed at $WORK. Since then, I'm getting many network timeouts and interruptions, especially for operations which would require the server to think for a bit without a response (svn update, rsync, etc.). Inbound SSH sessions over VPN also timeout frequently. That clearly suggests I need to adjust the TCP (and ssh) keepalive time on the servers in question in order to reduce these errors. But what is the appropriate value I should use? Assuming I have machines on both sides of the firewall between which I can make a connection, is there a way to measure what the time limit on TCP connections might be for this firewall? In theory, I would send a packet with gradually increasing intervals until the connection is lost. Any tools that might help (free or open source would be best, but I'm open to other suggestions)? The appliance is not under my control, so I can't just get the value, though I am attempting to ask what it currently is and if I can get it increased.

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  • Anything wrong with spamming GC.KeepAlive(KeyboardHookPointer)?

    - by Alex
    GC.KeepAlive() References the specified object, which makes it ineligible for garbage collection from the start of the current routine to the point where this method is called. Not really sure about what GC.KeepAlive does other than simply store a reference so the Garbage Collector doesn't collect the object. But does calling GC.KeepAlive() on an object permanently keep an object from being collected? Or do you have to re-call GC.KeepAlive() every so often (and if so, how often)? I want to keep my keyboard hook alive.

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  • Apache KeepAlive in child location not working

    - by Mark Beaton
    I'm trying to turn keep-alive connections off for a requests to a child folder in Apache, but when I reload the config I get the following error: KeepAlive not allowed here Here's my vhost config: <VirtualHost *:80> ServerAdmin [email protected] ServerName example.com DocumentRoot /srv/www/mysite DirectoryIndex index.html <Location /subfolder> KeepAlive Off </Location> </VirtualHost> I've tried using <Directory> as well, but no go there either. Any ideas? I'd rather not turn keep-alive off for the whole site...

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  • GRE keepalive with Linux and RouterOS

    - by eri
    I have a Linux host and couple of routerboadrs. I created a GRE tunnel, but Linux does not answer keepalive packages. Then router mark gre connection as unreachable, so I cant send to Linux host from router subnet. If linux sends something into tunnel (ping, etc.) - RouterOS mark connection as reacheble. Second and next packages routed nicely until one minute idle (no traffic). Tunnel in linux a make in this way: remote=x.x.x.x dev=gre21 network=10.21.0.0/16 ip tunnel add ${dev} mode gre remote ${remote} ttl 255 ip addr add 172.16.1.1/24 peer 172.16.1.21 dev ${dev} ip link set ${dev} up ip route add ${network} dev ${dev} And ip l: 14: gre21: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN link/gre 0.0.0.0 peer 109.60.170.15 How to set state "running"? How to keep alive tunnel? Ping in cron?

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  • richfaces keepAlive not working

    - by Jurgen H
    I have a mediaOutput tag which, in its createContent attribute, requires the backing bean to be in a certain state. A list of values, which is filled in an init method, must be available. I therefore added a keepAlive tag for the whole backing bean. I now indeed see the backingBean in stead of some (richfaces) proxy bean, but the filled list is null again. How to make this possible? I checked that the init method was called and that the list is filled in in the init method. <a4j:keepAlive beanName="myBean" /> <a4j:mediaOutput createContent="#{myBean.writeChart}" ... /> The backing bean public class MyBean implements Serializable { public List list; public void init(ActionEvent event) { // call some resource to fill the list list = service.getItems(); } public void writeChart(final OutputStream out, final Object data) throws IOException { // list is null } // getters & setters }

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  • Keeping rackspace vserver alive

    - by mit
    It appears to me that rackspace somehow freezes cloud VMs after some idle time. This means the first page request to a php page takes much longer to respond than the subsequent requests. This is in some cases good, in other cases not acceptable. I am actually querying a machine with wget from a different host now to keep it "alive". But I wonder what frequency would be necessary. Does anyone know the time period after which they send a VM to "sleep"? I guess it would be some minutes. EDIT: There is absolutely no caching involved on the php site. It just recently moved from another vhost and there was never such latency on the first request.

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  • Scriptable FTPS client able to send Keep Alive to control port?

    - by schultkl
    We need a FTP client that satisfies the following constraints: Windows Command-line scriptable, so we can automate it...sorry, FileZilla (?) FTPS, as it seems to perform better than SFTP The ability to send KeepAlive commands to the FTPS control port No passwords sent on the command line...sorry, curl Number 4, above, is critical: we have set KeepAlive in some other clients (e.g., CoreFTP LE) but we seem to have some routing equipment in the server environment which drops our connection when transferring a 7GB+ file. We have also set passive mode and "resume transfer" functionality seems currently broken with this secure file transport server...so we need to download the file in one go. What FTPS clients might meet our needs?

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  • Should `keepalive_timeout` be removed from Nginx config?

    - by Bryson
    Which is the better configuration/optimization: to explicitly limit the keepalive_timeout or to allow Nginx to kill keepalive connections on its own? I have seen two conflicting recommendations regarding the keepalive_timeout directive for Nginx. They are as follows: # How long to allow each connection to stay idle; longer values are better # for each individual client, particularly for SSL, but means that worker # connections are tied up longer. (Default: 65) keepalive_timeout 20; and # You should remove keepalive_timeout from your formula. # Nginx closes keepalive connections when the # worker_connections limit is reached. The Nginx documentation for keepalive_timeout makes no mention of the automatic killing, and I have only seen this recommendation once, but it intrigues me. This server serves exclusively TLS-secured connections, and all non-encrypted connections are immediately rerouted to the https:// version of the same URL.

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  • Is this normal? Multiple httpd process

    - by ilcreatore
    I'm testing a new Server. This isnt really a peak time for my server (2pm), but still its running a bit slow, I was checking the ESTABLISHED connections using the following command: # netstat -ntu | grep :80 | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n http://i.stack.imgur.com/cZuvP.jpg My MaxClients are set to 50. So as you can see on the picture, only 10 people are eating most of my ram. I got a server with 4GB Ram (2.7GB free for apache) but each apache process is eating 53MB each, wich mean im only allowed to accept 50 process. The KeepAlive = Off, but I notice those connections arent closing fast enough, is that normal?

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  • Why would you ever set MaxKeepAliveRequests to anything but unlimited?

    - by Jonathon Reinhart
    Apache's KeepAliveTimeout exists to close a keep-alive connection if a new request is not issued within a given period of time. Provided the user does not close his browser/tab, this timeout (usually 5-15 seconds) is what eventually closes most keep-alive connections, and prevents server resources from being wasted by holding on to connections indefinitely. Now the MaxKeepAliveRequests directive puts a limit on the number of HTTP requests that a single TCP connection (left open due to KeepAlive) will serve. Setting this to 0 means an unlimited number of requests are allowed. Why would you ever set this to anything but "unlimited"? Provided a client is still actively making requests, what harm is there in letting them happen on the same keep-alive connection? Once the limit is reached, the requests still come in, just on a new connection. The way I see it, there is no point in ever limiting this. What am I missing?

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  • Keep-Alive header not sent from Tomcat 5.5 http connector?

    - by Codek
    Hi, We're currently using a hardware load balancer, which then goes to Apache and that then goes to Tomcat 5.5 via the AJP connector. We've decided to dump apache for various reasons - In our current system it doesnt provide any advantage. However when I look at the headers sent when we do this, the "Keep-Alive: timeout=15 max=96" header doesnt get sent when you use the tomcat http connector Interestingly, i can find no documentiation on "keepalivetimeout" for tomcat5.5, but i can for tomcat6. But neither can i find evidence that tomcat5.5 doesnt support this setting. here's my connector: <Connector port="8090" maxHttpHeaderSize="8192" maxThreads="400" minSpareThreads="150" maxSpareThreads="300" enableLookups="false" connectionTimeout="2" maxKeepAliveRequests="400" disableUploadTimeout="true" /> So; Is there any way I can specify the keepalive timeout if we use the http connector with tomcat 5.5, and force this header entry to be sent? Thanks, Dan

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  • Funnelling http traffic

    - by spencer p
    I have a situation where a large batch of servers (X), on demand, need to request data from a smaller set of web servers (Y). The worst case scenario is if all servers in X decide to fetch different requests to one server in Y. That would be X amount of connections, which could be a very large burst of traffic. The best case scenario is if 1 server in X hit 1 server in Y in tandem. Life does not work like this. One idea to entertain is placing a proxy, similar to squid between X and Y. All of X servers can connect to this proxy, but would result in a few persistent (http keepalive) connections to Y. If The few were say, 3 or 4, then it would funnel. If we could then rate limit those connections and traffic decides to spike unusually high, we wouldn't hurt anyone but ourselves. Thoughts?

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  • Spawning HTTPD processes

    - by felix001
    Can any confirm how Apache spawns new children ? As in if I connect to a webserver (HTTP 1.0 / no keep alive) and issue a HTTP /GET I will be spawned a new HTTPD child. If then issue another HTTP /GET then a new TCP connection will be built. However will I use the same child process of would I spawn a new one ? Also if I was using HTTP 1.1 (with keep-alive) and reused the same TCP connection, would the httpd process/spawning be any different to that if I wasnt using keepalive ? Thanks,

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  • Can I force Apache 2.2 connection close from inside a C module?

    - by Amos Shapira
    Hello, We'd like to have a more fine-grained control on the connections we serve in a C++ Apache 2.2 module (on CentOS 5). One of the connections needs to stay alive for a few multiple requests, so we set "KeepAlive" to "On" and set a short keep-alive period. But for every such connection we have a few more connections from the browser which we don't need to leave behind and instead want to force them to close after a single request. Some of these connections are on different ports (so we can distinguish them by port, since KeepAlive can be set per virtual host) and some request a different URL (so we can tell from the path and parameters that we don't want to leave them behind). Also for the one we do want to keep alive, we know that after a certain request we'd like to close it too. But so far the only way we found to "cancel" the keep-alive is to send a polite "Connection: close" header to the client. If the client is not well behaved, or malicious, then they can keep it open and waste our resources. Is there a way to tell Apache to close the connection from the server side? The documentation advises against just plain close(2) call on the socket since Apache needs to do some clean up before that's done. But is there some API or a trick to "override" the static "KeepAlive On" configuration dynamically (and convince Apache to call close(2))? Thanks.

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  • Keep-Alive header not sent from Tomcat 5.5 http connector?

    - by Codek
    We're currently using a hardware load balancer, which then goes to Apache and that then goes to Tomcat 5.5 via the AJP connector. We've decided to dump apache for various reasons - In our current system it doesnt provide any advantage. However when I look at the headers sent when we do this, the "Keep-Alive: timeout=15 max=96" header doesnt get sent when you use the tomcat http connector Interestingly, i can find no documentiation on "keepalivetimeout" for tomcat5.5, but i can for tomcat6. But neither can i find evidence that tomcat5.5 doesnt support this setting. here's my connector: <Connector port="8090" maxHttpHeaderSize="8192" maxThreads="400" minSpareThreads="150" maxSpareThreads="300" enableLookups="false" connectionTimeout="2" maxKeepAliveRequests="400" disableUploadTimeout="true" /> So; Is there any way I can specify the keepalive timeout if we use the http connector with tomcat 5.5, and force this header entry to be sent? Just to be clear - the exact header entry i see back from the server is this with apache: Keep-Alive: timeout=2, max=100 But nothing from tomcat/coyote. I've looked at this some more, and I dont think the Keep-Alive header entry really matters. The problem seems to be that keep-alives are simply not supported in tomcat 5.5 http connector? They do seem to work in tomcat6 (+java 6). Thanks, Dan

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  • Apache MaxClients doubt

    - by Milan Babuškov
    I have a busy Apache server serving only dynamic PHP+MySQL pages. It is a prefork Apache, version 2.2.4 with following config: KeepAlive off StartServers 8 MinSpareServers 32 MaxSpareServers 64 ServerLimit 512 MaxClients 512 MaxRequestsPerChild 4000 MaxClients/ServerLimit used to be set to 256, but I got the following error in error_log so I increased it: [error] server reached MaxClients setting, consider raising the MaxClients setting It seems to work now, but I have a doubt. Looking at MySQL log of queries, I have a couple hundred clients per seconds, but "ps ax" only shows 8, 9 or 10 processes running: [root@engine ~]# ps ax | grep http | wc -l 10 I even got this many processes when the above error message was shown in error_log. This made me investigate further. When I run netstat -a, I get something like this: tcp 0 0 engine:http adsl-105-143.teol.net:21453 TIME_WAIT tcp 0 0 engine:http 118-36.static.kds:mck-ivpip TIME_WAIT tcp 0 0 engine:http 118-36.static:oce-snmp-trap TIME_WAIT tcp 0 0 engine:http 118-36.static.kd:unifyadmin TIME_WAIT tcp 0 0 engine:http cable-188-2-25-29.dyna:4906 TIME_WAIT tcp 0 0 engine:http adsl-105-143.teol.net:21458 TIME_WAIT tcp 0 0 engine:http 109-92-83-91.dynamic.:62821 TIME_WAIT tcp 0 0 engine:http cable-89-216-142-192.:63576 TIME_WAIT tcp 0 0 engine:http 109-92-83-91.dynamic.:62819 TIME_WAIT tcp 1081 0 engine:http pttnetadsl38-36.ptt.r:50496 ESTABLISHED tcp 0 0 engine:http cable-188-2-36-196.dyn:4136 TIME_WAIT tcp 0 0 engine:http cable-89-216-142-192.:63580 TIME_WAIT tcp 0 0 engine:http cable-89-216-142-192.:63581 TIME_WAIT etc. When counting those, I get: [root@engine ~]# netstat -a | grep http | wc -l 431 Can anyone tell me what is really going on here and how to make sure my server keeps working, because I only use 50% of available RAM in machine?

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  • How to know the source of certain TCP traffic on AIX

    - by A.Rashad
    We have two AIX boxes, one for production system and another for testing. both systems are running ATM machine switches, where the ATM device is connected via TCP socket. we had an issue on production system where the machine would power off or get disconnected but the netstat -na | grep <IP of machine > would still mention that the socket is up when simulated that case on the UAT environment, the problem did not happen, where the socket would terminate in 3 to 5 minutes. when sniffed on the traffic between the machine and ATM we found that no traffic takes place on production while there is some sort of heartbeat on UAT. but it is not initiated by the application. $>tcpdump | grep -v "10.2.2.71" | grep -v "HSRP" | grep "10.3.1.30" tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on en6, link-type 1, capture size 96 bytes 09:08:13.323421 IP server073.afs3-callback > 10.3.1.30.impera: . 278204201:278204202(1) ack 3307884029 win 164 09:08:13.335334 IP 10.3.1.30.impera > server073.afs3-callback: . ack 1 win 64180 09:08:23.425771 IP 10.3.1.30.impera > server073.afs3-callback: . 1:2(1) ack 1 win 64180 09:08:23.425789 IP server073.afs3-callback > 10.3.1.30.impera: . ack 2 win 65535 09:09:13.628985 IP server073.afs3-callback > 10.3.1.30.impera: . 0:1(1) ack 1 win 164 09:09:13.633900 IP 10.3.1.30.impera > server073.afs3-callback: . ack 1 win 64180 09:09:23.373634 IP 10.3.1.30.impera > server073.afs3-callback: . 1:2(1) ack 1 win 64180 09:09:23.373647 IP server073.afs3-callback > 10.3.1.30.impera: . ack 2 win 65535 while on production, that traffic is not there. we want to know where this traffic is initiated from to implement on production to sense disconnection our comms parameters are: tcp_keepcnt = 2 tcp_keepidle = 100 tcp_keepinit = 150 tcp_keepintvl = 150 tcp_finwait2 = 1200 can anyone help? Editing Question: One point I missed because I was rushing to a meeting. the difference between the Production and UAT in setup is that in Production we have an application called F5 working as load balancer between the ATMs and the AIX box, while it is a direct connection through MPLS in case of UAT. note: we had one MPLS and one GPRS connected ATMs on UAT, and both connections terminated when unplugged in about 4 minutes Edit 2 the no -o tcp_timewait command returns 1 in both Production and UAT

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  • Why aren't connections released by the tomcat AJP connector

    - by Chris
    I have here a jboss with a web application. The tomcat is configured to use the ajp connector. Incoming connections are tunneled via an apache reverse proxy to the connector. Now I recognized that under heavy load the connector keeps a bunch of connections in "keep alive" mode for eternity and doesn't release them any more. With the normal HTTP connector the app did well, but now with the ajp connector we have regular app stallments. Can someone give me some advice where to start to look to resolve this issue? Why does the connector not release the connection again after idling for 300 secs? thanks, chris

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