Networking :: See The Number Of Packets Dropped By Kernel Due To Insufficient Queue Size?
Sep 15, 2010
As is known, there is a queue lies between the kernel subsystem and the network driver for incoming data. And if data come when this queue has no space for it, the data got dropped by kernel. Is there some way to see how many packets are dropped due to this buff penury? I tried netstat -s but could not find something useful. On the other hand, I found this 12176 packets collapsed in receive queue due to low socket buffer from netstat -s. I think this is something related to the per-socket buffer, but not the incoming queue between the network driver and kernel. Is this right?
View 1 Replies
ADVERTISEMENT
Oct 1, 2010
One of our RHEL 5.3 servers has trouble about 30% of the time with TCP-based communications, but it does not seem to be firewall issues. From another computer on the same switch, you can SSH to the server sometimes and other times the SSH command will just hang. When it hangs, you can often just Ctrl+C and try it again and it works. Same with HTTP connections. You'll get part of a web page and then FireFox will just hang waiting for the rest and eventually time out. Same goes for communication initiated FROM the server. SSH'ing from the server to any outside server or connecting to any web site works sometimes, but most times not. iptables if off. No other firewalls are running. Tcpdump shows communication gets so far and then stops. It does not matter whether tou run tcpdump on that server or the client connecting to it. Either way you see the connection stops working. MEANWHILE, pinging with small or large packets works flawlessly. 10,000 packets, zero drops.
View 5 Replies
View Related
Jan 11, 2010
I've recently installed Ubunter 9.10 Server Edition to use as a NAT firewall for the lab I run. I'm using iptables to do NAT forwarding and everything works great except that, occasionally, connections seem to break. Ssh connections close with "Connection reset by peer" and HTTP connections just stall out.I believe this has to do with the firewall's internal network interface occasionally dropping packets.
View 2 Replies
View Related
Feb 13, 2009
I have question regarding netstat? When performing a "netstat -s" I receive the following information regarding dropped packets under IP:
IP:
93978695 total packets received
0 forwarded
0 incoming packets discarded
79472157 incoming packets delivered
65235033 requests sent out
29527 outgoing packets dropped
However if I run a "netstat -i" I have no dropped packets whatsoever: (apologies for the table format):
Kernel Interface table
Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
bond0 1500 0 34326528 0 0 0 72755307 0 0 0 BMmRU
bond0:1 1500 0 - no statistics available - BMmRU
bond1 1500 0 28605491 0 0 0 20948952 0 0 0 BMmRU
eth0 1500 0 34199550 0 0 0 72755278 0 0 0 BMsRU
eth1 1500 0 126978 0 0 0 29 0 0 0 BMsRU
eth2 1500 0 97911 0 0 0 1 0 0 0 BMsRU
eth3 1500 0 28507580 0 0 0 20948951 0 0 0 BMsRU
lo 16436 0 34094225 0 0 0 34094225 0 0 0 LRU
View 5 Replies
View Related
Mar 13, 2010
I am using ubuntu 9.10. Configuring my firewall using guarddog. I have setup a rule to allow traffic OUT on port 7078 UDP, and just because i'm having problems i added an IN rule.
# Create the filter chains
# Create chain to filter traffic going from 'Internet' to 'Local'
ipchains -N f0to1
[code]....
View 2 Replies
View Related
Dec 5, 2010
I've run into a of a routing issue pertaining to packets leaving a firewall, traversing and IPSec tunnel, hitting the target and then returning via a different tunnel, finally arriving back on the source firewall but on a different interface from where it started. Once the packet has returned to the firewall it is dropped I've been unable to discover the reason for the drop. Two sides to the system, Firewall A and Firewall B. Each firewall provides the default gateway to its respective side and offers a backup IPSec tunnel to the high capacity tunnel handled internally. The Layer 3 Switch uses OSPF and takes care of the bulk of the behind the scenes routing between the sides. In case of failure the Layer 3 switches direct traffic to use the Firewall tunnels to route traffic.
View 2 Replies
View Related
Apr 4, 2011
I'm running a Debian Squeeze 6.0.1a box that's connected to my ISP via an L2TP connection that's managed by OpenL2TPD. The box is configured to perform NAT from local clients (on eth0) to the internet (on ppp0).
However, I'm having an issue with TCP packets that are sent from the box itself to the internet (packets originally coming from the local clients get sent and received over the internet just fine)
I'm using this Python app to test this:
Code:
#!/usr/bin/env python
import socket, time
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('', 5003))
s.listen(1)
while 1:
conn, addr = s.accept()
[Code]...
View 3 Replies
View Related
Oct 5, 2010
In my Fedora13 machine, while in mobile broadband, i can ping and skype outside, but cannot browse/yum etc. Few output that may be of relevence are here:
$ netstat -s
IP:
149468 total packets received
6 with invalid headers
16174 with invalid addresses
0 forwarded
0 incoming packets discarded
118821 incoming packets delivered
101331 requests sent out
124 outgoing packets dropped
866 dropped because of missing route .....
View 3 Replies
View Related
Feb 28, 2010
with my other ethernet card problem solved, I suddenly run into this:
Code:
eth1
Link encap:Ethernet HWaddr 00:02:e3:16:37:4c
inet addr:10.0.2.1 Bcast:10.0.2.255 Mask:255.255.255.0
inet6 addr: fe80::202:e3ff:fe16:374c/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
[Code]...
This card was working perfectly fine up until....an hour ago and it started doing this. My iptables isn't blocking it somehow, because I didn't change anything. I tried reverting to an older kernel and that didn't help. It's not the network cable, it works fine in any other card. Also, the dropped packets seem to count down? It seems to go down by exactly one every time I run ifconfig, no matter the length of time in between running it.
View 3 Replies
View Related
Oct 18, 2010
I am trying to figure out what command to use to show the number of DROPPED and INVALID packets that the firewall is handling.I'm going to put these commands into a log analyzer script which will run every 15 minutes with cron. The firewall is running and operating the way I want it to. I'm running CentOS 5.4.
View 2 Replies
View Related
Jul 9, 2010
In my Solaris tcp client server program, In server side I am checking the size of recv buffer, based on different listen queue size.
I was expecting this size to be increased due to the increase in receive queue size. why the value is same ?
View 1 Replies
View Related
Aug 9, 2010
I'm looking for an open source/free network emulator tool that I could use on Mac OS X, to simulate a slow network connection, limited bandwidth and other network characteristics such as dropped packets etc for both UDP/TCP connections (or even on the physical layer).
I'm looking for the simplest solution that would allow me to run TCP/UDP servers and have a few clients connect to them on localhost emulating various network connections. I'm mainly wondering if I can use something like Linux's netem on Mac OS X (or even better cross-platform Windows/Linux/Mac). Perhaps I can run VirtualBox and a Linux kernel running netem, has anyone had luck with that?[URL]...
View 2 Replies
View Related
Sep 12, 2010
I've been receiving a LOT of log cruft ever since I installed my WUSB100V2 (using the rt2870sta community driver from the Linux kernel) and was wondering what it all meant.
Many times when these messages occur it is accompanied by slow network speeds and many DNS queries and outgoing SYNs being dropped. I have searched for documentation for these (error?) messages and have come up empty as far as what they mean or how I can stop them from occurring.
I reside on the opposite side of the building from my WAP. I have taken steps to improve the signal strength, but the signal quality hovers between 50% and 70%, sometimes dropping to 40% for unknown reasons.
My /var/log/messages:
Sep 12 05:04:40 necronomicon -- MARK --
Sep 12 05:29:48 necronomicon kernel: 0:3 LTL=0 , TL=0 L:4284
Sep 12 05:29:53 necronomicon kernel: 0:3 LTL=0 , TL=0 L:4104
Sep 12 05:30:06 necronomicon kernel: 0:3 LTL=0 , TL=0 L:4156
[code]....
View 1 Replies
View Related
Sep 1, 2009
I switched over to Fedora a couple of days ago. I'm using the built-in firewall shipped with it but I can't find out how to enable logging of dropped packets. Among others I'd like to use psad that needs firewall logging. Is there an easy way to do this? I'm not an iptables "expert".
View 6 Replies
View Related
Feb 20, 2010
For learning purposes i've set up a vpn between a laptop (running ubuntu) and a pc (running windows). The 2 computers are on the same lan. The VPN server is set on the laptop, and as a guide i used this tutorial:The problem is that the mtu on the ppp0 interface is 1396 and the mtu on the eth0 interface is 1492 so in order to pass packets from the et0 if to the ppp0 if, the laptop needs to fragment the packets, and here is where the problem appears: the packets come with the don't fragment bit set. I've tried lowering the mtu of the eth0 if but that didn't work. The only way i managed to make this work is setting the ppp0 mtu size to 1492. The thing is that setting the mtu and mru in the pptpd-options file to 1492 doesn't do anything (at least to solve this problem) and the only way to set the mtu of the ppp0 if is to manually set it using: Code:sudo ifconfig ppp0 mtu 1492 The issue with this is that every time the connection resets i have to enter the command.
View 2 Replies
View Related
Jul 6, 2011
my NIC drives me crazy and I need some help to gather all relevant informations to file a decent bug report. Maybe someone could guide me through this process.My mainboard is an AsRock Z68 Pro3
[URL]
I use a dual-boot setup with Windows7 installed in parallel to Fedora 15-x64. Whenever I had Windows in use and jjust reboot the system into Fedora, the NIC does not work as expected. Instead it goes in an endless "em1: link up" loop which results in very low bandwith or even complete network timeouts. This happens in Firefox as well as with yum or ping.
Quote:
Originally Posted by dmesg
[ 58.763294] r8169 0000:05:00.0: em1: link up
[ 59.686773] r8169 0000:05:00.0: em1: link up
[ 61.936454] r8169 0000:05:00.0: em1: link up
[code]....
If I directly cold boot into Fedora (after the power cord has been removed and the system got completely re-initialized) there are no problems at alll and I get a fast and stable network conection. This also happens with other linux distributions, for example SysRescCD.
View 1 Replies
View Related
Sep 27, 2010
I have a hardware device with two ethernet ports, eth0 and eth1 running Centos 5. Basically my goal is to forward packets from eth0->eth1 and eth1->eth0 as well as get a copy of these packets for analysis. If I set IP routing to do the forwarding then I won't get a copy of the packets for analysis.
View 3 Replies
View Related
May 18, 2010
I'm new to Debian and I have just installed it on three machines. To begin with they checked about 60 or so repos when doing an update. Then quite quickly this dropped to 48. I have removed the DVD media from the sources list after installation but that was before I saw this drop. It happened after an update as far as I can tell. I didn't think anything of it at the time. By the time all three were set up they were all only checking 48 repos. However I also have a VM, for trying out new stuff, and whilst that has been updated it still remains at about 60 (currently 59).
[Code]...
View 6 Replies
View Related
Jul 29, 2010
We have a high speed udp multicast connection. There are about 37 multicast groups and average incoming rate via the connection is about 20000 pkt/sec and peak 40000+ pkt/sec. Each packet is about 100-300 bytes. And there are 6 busiest multicast groups generating 80% of the traffic. No significant outgoing traffic via that interface. The problem is that, if our heavy-weight application create 37 sockets for all the groups, the packet loss become quite frequent. but if we create the 6 sockets for the busiest groups, the packet loss drops to 1/10 of the original level. We can confirm that the lost packets DO arrive in our box because a light-weight recorder on another box on the same ethernet segment can see the lost packets when listening to the same groups. If we start another heavy-weight application for the rest groups (31 groups ) on the same box, the packet loss just come back to the original level.
The packet loss happens not only to the heavy-weight application but also the light-weight recorder running on the same system. that is, the loss is system wide. The socket kernel buffer are all 4MB max and did not observe system buffer overflow. It seems the number of sockets listening to the same multicast group have the most negative impact on packet loss. And the higher traffic have a far less impact on packet loss than the number of sockets. It also seems that there is some limit in the kernel that when socket number are reduced under, the packet loss can significantly ease. How can I further diagnose the problem? Our system is RHEL 5.3 32bit i386, Xeon 2.9GHZ 16 Processors, 32GB memory. Two broadcom giga netowrk card and 6 Intel GIGA NIC, and only one interface card has so much traffic.
View 3 Replies
View Related
Jun 20, 2011
I'm trying to create and send my own ETH packets from inside the kernel.My objective to send the packages from layer 2 by building my own skbuffand sending itusingdev_queue_xmit().anyone did it or have examples of how to do it ?I tried to build my own skbuff without success.
View 1 Replies
View Related
Feb 8, 2010
i have a linux server runnig oracle applications. i need to access this server from putty using ssh through internet. i did by registering my static ip with the dnydns.org and i am able to connect to the server. but now there is no security to authenticate any user as any one knowing the password can login to it.
i thought of configuring the firewall of linux server but the client ip`s are not static and they change continiously. so thought of keeping one more pc between the server and the router which will do the work of authenticating. but i am confuse as how to configure it to allow the packets coming from the internet after authenticating and to by pass the packets generated from internal LAN?
View 8 Replies
View Related
Aug 30, 2010
i need to write a program in c that can sniff packets from Ethernet and distinguish RTP packets from Non-RTP packets, i have no idea what should i do
View 9 Replies
View Related
Jul 26, 2011
I'm trying to write a script that takes two arguments, the first argument is a number, and the second argument is a filename. The shell script should indicate if the file's size is BIGGER or SMALLER the number provided. this is what i have sofar, am i on the write track, i'm hoping its just a problem with my if command
if [ $1 -h $2 ]
then
echo "$1 is bigger than $2"
else
[code]....
View 2 Replies
View Related
Nov 3, 2010
is it possible to get the length or even the items of both queues, the run queue and the swap queue? I've googled a lot but had no luck. Maybe I havn't used the correct search words...
Is there any header and/or code example to use structures or any API to get these information from the kernel or the scheduler?
View 1 Replies
View Related
Oct 1, 2010
My wireless connection keeps getting dropped very frequently. I am on a Dell XPS m1530 and I will just be on the interent and it just disconnects from wireless and I have to connect back. It is super annoying. I am on the latest version of ubuntu.
View 4 Replies
View Related
Oct 11, 2010
my laptop running 10.10 and a dell. the college is witch i attend's unsecured wireless network keep disconnecting me from every on average 45 minutes to an hour ands will not re connect for about 10-15 minutes. it works fine anywhere else i go but here i get dropped.
View 1 Replies
View Related
Jul 11, 2010
I've been using my current laptop since Ubuntu Edgy Eft and, since then, I never had any problem with wireless ( Network controller: Intel Corporation PRO/Wireless 3945ABG [Golan] Network Connection (rev 02) ) Since I upgraded to Lucid, my connection is dropped approximately every 3-4 minutes for 10s. Network-manager doesn't show anything but it is well visible with the netspeed applet that shows a warning sign "No connection" instead of the speed.This is very annoying and frustrating. I recall having seen the same issue in an blog article where the author was talking about his upgrade to lucid. It was just one line and I didn't care a lot at the time and cannot find the article back.
Is there anyone having heard about a possible issue ? (I've upgraded from Karmic when Lucid was still in Beta, so it might be the cause).
View 1 Replies
View Related
Jul 4, 2011
I'm working right now with ubuntu 11.04 on my asus ul30vt-x1, my wireless n network is working on a linksys e3000 router, my issue is basically with long file transfers. When the issue started i was reaching speeds of 100 Mbps through my wireless network even when I'm connected at 150 Mbps. However when at this speed, I don't know why, the connection is dropped after some minutes or even seconds. I made some testing on windows, I'm reaching 70 Mbps there and no problem at all with dropping the connection.
So my conclusion is that for some reason the linux driver, in my case, is not able to handle such speed of 100 Mbps. I know that a wireless network will have a throughput of aprox 60% the wireless speed. Right now im trying to apply traffic shapping to my transfers so i can get 70 to 80 Mbps, its being working so far.
View 1 Replies
View Related
Mar 17, 2011
I've forwarded incoming connections on port 25 to my virtual machine with the following commands:
sudo iptables -t nat -A PREROUTING -p tcp -i eth0 -d 10.1.1.3 --dport 25 -j DNAT --to 192.168.56.101:25
sudo iptables -A FORWARD -p tcp -i eth0 -d 192.168.56.101 --dport 25 -j ACCEPT
The strange thing is the connections coming through in the virtual machine seem to be getting dropped. A port scan from the internet says the port is closed, but it is not the case as I can see the connection coming through. As you've probably worked out, I am running a mail server. When I send myself test mail, the connections from the senders mail server also gets dropped.
View 1 Replies
View Related
Jan 23, 2010
When I am running linux on my laptop, my ssh session to a particular server keeps getting randomly dropped. What should I do to troubleshoot the problem?
View 4 Replies
View Related
