Networking :: What Could Be Causing SYN_ACK's To Be Delayed From Certain Clients
Feb 18, 2010
I'm having a problem with TCP connections taking a long time to establish, often timing out. The strange thing is it seems to only happen on some source workstations and not others in our LAN but not from home or other internet connections.I can see the SYN packet leave the source workstation, enter the firewall LAN interface, leave the firewall WAN interface and arrive at the destination server's interface. Then the SYN ACK packet doesn't get sent for 2 to 300 seconds. Once I see the SYN ACK sent from the server, the connection is ESTABLISHED.
I'm running Fedora 10 on a HP Compaq 6710b laptop. It is by far the best OS I have ever used and have no complaints, but I seem to be having some trouble with the wireless at work. The office has a single Cisco Aironet 1131 configured for WPA2 using AES with a PSK. The SSID is not broadcast. The mode is B/G mixed. My wireless card is a built-in Intel PRO 3945ABG, the driver is IWL3945 (auto configured during the OS install).
I use the Network Manager to manually add my SSID and select "WPA & WPA2 Personal" on the security tab and enter the PSK in the password field. After a few moments the wireless connects and appears to be working fine. About every 3-5 minutes while using the office network I get the "kernel error" dialog in the bottom right hand corner of my screen and the wireless drops connection. It re connects after about 30 seconds and appears to work fine until the next kernel error.
I got a new X201 which is running Ubuntu 10.04. While at home, everything is fine, at work, I encounter some issues with wireless. the signal cuts in and out repeatedly.Here's the output of ping. I set it to ping a server every 90 seconds, 10 times. So this is a snapshot of 15 minutes of network activity...
Code:
PING (REDACTED) bytes of data. 64 bytes from (REDACTED): icmp_seq=1 ttl=252 time=1.50 ms 64 bytes from (REDACTED): icmp_seq=2 ttl=252 time=2.13 ms 64 bytes from (REDACTED): icmp_seq=3 ttl=252 time=1.38 ms
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Also I tried this (from a 2 year old thread which was most relevant solution I could find):
Code:
Changing AVAHI_DAEMON_DETECT_LOCAL=1 to AVAHI_DAEMON_DETECT_LOCAL=0 in /etc/default/avahi-daemon has got rid of the irritating pop-up. Basically, every 5 minutes or so, for a solid 60 seconds or so I get no signal. I've tried updating the kernel, and doing apt-get remove avant-daemon, but still have problems.
I'm running Ubuntu 11.04 and I'm really new to linux. My problem is that whenever I try to browse a site I notice the website loads very slowly because it takes a long time to do lookups. I installed Ubuntu with an onboard NIC and later switched to a PCI NIC (Dlink DGE-530T). Although I disabled the onboard NIC in the BIOS, it doesn't help. Could this conflict in configuration be a problem? My download rates are fine, its just lookups that take really long ( upto ~ 10 seconds). I know the PCI network card is fine because when I jump to Windows 7, lookups are normal again (~ 300ms). At first I thought about installing the sk98lin drivers for the PCI NIC but I saw a couple of places where people have mentioned that the skge driver that comes along with the kernel is better.
I have tried a system wide as well as Firefox disable of IPv6. Here is my /etc/udev/rules.d/70-persistent-net.rules Code: # PCI device 0x1186:0x4b01 (skge) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:24:01:14:eb:39", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0" # PCI device 0x10de:0x0373 (forcedeth) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:1e:8c:3e:19:ed", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1" The interface I want to use according to the listing above is the one with the MAC - 00:24:01:14:eb:39.
I tried removing one of the entries in the file above and rebooting but it still didn't work. Here is a look at my /etc/network/interfaces Code: auto lo iface lo inet loopback # The primary network interface auto eth0 iface eth0 inet static address 192.168.1.10 gateway 192.168.1.1 netmask 255.255.255.0 network 192.168.1.0 broadcast 192.168.1.255
We have an old Zonet 10/100 switch in our home network that locks up whenever there's a power glitch longer than about a microsecond. (OK. It's not that bad but if the lights flicker, I usually end up going down to the basement to see if the switch is hung.) None of the computers or peripherals are affected by the glitches, BTW. Power-cycle the switch and everything starts working again. After putting up with this for months I finally picked up a Netgear 8-port 10/100/1000 switch to replace the Zonet. Unfortunately, when the Netgear switch is in the network, everything slows to a crawl before completely freezing up. Pinging other systems barely worksname would not work.Pinging another system by its IP address worked a little but packet losses of 70%-80% were the best I saw. At first. Then it gets to where the loss is 100%.
All systems were rebooted after the Netgear switch was inserted into the network. The systems that were capable of gigabit connections autosensed the new switch and set their port speed accordingly. And that's about all that works when the Netgear switch is present. (The Zonet is back in the network now.)One thing I have not tried is forcing the port speed on the gigabit-capable systems to 100Mb and re-inserting the Netgear switch into the network to see if the problem if due to running some of the ports at 1000Mb.The systems on the network are running various versions of Linux (with different kernel versions, of course). Most are due for upgrades to get them current but I was planning on hitting the systems that had gigabit-capable ethernet interfaces thinking that a.) 100Mb speeds have been around forever and no problems have been seen when everything was running at 100Mb in the past and b.) the gigabit support for the older kernels should be better (one system only supports an MTA of 1500 max at 1000Mb).
So I have recently been making attempts at setting up my RTL8192SU chipset usb wifi. After struggling to set it up by following the steps on this link: [URL]../url?sa=t&jUyXQukrfIw After doing this I had no idea what it was supposed to look like but It did display several warnings along the lines of "warning: cast from pointer to integer of different size" I continued following steps as another error occurred "cp cannot stat autoconf.rtl8712_usb_linux.h" I then entered sudo modprobe 8712u and my screen went black i was forced shut down . Upon rebooting I found it also would lock up if my usb device was plugged in It will boot with it unplugged but as soon as it is plugged in again it will lock up my system and send it to a black screen.
I noticed this weekend that I began experiencing wireless issues with the NIC (Intel 5300) on my laptop. I have had no problems with the wireless using several Ubuntu versions. This began after I installed the packages associated with the Update Manager last Friday, which included the 2.6.32-25.43 kernel update. My wireless will drop out anywhere from 10 seconds to a couple minutes later after connecting to my router. Again, I have not have any wireless issues before. Below is the end of dmesg when I enable the device.
[ 1220.725229] Registered led device: iwl-phy0::radio [ 1220.725372] Registered led device: iwl-phy0::assoc [ 1220.725883] Registered led device: iwl-phy0::RX [ 1220.726422] Registered led device: iwl-phy0::TX [ 1220.749395] ADDRCONF(NETDEV_UP): wlan1: link is not ready [ 1228.969542] wlan1: deauthenticating from 00:24:01:f5:b8:b0 by local choice (reason=3) [ 1229.008433] wlan1: direct probe to AP 00:24:01:f5:b8:b0 (try 1) [Code].....
I bought an RTL8187L USB wireless adapter, and have had trouble getting it to work. I have managed to get it to work via manually configuringtime, but lost that configuration, and now it is once again not workingThe root issue appears to be (if I'm understanding correctly what I'm seeing) that when I connect, routes don't get setup properly, so when network manager (or WICD, which I've also tried) get to the DHCP step, my wireless router can't be reached by dhclient.
This is on Ubuntu 9.10, and I'm using the updated driver from realtek.com, btw, though the in-kernel driver was exhibiting the same behavior.So, two questions:- Is anyone familiar with this problem, and is there a fix available?- I believe I can work around it by setting up routes manually (e.g. with a post-connect script in WICD), but after staring at the "route" manpage, I'm not 100% sure of the commands. My router (a FIOS MI424WR) is my DHCP server, and is at 192.168.1.1, and route -n on a working PC (wired connection) gives:
Code: dave@MinasTirith:~$ route -n Kernel IP routing table
I need to set up a VPN between 2 clients but don't have the foggiest idea where to start. I have searched the internet in vain, I have yet to discover the steps I need to take.
Ok, here goes, I have a rdp server sitting at a remote store which is behind a router I do not control.
I might be able to get the phone company to add routing to it but at the moment I'd like to do this with ssh and reverse port routing, because I might need this for other ports later and I never know if the phone company wont break other routings already in place or just screw up the entire thing .
I am able to have a linux box at the site ssh into a server located where I'm at and reverse port forward port 3389 to that server. I can also then ssh into that server from my linux box and port forward 3389 to my box, under another port since my 3389 is already in use. Finally I can use rdesktop to rdp on the my local box which bounces it through the server and back to the linux box which forwards it to the rdp server (A Windows 2008 server to be exact). This is all well and good and works reasonably fast, but, I need to be able to have users on windows boxes at my site do this without all of the rigmarole. I need to, I guess, redirect a normal open port, or create one, on the server where I am so that it connects internally to the reverse forwarded port or open the internal port to the outside. So I guess I need to make it a 'gateway' for that one port, this way all I have to do is point the rdp clients at the main server and port to have it eventually connect to the rdp server in the remote store.
how to go about doing it. I guess I need an iptables entry forwarding the port but I'm not sure what is should be.
The other option is opening up the port 3389 to the outside but I'm not sure how to do that either. Right now I have no iptables entries at all but even if I turn off iptables completely port 3389 is not available if I try to use it from another pc on the network but I can rdp from the server itself using the 3389 port so I know it's working internally.
I have a client in Pittsburgh that has a Mac server and a Linux (RHEL) server on a LAN. They have a Netgear FVS 318v3 router on which they had a VPN running. They could do this because they had the router configured for IP-SEC and they only had Mac laptops as clients. I'm told Mac laptops can be configured to connect to IP-SEC VPNs, but Linux (I have Ubuntu) clients cannot.
I'm told that we need an PPTP VPN, and that the Netgear can not act as an endpoint, but can pass PPTP traffic to one of the servers if we set them up as a PPTP server.
We hired two different network consultants to set up the VPN, but neither one is able to set up a VPN to allow both the Mac and Linux laptops to connect.
Why is this so difficult? Lots of companies have VPNs that allow any client to connect.
Would it be better for us to purchase a different router that can act as a PPTP endpoint?
Do I want the router to act as a PPTP endpoint, or would it be better for me to use the Netgear and set up a PPTP service on one of the servers? Or, is there some better solution?
I'll state the issue and then give whatever extra details are needed. I'm running Ubuntu 10.xThe Linux box is connected to a router via ethernet. That Linksys router is bridged to an AT&T router.The bridging is working fine. The AT&T router's page shows the IP of the Linux box and lists it as a device. The Linksys page shows no errors with packet transmission and receipt. I can ping the Linux box from any client on the AT&T router, and can ping the AT&T clients from the Linux boxI had set the IP of the Linux box to192.168.1.201 while configuring that router, as I had set that router to 192.168.1.200 and it just seemed orderly.The network preferences show eth0 being set to auto dhcp, but the IP is still set to .201 so I don't know that it actually released or renewed.
Were seeing very strange problems related to Alteon and linux clients. We got an Alteon Application Switch 2208(Version 22.0.2) balancing traffic for http, https and ldap. Everything works fine when using windows(iexplorer) or RHEL 5.3 clients, as wget, firefox, or direct telnel to por 80 or 389. But we got some linux machines, a CENTOS 5.5 for example, that can�t make it to work. No special configuration, no different vlans or subnets. It just stay waiting for the response:
The Server in the above diagram can be accessed by Client3 and Client4 but not at all by Client1 or Client2. Router0 specifies the Server as a DMZ Host. I would be more specific but this is not my server. I don't use a DMZ, I forward ports when they are needed. In this case I represent ISP1 and the server belongs to a befuddled client. Client1 & Client2 can send packets to each other, no problem. Could the DMZ be breaking communication between the Server and Clients 1 & 2?
I'm having a problem getting X to forward from one of my machines on my network. There are a bunch of clients running RHEL5 and one server also running RHEL5. When I ssh from any client to any of the other clients using: ssh login@client3.blah.blah.blah -X everything works fine, but if I try to ssh to the server ssh login@server.blah.blah.blah -X
I get the following error: emacs: Cannot connect to X server localhost:10.0. Check the DISPLAY environment variable or use `-d'. Also use the `xhost' program to verify that it is set to permit connections from your machine. I've also tried from my mac laptop to ssh with -X to both my client machines and the server, with the same problem. Forwarding works fine when I ssh to the clients, but not to the server.
Things I've done/tried: I've checked sshd_config for X11Forwarding yes. I also tried adding the server using xhosts. Turned off all firewalls. It really seems to be a problem with my server since I have the same problem with my mac laptop (on a totally different network).
is there a way to configure shutdown on critically low battery to give me a bit of time before actually shutting down?I've set Gnome to shutdown on low battery. Problem is, I don't get any notification about battery running low, and as soon as battery level reaches the critical threshold, the system starts shutdown without me having any possibility to quickly complete some tasks. Of course, I'd increase battery level thresholds accordingly.
I have openSUSE 11.3 on my Lenovo Thinkpad X61. It has been running fine for many months, but yesterdaychanged. For example, between the two previous words I had actually typed "something" ("yesterday something changed") but it was lost. I type at normal speed but the machine cannot keep up. Hopelessly annoying. This happens in every application I have checked. The only unusual thing I did yesterday was to load a bunch of photos off a relative's digital camera. I'm concerned I may have picked up spyware.
When I reboot, USB keyboard acts just fine for GRUB. Once SUSE begins to boot, I lose the keyboard (numlock light goes off too). Cannot press ESC to watch the boot sequence. Then, at login, there is no mouse or keyboard for about 60 seconds. Then suddenly, they both become active. Why did this start happening?
It has been about a week since my last reboot, so there's been a few config changes and patches, so it's going to be hard to narrow down a culprit. Thought USB configs in /etc/fstab was the problem, but still happening after rolling back changes to a known good config. Re-ran SaX2. Mouse and keyboard look good in the config file. Also, have otherwise healthy USB behavior with thumb drives and in VirtualBox machines. It just acts goofy at boot time.
way to hibernate at a specific time or after a some minutes (like 40 minutes to an hour, guess the exact time doesnt matter anyway). normally i shutdown my comp at night with
Code: sudo shutdown - P HH:MM
which works just fine, but sometimes i have like 4 workspaces of stuff open that i'm working on so i'd rather just hibernate. shutdown -H does this halt thing that is really not my cup of tea so from the aformentioned googling i found out about at and sleep and crontab etc. but at and sleep cant recieve my sudo password beforehand so its useless and crontab is for repetitive scheduling, which i'd like to avoid cause i would hate to be working and suddenly have my forgotten crontab script hibernate me.
so is there any way to do a delayed hibernation? or at least some way to provide the sudo password to an at or sleep prefixed command, beforehand?
i'm only interested in doing it straight up through the terminal, not through other 3rd party software cause i tried a few of those before i found out about shutdown and they didnt work very well.
I have a script running at the moment via cron which takes a picture every minute from my webcam. gst-launch-0.10 v4l2src num-buffers=1 ! jpegenc quality=95 ! filesink location=/home/user/$picture.jpg However, the camera is only on for one second and takes the picture which leads to very dark images as the light sensor hasn't had a chance to work yet. However, if I load up Cheese, it brightens after about 10 seconds of the camera being on. Is there anyway of adding in a delay to the pipeline above so the camera stays on for 10 seconds before actually saving the file to a jpg?
I'm setting up a network for a school. The network has 11 client computers (windows xp) and a server (fedora 10) All I need to do is have a share for all the children to use. (this I did by adding each client to the workgroup specified on samba then I just map the drive). The issue turns out to be that I have over 300 users. The users don't always use the same computer therefore I need the users to be registered on all 11 clients. How can I do this? I have been searching and I've not gotten anywhere. How can I add the computers to a domain instead of a workgroup? What can I use?
I'm trying to get a pptp server up and running. The server starts just fine, but encounters errors when a client tries to connect.
Code:
CTRL: I wrote 32 bytes to the client. Dec 29 23:27:48 frankenstein pptpd[9402]: CTRL: Sent packet to client Dec 29 23:27:48 frankenstein pptpd[9403]: CTRL (PPPD Launcher): program binary = /usr/sbin/pppd
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I assume the failed read line is the culprit. I am currently running on a test machine. There is no firewall. I read on this error points to a firewall misconfiguration, but there isn't one.
That is, the thin clients will have to get their OS image via TFTP, and their IP address via DHCP on a *wireless card* - is this possible?What spec should I ask for/search for when buying the WiFi card?
having trouble connecting to many websites due to recent actions of the Iranian government on banning a lot of websites.That's why, I decided to make my computer act like a bridge for their computers, so that they can surf the web using my Internet connection in US. I have Arch linux running on my desktop. I tried to install OpenVPN based on the instructions at ArchWiki page, but I had no success. I guess OpenVPN is too much for what I want to achieve and ArchLinux repositories don't have all the necessary packages to configure it based on some posts I read.
Im a linux newbie and I'm some sort of creating an Internal webserver or Intranet for short locally. My local webserver ip address is 192.168.0.1 and when im trying to view this on my xp clients i will type it in the url 192.168.0.1. What im trying to do is view my webserver instead of typing ipaddress I'll type hmij.edu.ph for example and trying to resolve it locally through local dns resolution.. so every time i type for example. my webserver name hmij.edu.ph i want it to redirect it to my local webserver w/out going to the internet first.. I already setup dnsmasq for dhcp and dnsclient resolution. is there any better way on how i can achieved this??im a little bit of confused on how to make this work. tnx in advance!
I have been running Senmail on SuSE 11.1 for the last few years with no problems.Since installing SuSE 11.3 a few months ago I have been having problems getting Sendmail to send to some (only a few) servers.If I disable the firewall # SuSEFirewall2 stop.I can send successfully using # sendmail -v -q, or # sendmail -v -qIxxxxx.When I re-enable the firewall I will start to get the timeouts/temporarily unavailable messages again (but as mentioned above, only for some servers) even though I can successfully telnet these servers when the firewall is on. When I disable the firewall the delayed messages can again be sent.Has anybody any ideas what I need to change (presumably in the Firewall) to get things working correctly? 'SMTP with sendmail' is already selected under 'Services to Allow' under YaST Firewall->Allowed Services..
