Linux is the generic term for a UNIX-like open source operating system based on the Linux kernel.

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35 views

SynProxy can not return syn ack packets with asymmetric dual bridge topology

I have a asymmetric dual bridge topology as shown below when i connect from 172.16.11.5 and 172.16.10.6 with ssh but i can not connect because of SynProxy. ------- ...
4
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560 views

Docker: Permission denied on folders added with ADD

I'm trying to configure a postgresql installation using docker. FROM ubuntu:13.10 ADD . /db # install postgres # ... RUN chown postgres:postgres /db -R && \ chmod 700 /db -R USER ...
4
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144 views

CPU load inhibits interrupts on Linux

I have an Ubuntu box with 3.2 kernel, CPU with 2 cores and CAN (Controller Area Network) card based on SJA1000 controller attached via PCI bus. I'm testing receive capabilities of the card. It can ...
3
votes
0answers
97 views

SSSD process won't die

Thanks for taking the time to check out my problem. I'm currently working on an issue that has only appeared once before. Back on Jan 3rd when this first appeared we were able to reboot the server ...
3
votes
0answers
144 views

Not Able to Mount USB HDD in Linux

I'm having a problem with a server that I just installed kernel 2.6.18-371.el5 on. It's an old kernel for Red Hat 5, I know, but due to certain "restrictions" I am forced into using that for the time ...
3
votes
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36 views

How can I introspect the “shared subtree” mount flags for a particular mount?

Under Linux, the shared subtree flags control how a mountpoint is shared with parent and child mount namespaces. These flags include MS_SHARED, MS_PRIVATE, and MS_SLAVE. How can one see which of ...
3
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0answers
725 views

kworker consuming +90% IO and zero disk write

this is a standard apache web server on AWS Linux AMI + EBS. We are noticing high load average (+8) and iotop -a shows: Total DISK READ: 0.00 B/s | Total DISK WRITE: 2.37 M/s TID PRIO USER ...
3
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0answers
177 views

TCP Window Scaling Problem over MPLS

After extensive troubleshooting why the TCP speed over an MPLS circuit is slow in one direction, I figured out that by adjusting the TCP window size the situation improved a lot. Maybe you can tell me ...
3
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182 views

TCP congestion collapse

I am experiencing suboptimal performance on an EC2 instance connecting to an RDS instance. This particular instance was built before VPC's existed, so all the traffic is flowing through a single ...
3
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0answers
298 views

TCP connection stuck in SYN_RECV state despite ACK received

My client and server are both internal machines. tcpdump on both client and server show all three parts of handshake are communicated, however netstat on server shows SYN_RECV, and on client shows ...
3
votes
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481 views

Adaptec pm80xx Driver Drops Drives Randomly

I'm building a ZFS NAS using an Adaptec ASA-71605H HBA on Ubuntu 12.04.4. Modern Linux kernels ship with the open-source version of the required pm80xx kernel module. Adaptec provides a driver for ...
3
votes
0answers
143 views

timing issue after route add/delete (route not used)

I have an application that is running a raw IP socket, destination of this socket is governed by routes installed via the 'ip route add' command. These routes can change during the lifetime of a ...
3
votes
0answers
161 views

nginx and cloudlfare ip confusion?

I am using the below config in http block of my nginx.conf to get real ip while using Cloudflare acceleration service: ## Cloudflare settings to get Real IP's set_real_ip_from ...
3
votes
0answers
120 views

grep is inconsistently defaulting to grep -P?

I have a script that does some housekeeping that works perfectly well when invoked from an interactive shell, but did nothing when invoked by cron. To troubleshoot this I started a shell with a ...
3
votes
0answers
265 views

snmp MIB-TCP::tcp not showing any usage

I am trying to configure MRTG on all of my servers for making a network weathermap, this requires running SNMP which MRTG gets the information from. So, I installed it on two servers the exact same ...
3
votes
0answers
90 views

reprepro use when multiple sources have the same codename

I'm investigating the use of reprepro to control what updates get propagated to our servers, and when. The idea is to vet updates by Debian and Ubuntu, and only apply the ones we choose. We want to ...
3
votes
0answers
2k views

NAT64 configuration with tayga on Debian 6

I'm trying to implement NAT64 with tayga on my server and came to a point where I'm not sure how to proceed. My server is connected via one IPv4 address and one /64 IPv6 address block to the ...
3
votes
0answers
243 views

Samba4 locked pst files

i have a samba4 server that holds my clients outlook pst files, if the outlook client or the machine crashes i must go to the server to kill the PID manually. i saw there was "reset on zero vc =yes" ...
3
votes
0answers
797 views

Intermittent NFS lockups on Isilon cluster

We have an Isilon cluster with 8 IQ 12000x nodes which exports storage via several NFS shares for a handful of Linux and Solaris clients. There is a Linux system that has one of these NFS filesystems ...
3
votes
0answers
4k views

TCP Keepalive and firewall killing idle sessions

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 ...
3
votes
0answers
256 views

Monitoring Linux Kernel Space Processing

I'm running two "services" that are served in linux kernel-space: Linux Netfilter Firewall ("iptables") Linux Virtual Server Loadbalancer ("IPVS", "LVS") Now I want to (performance-)monitor my ...
3
votes
0answers
800 views

How do I configure OpenSwan to allow pure IPsec (not L2TP) connections from an iPhone?

Similar to this question, I want to configure an IPsec server on Linux which will accept connections from the iPhone. However, unlike the other question, I want to be able to test with pre-shared keys ...
3
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0answers
1k views

how to tune NFS client on MacOS to get Linux like performance?

I have a NFS server running Linux and exporting a couple of shares. Both Linux and MacOS clients connect to the server, and while with the Linux clients I get ~ 75MB/s write speed, the MacOS clients ...
2
votes
0answers
20 views

get notification when systemd-monitored service enters failed state

I need to have network messages sent when a systemd service I have crashes or is hung (i.e., enters failed state; I monitor for hung by using WatchdogSec=). I noticed that newer systemd have ...
2
votes
0answers
12 views

memory high issue on RHEL server?

18105 /wm/www/tmmy/ 2.2 1128256 1683020 16961 /usr/sbin/httpd 2.4 1201668 1692788 27746 /usr/sbin/httpd 2.4 1217296 1701612 31519 /usr/sbin/httpd ...
2
votes
0answers
49 views

How to find size of atomic write for nginx access log buffer?

This link says: The buffer size must not exceed the size of an atomic write to a disk file. For FreeBSD this size is unlimited. How can I find size of atomic write on my server? Is there any ...
2
votes
0answers
44 views

Issues getting systemd service to start (Jessie)

I've got a systemd service which I need to have run prior to networking having started and I'm struggling with it a little. According to this: Running Services After the Network is up I need to use ...
2
votes
0answers
32 views

Can pacemaker retry monitor action on error?

I created simple pacemaker agent for managing MySQL. It works quite well, but there is 1 thing that I can't understand. When resource is "Started", and monitor action returns one of: ...
2
votes
0answers
30 views

Linux iSCSI - Limit max concurrent sessions

I would like to understand if, and how to, limit the maximum number of simultaneous connections to a specific LUN under CentOS Linux, both with the old iSCSI stack (tgtadmin and friends) and the new ...
2
votes
0answers
40 views

Get statuses of network printers

we are tasked with finding exactly how many pages were printed by all IP printers on a fairly large network, and then doing a lot of things with that data. There are about 15 different printer ...
2
votes
0answers
46 views

Raid 1 seeding to speed up identical installs

I was thinking of installing Ubuntu on one of our Dell servers in a RAID 1 configuration, then using the mirrored drive as the primary drive in a second identical server with another RAID 1 setup. ...
2
votes
0answers
78 views

proc-sys-fs-binfmt_misc.automount failed service

I am using ubuntu 14.10. I have just installed systemd and I have a failing service, proc-sys-fs-binfmt_misc.automount. I've seen here it's a part of systemd: Is this file important? How do I solve ...
2
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0answers
106 views

elasticsearch fails periodically on ubuntu with systemd : how to resolve this?

I am using Elasticsearch on Ubuntu 14.10 and it's periodically going down (entering a failed state). When down, this throws exceptions on my website, users can't search, connect or update database ...
2
votes
0answers
36 views

Solving an asymetric HA Firewall/router

I have an old Linux HA firewall/router setup that never quite worked. As it was never quite put into true production (just testing and demo's), I always had to have one firewall shutdown to make it ...
2
votes
0answers
419 views

nginx recv() failed (104: Connection reset by peer) while reading response header from upstream

I have recently upgrade my magento from 1.5 to 1.9 and when ever I add a certain product to basket, I started to receive this error: 502 Bad Gateway There were no log entries in the var/log/ folder: ...
2
votes
0answers
133 views

Problems on mounted NFS: 'No such file or directory' but files and directories exist

So we are having a medium-sized NFS4 storage server running CentOS 6.6 exporting an NFS share /storageDat (which is the NFS root, with two RAID volumes bound in there: ./dat1 and ./dat2); Export ...
2
votes
0answers
118 views

php generated css no output, net::ERR_INCOMPLETE_CHUNKED_ENCODING

I am running apache on an ubuntu installation. Several webapps are running on the same server. I installed a new app, which required the pdo-sqlite extension to be installed. Now my server is ...
2
votes
0answers
48 views

Heroku and socket.io out of memory

I have a setup with websockets on heroku and every now and then i get a flurry of messages like this: 06:24.591694+00:00 heroku router - - at=error code=H15 desc="Idle connection" method=GET ...
2
votes
0answers
38 views

Move process across NUMA system

I am running many multi-threaded processes on a larger NUMA system with dozens of sockets. The memory access across different nodes is very slow, so I restrict each process to one socket and let it ...
2
votes
0answers
34 views

Dovecot and virtual domains with different namespaces

I've got dovecot 2.1.7 setup with virtual domains and now would like to have different public namespaces for each of the virtual domains. E.g. workdomain.com -> INBOX (private namespace) -> ...
2
votes
0answers
38 views

Tuning Amazon Linux worker tier

I have a worker tier that is using PHP process control (pcntl) functions to send multiple requests to the SNS service in parallel. My question is how best to tune MPM_PREFORK directives to get the ...
2
votes
0answers
58 views

NTP offset warning when no NTP server is defined and NTP not running?

I just want to preface by saying that I am still learning linux and don't have too much experience with it. My job requires me to monitor an alert system for our clients hosts that are running our ...
2
votes
0answers
60 views

Anomaly - Linux executables getting corrupted randomly

I am facing a strange problem with avconv which is a tool for processing videos part of libav-tools package. I am on a local ubuntu server 14.04.1 LTS. What happens is that the avconv tool is ...
2
votes
0answers
219 views

Using Rsnapshot with sync_first, link_dest, and use_lazy_deletes

I've set up rsnapshot with the configuration below and it seems to work fine. However, if I understand what I have read correctly, in the rsnapshot docs and other tutorials, the operation would be ...
2
votes
0answers
100 views

OpenLDAP TLS - test results in Bad file descriptor

I have set up an openldap server including tls on ubuntu 14.04 following this guide. While testing the connection, I get results that I can not find an explanation for. ldapsearch -xLLL -Z -W -D ...
2
votes
0answers
100 views

firewall-cmd forward rules for interface with multiple ips

I'm looking for a way with firewall-cmd or another command to do the following. An incoming public interface has multiple ip addresses bound to it. How can I forward ports only for one of the ip ...
2
votes
0answers
87 views

Linux NFS server refuses blocking locks

So I have this problem. This horrible, awful problem. I have a set of Linux NFS servers (in a NFS/CIFS cluster using CTDB) that refuse locks… only when the lock is blocking. If it's a non-blocking ...
2
votes
0answers
54 views

Git/svn - keeping synced two repositories with different access rights

I've been advised by @PatrickQuirk to post this question here... There is just too much information online for me to understand and be able to get my own picture, so I gently ask the community to ...
2
votes
0answers
45 views

IPsec - strange behavior

I have set up site-to-site ipsec connection between linux(debian) and mikrotik router. The tunnel is up linux configuration: config setup interfaces=%defaultroute keep_alive=60 ...
2
votes
0answers
1k views

Setting up a bootable multi-device (RAID 1) using Linux Software RAID

I'm trying to setup a bootable software RAID that will contain the root filesystem and boot up Linux Mint Qiana. It will be used to run a few graphical monitoring applications in a small datacenter, ...