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• How to extend a Linux PV partition online after virtual disk growth

  - by Yves Martin

  VMware allows to extend the size of a virtual disk online - when the VM is running. The next expected steps for Linux system are: extend the partition: delete and create a larger one with fdisk extend the PV size with pvresize use free extents for lvresize operations and then resize2fs for file system But I am stuck on the first step: fdisk and sfdisk still display the old size for the disk. My disk is a SCSI virtual disk connected thanks to the virtual LSI Logic controller. How to refresh the virtual disk size and partition table information available in Linux kernel without reboot ? As far as I know all that steps are possible for a running Windows, without reboot and even without any user actions thanks to VMWare tools. On Linux, I expects to do all steps online too and I already know steps 2, 3 and 4 work online. But the first one - change partition size declared in the partition table (still) seems to require a reboot. Update: My system is a Debian Lenny with kernel 2.6.26 and the disk I have extended is the main disk with a large PV containing the "root" LV for "/".

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• CentOS iscsi initiator has session but there is no block device

  - by jcalfee314

  I have installed the scsi-target-utils package on CentOS and I used it to perform a discovery. The discovery did give me an active session. I restarted the iscsi service but I do not see any new devices (fdisk -l). I see in /var/log/messages that my connection is operational now. I'm not sure how to debug this further. Can someone direct me into fixing this? discovery: iscsiadm -m discovery -t sendtargets -p 192.168.0.155 returns: 192.168.0.155:3260,-1 iqn.2009-02.com.twinstrata:cloudarray:sn-1d07c1b62d4ec8f3 Just to verify it actually worked: iscsiadm -m session returns tcp: [1] 192.168.0.155:3260,1 iqn.2009-02.com.twinstrata:cloudarray:sn-1d07c1b62d4ec8f3 restarting as the directions say to do: service iscsi restart output written to /var/log/message Stopping iscsi: Sep 20 12:14:22 localhost kernel: connection1:0: detected conn error (1020) [ OK ] Starting iscsi: Sep 20 12:14:22 localhost kernel: scsi1 : iSCSI Initiator over TCP/IP Sep 20 12:14:22 localhost iscsid: Connection1:0 to [target: iqn.2009-02.com.twinstrata:cloudarray:sn-1d07c1b62d4ec8f3, portal: 192.168.0.155,3260] through [iface: default] is shutdown. Sep 20 12:14:22 localhost iscsid: Could not set session2 priority. READ/WRITE throughout and latency could be affected. [ OK ] [root@db iscsi]# Sep 20 12:14:23 localhost iscsid: Connection2:0 to [target: iqn.2009-02.com.twinstrata:cloudarray:sn-1d07c1b62d4ec8f3, portal: 192.168.0.155,3260] through [iface: default] is operational now Ran a login command: iscsiadm -m node -T iqn.2009-02.com.twinstrata:cloudarray:sn-1d07c1b62d4ec8f3 -p 192.168.0.155 -l No errors, no logging occurred. Next I compared the output from "fdisk -l|egrep dev" both with the iscsi session and without. There is no difference. I suppose I could just look in /etc/mtab. Any ideas on how I can get an iscsi device?

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• Asus K50I sound issues

  - by MrStatic

  I have an Asus K50IJ (Bestbuy) laptop and have issues with my sound. Speakers themselves work fine but when I plug into the headphone jack it auto mutes the front channel and no sounds comes out of either the speakers or the headphones. If I then unmute the channel I get sound from both the speakers and the headphones. alsamixer shows the Headphone channel as all grayed out. /etc/modprobe.d/alsa-base.conf I have tried snd-hda-intel model="asus-laptop" and snd-hda-intel model="asus" In Sound Preferences I have gone to output and changed the Connector to 'Analog Headphones' that results in no sound from either speakers or headphones. As one forum suggested I tried to comment out blacklist snd_pcsp in the blacklist.conf which resulted in no change. lspci -v shows: 00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 03) Subsystem: Santa Cruz Operation Device 1043 Flags: bus master, fast devsel, latency 0, IRQ 45 Memory at fe9f4000 (64-bit, non-prefetchable) [size=16K] Capabilities: [50] Power Management version 2 Capabilities: [60] MSI: Enable+ Count=1/1 Maskable- 64bit+ Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00 Capabilities: [100] Virtual Channel Capabilities: [130] Root Complex Link Kernel driver in use: HDA Intel Kernel modules: snd-hda-intel

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• Routing table on Linux not respected

  - by MRHaarmann

  I have a very specific problem, building a Linux VPN endpoint (with external VPN Gateway), which should route certain networks over the tunnel, others via default gateway. The Linux VPN should do a NAT on the outgoing connections for the VPN peers. Setup is as following: Internet gateway LAN 192.168.25.1/24 VPN Gateway LAN 10.45.99.2/24 (VPN tunnel 10.45.99.1 to net 87.115.17.40/29, separate connection to Internet) Linux VPN Router eth0 192.168.25.71/24 eth0:503 10.45.99.1/24 Default 192.168.25.1 route to 87.115.17.40/29 via 10.45.99.2 (send_redirects disabled, ip_forward enabled) Linux clients (multiple): eth0 192.168.25.x/24 Default 192.168.25.1 route to 87.115.17.40/29 via 192.168.25.71 Ping to the machines via tunnel from the VPN Router is working. Now I want to establish a routing from my clients over the VPN gateway and the client packet gets routed to 192.168.25.1 ! traceroute output shows the packets get routed to 192.168.25.71, but then to 192.168.25.1. So the route is not respected in forward ! IPTables and Routing: ip route show 87.115.17.40/29 via 10.45.99.2 dev eth0 10.45.99.0/24 dev eth0 proto kernel scope link src 10.45.99.1 192.168.25.0/24 dev eth0 proto kernel scope link src 192.168.25.71 default via 192.168.25.1 dev eth0 iptables -A INPUT -i eth0:503 -j REJECT iptables -t nat -A POSTROUTING -o eth0:503 -j MASQUERADE iptables -A FORWARD -i eth0:503 -m state --state RELATED,ESTABLISHED -j ACCEPT iptables -A FORWARD -s 192.168.25.0/24 -o eth0:503 -j ACCEPT So what is wrong with my setup ? The route is chosen correctly from localhost, but all the clients get forwarded to the Internet GW. thanks for helping, Marcus

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• How can I switch from a custom linux network namespace back to the default one?

  - by Martin

  With ip netns exec you can execute a command in a custom network namespace - but is there also a way to execute a command in the default namespace? For example, after executing these two commands: sudo ip netns add test_ns sudo ip netns exec test_ns bash How can the newly created bash execute programs in the default network namespace? There is no ip netns exec default or anything similar as far as I've found. My scenario is: I want to run a SSH server in a separate network namespace (to keep the rest of the system unaware of the network connection, as the system is used for network testing), but want to be able to execute programs in the default network namespace via the SSH connection. What I've found out so far: Created network namespaces are listed as files under /var/run/netns (but there is no file for the default namespace) The ip netns exec code can be found here: http://git.kernel.org/cgit/linux/kernel/git/shemminger/iproute2.git/tree/ip/ipnetns.c#n132 - I haven't grasped everything that it is doing yet, but it doesn't look very promising. ip netns identify $$ as suggested by Howto query and change network namespace on linux? returns nothing when in the default network namespace

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• Sudden problems with iptables not running

  - by Fourjays

  I've got a sudden issue with iptables not running on my CentOS 5.8/DirectAdmin XenVPS. All I have done today is install PHP APC and run an update (although I admittedly didn't pay much attention today - I usually do). Iptables has been running fairly smoothly since I installed it over 6 months ago. Basically when I try to run iptables -L it tells me: iptables v1.3.5: can't initialize iptables table `filter': iptables who? (do you need to insmod?) Perhaps iptables or your kernel needs to be upgraded. I've looked around and tried a few things and it appears that maybe my kernel doesn't have the modules loaded? I've been reading this and tried the two commands they suggest to no avail. Except there does appear to be a mismatch on one bit of output: -bash-3.2# cd /lib/modules -bash-3.2# ls 2.6.18-194.32.1.el5xen 2.6.18-238.5.1.el5xen 2.6.18-274.7.1.el5xen 2.6.39.1-cs-domU 2.6.18-238.12.1.el5xen 2.6.18-238.9.1.el5xen 2.6.37.2-cs-domU 3.0.1-cs-domU -bash-3.2# depmod -a WARNING: Couldn't open directory /lib/modules/2.6.18-274.18.1.el5xen: No such file or directory FATAL: Could not open /lib/modules/2.6.18-274.18.1.el5xen/modules.dep.temp for writing: No such file or directory Does this mean the versions are out of sync? If so, what are my next steps to getting this fixed? As you can probably tell I am still learning how to manage my server so please be very clear in all advice. Many thanks :)

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• Multiple logins with pam_mount means multiple (redundant) mounts ...

  - by Jamie

  I've configured pam_mount.so to automagically mount a cifs share when users login; the problem is if a user logs into multiple times simultaneously, the mount command is repeated multiple times. This so far isn't a problem but it's messy when you look at the output of a mount command. # mount /dev/sda1 on / type ext4 (rw,errors=remount-ro) proc on /proc type proc (rw,noexec,nosuid,nodev) none on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) none on /dev type devtmpfs (rw,mode=0755) none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) none on /dev/shm type tmpfs (rw,nosuid,nodev) none on /var/run type tmpfs (rw,nosuid,mode=0755) none on /var/lock type tmpfs (rw,noexec,nosuid,nodev) none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755) //srv1/UserShares/jrisk on /home/jrisk type cifs (rw,mand) //srv1/UserShares/jrisk on /home/jrisk type cifs (rw,mand) //srv1/UserShares/jrisk on /home/jrisk type cifs (rw,mand) I'm assuming I need to fiddle with either the pam.d/common-auth file or pam_mount.conf.xml to accomplish this. How can I instruct pam_mount.so to avoid duplicate mountings?

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• Where is '/host' declared for mount in Wubi (Ubuntu 9.10)?

  - by Pedro

  I'm using Wubi (ubuntu 9.10), and I couldn't find where '/host' mountpoint is declared for mounting. There's no entry in fstab, but it's listed in /proc/mount and mounted at boot time. Any ideas? pedroel@ubuntu:~$ cat /proc/mounts rootfs / rootfs rw 0 0 none /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0 none /proc proc rw,nosuid,nodev,noexec,relatime 0 0 udev /dev tmpfs rw,relatime,mode=755 0 0 /dev/sda1 /host fuseblk rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,blksize=4096 0 0 /dev/loop0 / ext4 rw,relatime,errors=remount-ro,barrier=1,data=ordered 0 0 none /sys/kernel/security securityfs rw,relatime 0 0 none /sys/fs/fuse/connections fusectl rw,relatime 0 0 none /sys/kernel/debug debugfs rw,relatime 0 0 none /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0 none /dev/shm tmpfs rw,nosuid,nodev,relatime 0 0 none /var/run tmpfs rw,nosuid,relatime,mode=755 0 0 none /var/lock tmpfs rw,nosuid,nodev,noexec,relatime 0 0 none /lib/init/rw tmpfs rw,nosuid,relatime,mode=755 0 0 /dev/loop1 /home/pedroel/Downloads ext4 rw,relatime,errors=remount-ro,barrier=1,data=ordered 0 0 binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0 0 gvfs-fuse-daemon /home/pedroel/.gvfs fuse.gvfs-fuse-daemon rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0 /dev/mapper/isw_efhafcifi_RAID_Volume01 /media/RAID_D fuseblk rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096 0 0 pedroel@ubuntu:~$ cat /etc/fstab # /etc/fstab: static file system information. # # Use 'blkid -o value -s UUID' to print the universally unique identifier # for a device; this may be used with UUID= as a more robust way to name # devices that works even if disks are added and removed. See fstab(5). # # proc /proc proc defaults 0 0 /host/ubuntu/disks/root.disk / ext4 loop,errors=remount-ro 0 1 /host/ubuntu/disks/pedro.disk /home/pedroel/Downloads ext4 loop,errors=remount-ro 0 1 /host/ubuntu/disks/swap.disk none swap loop,sw 0 0 /dev/fd0 /media/floppy0 auto rw,user,noauto,exec,utf8 0 0 Thanks in advance, Pedro

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• Poor write performance on Debian server running NFS with 22TB exported JFS filesystem

  - by user143546

  I am currently running a debian server that is exporting a large JFS filesystem (22TB) over NFS (nfs-kernel-server.) When attempting to write to the NFS share, the performance is very poor. The 22TB disk is sitting on a NAS mounted using iSCSI. It will bust for a moment near expected line speed, and then sit idle for several seconds. Very little traffic measured in the low kb/sec. The wait peeks on write. When reading from the NFS mount, the system operates at expected speeds (11MB/sec). The issue does not occur when using SFTP, rsync, or local coping (non-nfs). The issue persists between stable and testing releases. On the same machine I have a 14TB ext4 filesystem using the exact same export configuration that does not share the issue. This share is not in regular use and thus not consuming resources. NFS Server: cat /etc/exports /data2 10.1.20.86(rw,no_subtree_check,async,all_squash) cat /sys/block/sdb/queue/scheduler noop [deadline] cfq cat /etc/default/nfs-kernel-server RPCNFSDCOUNT=8 RPCNFSDPRIORITY=0 RPCMOUNTDOPTS=--manage-gids NEED_SVCGSSD= RPCSVCGSSDOPTS= NFS Client: cat /etc/fstab 10.1.20.100:/data2 /root/incoming nfs rw,noatime,soft,intr,noacl 0 2 cat /sys/block/sdb/queue/scheduler noop [deadline] cfq cat /proc/mounts 10.1.20.100:/data2/ /root/incoming nfs4 rw,noatime,vers=4,rsize=262144,wsize=262144,namlen=255,soft,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=10.1.20.86,minorversion=0,addr=10.1.20.100 0 0 This problem has me pretty stumped. Any help would be greatly welcomed. Thanks.

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• OpenVPN + iptables / NAT routing

  - by Mikeage

  Hi, I'm trying to set up an OpenVPN VPN, which will carry some (but not all) traffic from the clients to the internet via the OpenVPN server. My OpenVPN server has a public IP on eth0, and is using tap0 to create a local network, 192.168.2.x. I have a client which connects from local IP 192.168.1.101 and gets VPN IP 192.168.2.3. On the server, I ran: iptables -A INPUT -i tap+ -j ACCEPT iptables -A FORWARD -i tap+ -j ACCEPT iptables -t nat -A POSTROUTING -s 192.168.2.0/24 -o eth0 -j MASQUERADE On the client, the default remains to route via 192.168.1.1. In order to point it to 192.168.2.1 for HTTP, I ran ip rule add fwmark 0x50 table 200 ip route add table 200 default via 192.168.2.1 iptables -t mangle -A OUTPUT -j MARK -p tcp --dport 80 --set-mark 80 Now, if I try accessing a website on the client (say, wget google.com), it just hangs there. On the server, I can see $ sudo tcpdump -n -i tap0 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on tap0, link-type EN10MB (Ethernet), capture size 96 bytes 05:39:07.928358 IP 192.168.1.101.34941 > 74.125.67.100.80: S 4254520618:4254520618(0) win 5840 <mss 1334,sackOK,timestamp 558838 0,nop,wscale 5> 05:39:10.751921 IP 192.168.1.101.34941 > 74.125.67.100.80: S 4254520618:4254520618(0) win 5840 <mss 1334,sackOK,timestamp 559588 0,nop,wscale 5> Where 74.125.67.100 is the IP it gets for google.com . Why isn't the MASQUERADE working? More precisely, I see that the source showing up as 192.168.1.101 -- shouldn't there be something to indicate that it came from the VPN? Edit: Some routes [from the client] $ ip route show table main 192.168.2.0/24 dev tap0 proto kernel scope link src 192.168.2.4 192.168.1.0/24 dev wlan0 proto kernel scope link src 192.168.1.101 metric 2 169.254.0.0/16 dev wlan0 scope link metric 1000 default via 192.168.1.1 dev wlan0 proto static $ ip route show table 200 default via 192.168.2.1 dev tap0

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• Problem with ubuntu 10.10 running from USB drive

  - by Surjya Narayana Padhi

  Hi Geeks, I recently downloaded Ubuntu 10.10 and created an USB drive with that. I started to run the Ubuntu from that USB drive. But I am facing so much problem. I am thinking why its not so much easy like Windows to do all my job in ubuntu. Always I get some error message or to install something. This time I am getting the following errors. I am trying to download and install Aircrack-ng. So used the command sudo apt-get install aircrack-ng. But the installation stops with the following error : update-initramfs: deferring update (trigger activated) cp: cannot stat `/vmlinuz': No such file or directory dpkg: error processing bcmwl-kernel-source (--configure): subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing: initramfs-tools bcmwl-kernel-source E: Sub-process /usr/bin/dpkg returned an error code (1) I don't even have the aptitude command installed till now. Are all these errors because of I am running the ubuntu from USB drive? Is there any simple and easy way to go to Ubuntu Software Center and download all the required essentials at one shot and then Aircrack-ng? I could not find the Aircrack-ng in Ubuntu Software Center Can anybody give me detail steps to solve all my problems above. I am frustrated searching for updates and installations. When something works and something does not work. Can anybody suggest me how I should proceed after installing ubuntu to run on a USB drive. So that I can use the OS like Windows. Like software download,wireless driver, sound, video, documents, C:, D: all things should be there. Please somebody help.

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• Xen domU mem-set issue

  - by Casper Langemeijer

  I'm running into a problem on my xen 4.0.1 server (debian squeeze) My host has 32G of memory, Domain-0 has 2048 M assigned to it. (scaled down with xm mem-set Domain-0 2048) top in Domain-0 confirms this. I created a virtual machine config file (using xen-tools) with the following options: memory = '512' maxmem = '2048' Both host and guest machines are running the standard 2.6.32-5-xen-amd64 debian kernel. 'xm create' creates a virtual machine with 512MB of memory as expected. Then 'xm mem-set domU 1024' will not expand the memory to 1024MB running 'xm mem-set domU 400' does set the memory to about 400MB Then 'xm mem-set domU 1024' will expands the memory back to 512MB Based on this, you would say that xm ignores the maxmem and silently sets maxmem to 512, but in the output of xm top the MAXMEM column reads 2G. the MEM column will not go over 512M. The output of xm list tells another story, it shows 1024 when I 'xm mem-set domU 1024'. I've googled myself all away around the internet for this issue and found that most people don't scale back Domain-0. I know I've seen a bugreport about the issue I'm experiencing, but can't find it anymore. Does anyone see what I'm doing wrong here? Hmm.. I just upgraded my kernel to the one provided by debian backports. The issue has gone.

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• Problem with ubuntu 10.10 running from USB drive

  - by Surjya Narayana Padhi

  I recently downloaded Ubuntu 10.10 and created an USB drive with that. I started to run the Ubuntu from that USB drive. But I am facing so much problem. I am thinking why its not so much easy like Windows to do all my job in ubuntu. Always I get some error message or to install something. This time I am getting the following errors. I am trying to download and install Aircrack-ng. So used the command sudo apt-get install aircrack-ng. But the installation stops with the following error : update-initramfs: deferring update (trigger activated) cp: cannot stat `/vmlinuz': No such file or directory dpkg: error processing bcmwl-kernel-source (--configure): subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing: initramfs-tools bcmwl-kernel-source E: Sub-process /usr/bin/dpkg returned an error code (1) I don't even have the aptitude command installed till now. Are all these errors because of I am running the ubuntu from USB drive? Is there any simple and easy way to go to Ubuntu Software Center and download all the required essentials at one shot and then Aircrack-ng? I could not find the Aircrack-ng in Ubuntu Software Center Can anybody give me detail steps to solve all my problems above. I am frustrated searching for updates and installations. When something works and something does not work. Can anybody suggest me how I should proceed after installing ubuntu to run on a USB drive. So that I can use the OS like Windows. Like software download,wireless driver, sound, video, documents, C:, D: all things should be there. Please somebody help.

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• GRUB having problems with my sda1 UUID

  - by Igoru

  I was having trouble trying to setup triple boot on my computer... (Take a look at this thread if you think it would help). I ended up by having a GRUB menu that has Ubuntu entries and "Windows" entry, that calls an EasyBCD menu to choose between Windows 7 and XP. Everything would be fine if, only if, GRUB was set up correctly. I can't find why, but it throws me this when I try to open Ubuntu: I've already tried to remove the menu.lst and do a grub-update, and a grub-install too. I tried to create a symlink to /dev/sda1 at /dev/disk/by-uuid/<<uuid that is there>>, just like the other UUIDs that were there... But I couldn't find that symlink at that busybox that opened when it thrown me the error. Any ideas? [UPDATE] This is the GRUB entry with problems: title Ubuntu 9.04, kernel 2.6.28-15-generic uuid b1ed36e5-4d84-4eb8-86ef-6f1135ffc238 kernel /boot/vmlinuz-2.6.28-15-generic root=UUID=b1ed36e5-4d84-4eb8-86ef-6f1135ffc238 ro quiet splash initrd /boot/initrd.img-2.6.28-15-generic quiet And this my /dev/disk/by-uuid folder: 04DCBCFBDCBCE856 - ../../sdb1 (NTFS backup disk) 4434E77734E769FE - ../../sda4 (NTFS WinXP) ACB09F0DB09EDCE0 - ../../sda2 (NTFS Win7) b5311be8-a853-4fdd-aed5-d65974b3c0c4 - ../../sda5 (EXT4 home) C04B-4D97 - ../../sdc (FAT32 live-pendrive from which i'm running) D28447F68447DB9B - ../../sda6 (NTFS files partition) e0e88f38-d815-423a-9d5e-64b9c74a8b92 - ../../sda7 (swap)

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• iptables drops some packets on port 80 and i don't know the cause.

  - by Janning

  Hi, We are running a firewall with iptables on our Debian Lenny system. I show you only the relevant entries of our firewall. Chain INPUT (policy DROP 0 packets, 0 bytes) target prot opt in out source destination ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 state NEW Chain OUTPUT (policy DROP 0 packets, 0 bytes) target prot opt in out source destination ACCEPT all -- * lo 0.0.0.0/0 0.0.0.0/0 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED LOGDROP all -- * * 0.0.0.0/0 0.0.0.0/0 Some packets get dropped each day with log messages like this: Feb 5 15:11:02 host1 kernel: [104332.409003] dropped IN= OUT=eth0 SRC= DST= LEN=1420 TOS=0x00 PREC=0x00 TTL=64 ID=18576 DF PROTO=TCP SPT=80 DPT=59327 WINDOW=54 RES=0x00 ACK URGP=0 for privacy reasons I replaced IP Addresses with and This is no reason for any concern, but I just want to understand what's happening. The web server tries to send a packet to the client, but the firewall somehow came to the conclusion that this packet is "UNRELATED" to any prior traffic. I have set a kernel parameter ip_conntrack_ma to a high enough value to be sure to get all connections tracked by iptables state module: sysctl -w net.ipv4.netfilter.ip_conntrack_max=524288 What's funny about that is I get one connection drop every 20 minutes: 06:34:54 droppedIN= 06:52:10 droppedIN= 07:10:48 droppedIN= 07:30:55 droppedIN= 07:51:29 droppedIN= 08:10:47 droppedIN= 08:31:00 droppedIN= 08:50:52 droppedIN= 09:10:50 droppedIN= 09:30:52 droppedIN= 09:50:49 droppedIN= 10:11:00 droppedIN= 10:30:50 droppedIN= 10:50:56 droppedIN= 11:10:53 droppedIN= 11:31:00 droppedIN= 11:50:49 droppedIN= 12:10:49 droppedIN= 12:30:50 droppedIN= 12:50:51 droppedIN= 13:10:49 droppedIN= 13:30:57 droppedIN= 13:51:01 droppedIN= 14:11:12 droppedIN= 14:31:32 droppedIN= 14:50:59 droppedIN= 15:11:02 droppedIN= That's from today, but on other days it looks like this, too (sometimes the rate varies). What might be the reason? Any help is greatly appreciated. kind regards Janning

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• Kickstarting an Ubuntu Server 10.04 installation (DHCP fails)

  - by William

  I'm trying to automate the network installation of Ubuntu 10.04 LTS with an anaconda kickstart and everything seems to running except for the initial DHCP autoconfiguration. The installer attempts to configure the install via DHCP but fails on its first attempt. This brings me to a prompt where I can retry DHCP and it seems to always work on the second attempt. My issue is that this is not really automated if I have to hit retry for DHCP. Is there something I can add to the kickstart file so that it will automatically retry or better yet not fail the first time? Thanks. Kickstart: # System language lang en_US # Language modules to install langsupport en_US # System keyboard keyboard us # System mouse mouse # System timezone timezone America/New_York # Root password rootpw --iscrypted $1$unrsWyF2$B0W.k2h1roBSSFmUDsW0r/ # Initial user user --disabled # Reboot after installation reboot # Use text mode install text # Install OS instead of upgrade install # Use Web installation url --url=http://10.16.0.1/cobbler/ks_mirror/ubuntu-10.04-x86_64/ # System bootloader configuration bootloader --location=mbr # Clear the Master Boot Record zerombr yes # Partition clearing information clearpart --all --initlabel # Disk partitioning information part swap --size 512 part / --fstype ext3 --size 1 --grow # System authorization infomation auth --useshadow --enablemd5 %include /tmp/pre_install_ubuntu_network_config # Always install the server kernel. preseed --owner d-i base-installer/kernel/override-image string linux-server # Install the Ubuntu Server seed. preseed --owner tasksel tasksel/force-tasks string server # Firewall configuration firewall --disabled # Do not configure the X Window System skipx %pre wget "http://10.16.0.1/cblr/svc/op/trig/mode/pre/system/Test-D" -O /dev/null # Network information # Start pre_install_network_config generated code # Start of code to match cobbler system interfaces to physical interfaces by their mac addresses # Start eth0 # Configuring eth0 (00:1A:64:36:B1:C8) if ip -o link show | grep -i 00:1A:64:36:B1:C8 then IFNAME=$(ip -o link show | grep -i 00:1A:64:36:B1:C8 | cut -d" " -f2 | tr -d :) echo "network --device=$IFNAME --bootproto=dhcp" >> /tmp/pre_install_ubuntu_network_config fi # End pre_install_network_config generated code %packages openssh-server

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• SSH not working through Double NAT

  - by d_inevitable

  I am trying to setup port forwarding for ssh through 2 NATs The first Router translates my internet IP to my outer network (10.1.7.0). In the outer network there's a second Router that does NAT to my inner network (192.168.1.0). The target server is connected to both, the outer network and the inner network. I cannot change the port forwarding options for outer router. It is currently configured to forward the SSH and HTTP port to the router for the inner network. Internet + | v +-----------------+ +------------------+ | Outer Router | | Inner Router | |-----------------| |------------------| | | SSH HTTP | | +----+ +--------------------->| | | | | | | | | | | | | +-------+---------+ +------+---------+-+ | | | | | | | | | | | | | | +------------------+ | SSH | | | | Server | | | | | |------------------| | | | +-----------> |<-------+ | | | | |HTTP (testing) | +------------------+ | | | +------v------------------+ | | Outer Workstation | +-------------------+ | |-------------------------| | Inner Workstation| | | | |-------------------| | | | | |<----------------+ +-------------------------+ | | +-------------------+ When connecting from a outer workstation to the address of the inner router, then both SSH and HTTP work fine. When connecting from the internet to my public ip with HTTP, the connection works fine as well. However SSH just times out. Most likely because the reply is not routed back properly. I suspect its either because of the SSH itself, or because the server is connected to both, the inner and outer network. Any ideas how I could resolve this issue? The routes on the server are currently: ip route show default via 10.1.7.254 dev eth0 metric 100 10.1.7.0/24 dev eth0 proto kernel scope link src 10.1.7.1 192.168.1.0/24 dev eth1 proto kernel scope link src 192.168.1.2 Do I have to change this? If so how?

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• Limited connections to Ubuntu 12.04 server

  - by Luis M. Valenzuela

  I'm having a weird problem with my server. The server is inside my network, connected to a 3com switch which is connected to the router that handles the internet connection. The main purpose of the server is to host a php application. What's happening is that user 1 to 15 in the private network have no problems connecting to the server, when user 16 tries to connect a time out comes out and is unable to connect to the server. It's not just to the php application, but to any service from the server. When the 15 users are using the application, the server doesn't even answer to ping. I haven't set any special limit in Apache's ini file or MySql and the firewall is being turned off because the server is only to give service to the internal network. Is there a parameter in any of the network's card conf. files that might me causing this ? Or should I suspect from the router's or switches configuration ? UPDATE. Tomorrow, I'm gonna do some test on the server modifying two kernel params in : /etc/sysctl.conf The settings are: net.core.somaxconn which has the limit on simultaneous network connections to the server and kernel.shmmax which controls the amount of memory the system can use for managing connections.

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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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• Small maximum number of connections on a Linux router

  - by Eugene

  I have a Linux box acting as a router with no iptables or other firewall and no networking applications running on it, just pure router. I've put it in a test environment that generates many TCP connections, each having unique source and destination IP, and those connections go through this router. I'm observing that number of connections successfully created rise to approximately 500 and then no more connections can be created for several minutes, then another 100 connections can be created and there is another pause, and so on. If 10 connections for each source-destination pair are created, then maximum numbers go about 10 times up, so the problem is probably with many connections from different IPs. As traffic is simply routed, it doesn't have to do with number of file descriptors, iptables connection tracking and other things often proposed to check in similar cases. The box has plenty of free RAM and CPU, both NICs are gigabit. The kernel is 2.6.32. I've already tried increasing net.core.*mem_max, net.core.netdev_max_backlog and txqueuelen on both NICs, with completely no effect. What else should I check ? Is there some rate-limit in the kernel itself ?

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• Separated virtual networks with same subnet range with 2 interface

  - by Coolpet

  I'm having some problems with routing with the following: I have a server with 2 interfaces. It has 1-1 alias contains the same subnet. the 2 interface is connected to 2 switch, which are separated from each other. Infrastructure: Eth0 192.168.16.2/20 Eth0:eth0 192.168.1.222/20 Eth1 192.168.32.3/20 Eth1:eth1 192.168.1.223/20 I have a PC which has the IP address: 192.168.1.3/24 The problem is the next: If PC is on subnet 1, I can ping it. If PC is on subnet 2, I can't ping it. traceroute shows the route is across 192.168.1.222 ping -I 192.168.1.223 192.168.1.3 is not working on subnet 2. arp entries show the MAC address belonging to the correct interface (eth1 on subnet 2) How can I force the server to look on both interface same ranged subnet for specific IP? It searches only in the first subnet. The routing table has these 2 entries: 192.168.0.0/20 dev eth0 proto kernel scope link src 192.168.1.222 192.168.0.0/20 dev eth1 proto kernel scope link src 192.168.1.223

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• Sound doesn't work anymore after replacing RAM

  - by thejh

  Hello, today, I replaced one old RAM module with two newer, bigger ones, but now, the sound doesn't seem to work anymore. Already ran alsaconf and it didn't help. Output of lspci for the audio device: 00:07.0 Audio device: nVidia Corporation MCP67 High Definition Audio (rev a1) Subsystem: Giga-byte Technology Device a002 Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 0 (500ns min, 1250ns max) Interrupt: pin A routed to IRQ 21 Region 0: Memory at f5100000 (32-bit, non-prefetchable) [size=16K] Capabilities: [44] Power Management version 2 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot+,D3cold+) Status: D0 PME-Enable- DSel=0 DScale=0 PME- Capabilities: [50] Message Signalled Interrupts: Mask+ 64bit+ Queue=0/0 Enable- Address: 0000000000000000 Data: 0000 Masking: 00000000 Pending: 00000000 Capabilities: [6c] HyperTransport: MSI Mapping Enable+ Fixed+ Kernel driver in use: HDA Intel Kernel modules: snd-hda-intel The audio device is onboard and has six configurable outputs, two or so are also capable of being an input (if I remember it correctly), but I don't know how to control it under linux. Does somebody know how/whether replacing the RAM could be related to my problem and/or how to fix it?

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• Linux Centos 6 becomes unavailable from time to time - OS&network issue

  - by adoado0

  I am encountering following problem. There is one server (DL160 G5) running Centos 6.3 with default kernel 2.6.32-220.2.1.el6.x86_64 - at this point I'd like to add that issue appeared also at older version - 6.1 and older kernel (do not remember exactly which version). There is cPanel installed and from time to time it becomes unavailable (network connection). What I've checked is (via KVMoIP): load average is completely normal it does not lack memory or disk space when problem occurs no console notifications checked all access logs and there is no sign that it can be caused by a client script cannot even access local interface (127.0.0.1) or main IP address running tcpdump I can only see packets arriving to server - no responses all services seem to be running properly (mail,sql,http,ssh) checked crontab and all clients' crontabs too network port utilisation is low ( up to several Mbits) arriving packet rate is low - hundreds per second (according to tcpdump) console (via kvmoip) works fine, no lags there is no conntrack at this server there is no ipv6 at this server flushing iptables, unloading modules does not resolve problem restarting network does not resolve problem, no errors appear it also occurs when two sepearate networks are configured (and multiple gateways) as well as one IP, one default gw and one network is configured - so it seems network configuration independent it seems to repeat randomly (load,packet rate,bandwith usage,load independent) checked server with different rootkit detection tools - it seems to be clean server has been rebooted, it did not change anything there are no interface errors it apperas randomly can be once a week or several times per day It usually works fine after 1-15 minutes. What I can also check? It is definitely OS issue - there is traffic at interface only in one direction when problem occurs, can not even ping loopback. Any ideas? Recommended checks? Anything I did not checked above.

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• OpenVPN + iptables / NAT routing

  - by Mikeage

  I'm trying to set up an OpenVPN VPN, which will carry some (but not all) traffic from the clients to the internet via the OpenVPN server. My OpenVPN server has a public IP on eth0, and is using tap0 to create a local network, 192.168.2.x. I have a client which connects from local IP 192.168.1.101 and gets VPN IP 192.168.2.3. On the server, I ran: iptables -A INPUT -i tap+ -j ACCEPT iptables -A FORWARD -i tap+ -j ACCEPT iptables -t nat -A POSTROUTING -s 192.168.2.0/24 -o eth0 -j MASQUERADE On the client, the default remains to route via 192.168.1.1. In order to point it to 192.168.2.1 for HTTP, I ran ip rule add fwmark 0x50 table 200 ip route add table 200 default via 192.168.2.1 iptables -t mangle -A OUTPUT -j MARK -p tcp --dport 80 --set-mark 80 Now, if I try accessing a website on the client (say, wget google.com), it just hangs there. On the server, I can see $ sudo tcpdump -n -i tap0 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on tap0, link-type EN10MB (Ethernet), capture size 96 bytes 05:39:07.928358 IP 192.168.1.101.34941 > 74.125.67.100.80: S 4254520618:4254520618(0) win 5840 <mss 1334,sackOK,timestamp 558838 0,nop,wscale 5> 05:39:10.751921 IP 192.168.1.101.34941 > 74.125.67.100.80: S 4254520618:4254520618(0) win 5840 <mss 1334,sackOK,timestamp 559588 0,nop,wscale 5> Where 74.125.67.100 is the IP it gets for google.com . Why isn't the MASQUERADE working? More precisely, I see that the source showing up as 192.168.1.101 -- shouldn't there be something to indicate that it came from the VPN? Edit: Some routes [from the client] $ ip route show table main 192.168.2.0/24 dev tap0 proto kernel scope link src 192.168.2.4 192.168.1.0/24 dev wlan0 proto kernel scope link src 192.168.1.101 metric 2 169.254.0.0/16 dev wlan0 scope link metric 1000 default via 192.168.1.1 dev wlan0 proto static $ ip route show table 200 default via 192.168.2.1 dev tap0

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• Mysterious swap usage on EC2

  - by rusty

  We're in the middle of a project to move our infrastructure from a co-lo situation into Amazon EC2 and we've noticed some weird memory characteristics of the processes in our setup. Without going into too much detail about the specifics of our processes, we've noticed that on our EC2 instances "top" will show processes using a lot of swap space -- in fact, much greater than the amount of available swap or (if you add it all up) more than the available disk. Here's a sample top output: Mem: 7136868k total, 5272300k used, 1864568k free, 256876k buffers Swap: 1048572k total, 0k used, 1048572k free, 2526504k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ SWAP COMMAND 4121 jboss 20 0 5913m 603m 14m S 0.7 8.7 3:59.90 5.2g java 22730 root 20 0 2394m 4012 1976 S 2.0 0.1 4:20.57 2.3g PassengerHelper 20564 rails 20 0 2539m 220m 9828 S 0.3 3.2 0:23.58 2.3g java 1423 nscd 20 0 877m 1464 972 S 0.0 0.0 0:03.89 876m nscd You can see, for instance, that jboss is reportedly using 5.2 gigs of swap space which is definitely impossible since there's only 1G allocated and none is being used (probably because there's still 1.8G of RAM free). And here's the results of uname -a: Linux xxx.yyy.zzz 2.6.35.14-106.53.amzn1.x86_64 #1 SMP Fri Jan 6 16:20:10 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux We're running an AMI based off of the default Amazon Linux AMI (Amazon Linux AMI release 2011.09, so some RHEL5 and RHEL 6) with not too many customizations and definitely no kernel-level customizations. Something here tells me that on this particular kernel/distribution, the reporting of swap or maybe even total memory usage isn't what it appears to be... Any help would be appreciated!

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