I wish to allocate vSwap memory to my OpenVZ containers. Where does OpenVz get the vSwap memory from? If the host were to run out of physical RAM, would the host start to use its own normal swap memory?
I ask this as I am using SSDs in our host server, which while not as fast as proper RAM, are still loads faster than spindle disks, so using normal swap space from these SSDs wouldn't be the worst thing in the world.
Many Thanks
I have a script that issues a lot of commands. I wish to save the output of this script (Errors and stdout) to a file, but I also want the actual commands that were executed to be saved to the file as well (as displayed by bash -x)
I've tried:
bash -x script.sh > log.txt
to no avail
Any help is appreciated. Thanks
I'm sorry if this sounds like a silly question, but when I compile something on linux using the usual "./configure, make, make install" steps, how can I install the programs on other servers without having to recompile?
I am trying to avoid having to install the build tools on production servers, however I need the latest version of a particular piece of software, so using RPMs isn't an option in this case.
Any help is appreciated.
Thanks
I'm using CentOS 5. I have a need to use net-snmp version "net-snmp-utils-5.5-37.el6_2.1.x86_64" which is currently available in CentOS 6 but not in CentOS 5. The reason I need this version (or greater) is because there is a new supported option added to the config files that I need for my setup.
It would be very much appreciated if someone would give me some steps to install this version (or greater) on my production CentOS 5 systems. Upgrading to CentOS 6 is currently not an option.
Any help would be appreciated.
Thanks
We wish to install some servers in a remote datacentre to act as a backup storage location for our primary datacentre.
Assuming that both sites will have GigE connectivity, what is the best method to use for fast file transfer? I love rsync, however since we have a lot of data to transfer (1.5TB per night), I think that the SSH protocol used in rsync may slow things down a lot :(
We could install some fast VPN endpoints to cater for link encryption, however the question still stands: what is the best tool for the actual transfer?
If we were to connect two switches together using LACP (with 2 X 1Gbe ports on each side), does this mean that the max speed that a single MAC address will ever reach is 1Gb?
So for example, if a single MAC address decided to "abuse" the link (e.g. DoS attack) and saturate their connection, does this mean that their traffic will only ever flow down a single link, leaving the other MACs free to travel down the other?
Thanks
We host VPSes for customers. Each customer VPS is given an LVM LV on a standard spindle hard disk. If the customer were to leave, we zero out this LV ensuring that their data does not leak over to another customers.
We are thinking of going with SSDs for our hosting business. Given that SSDs have the "wear levelling" technology, does that make zeroing pointless? Does this make this SSD idea unfeasable, given we can't allow customer data to leak over to another customer?
At the minute, we host VPSes for many customers using standard RAID10 setups using spindle hard disks.
We are thinking of trying a new experiemnt: SSD based VPSes in RAID10 arrays.
My knowledge isn't very clear on SSDs in high read/write environments such as VPS hosting for multiple customers.
Would SSDs simply fail in this way? I've heard some bad things about SSDs...
Any tips would be appreciated
I have an LVM logical volume (LV) and would like to create partitions within this LV to provide an ext3 partition and a swap partition. This LV would then get mounted as a disk to a virtual machine (Using Xen).
How would I go about this?
Thanks
I make heavy use of Linux Bridges (brctl) as I have a Xen environment. At the minute, only one physical NIC is connected to the bridge (There are many virtual NICs for the Xen VMs though). In order to get some redundancy working, what steps would I need to take to add another physical NIC to the bridge? This second NIC will be connected to a different switch. Do I need to run a cable between the 2 switches and enable STP?
Please note that the NIC do not have IP assigned to them (however the bridges do).
I do know the commands to add NICs to bridges; my question related to the redundancy aspect of it.
I am about to implement an iSCSI solution on our network. The thing that is bothering me though is that we are only using 1 switch from the SAN to node connections. Since each node has 2 NICs, is anyone able to give me some tips on how to set up a second switch and use the second NIC in such a way that if the first switch were to die, then the second switch would take over?
Maybe in any case, even if there was a failover solution, would data loss still occur due to the "switch over" time required?
O/S is Centos 5.5
I'm looking for a good free method of logging IP heading information (src/dest IP with timestamp) passing through a Linux router.
I know I can do this with
tcpdump -i eth0 > log.txt
However I'm looking for something a bit more substantial, as this will be running all the time.
I will have 2 Postfix servers. One will be a backup of the other.
What is the easiest method to provide central storage to both of these boxes? My infrastructure is very simple: Just a lot of Xen hosts, so there is no SAN or anything.
Each Xen host does have RAID1 though.
I don't mind mounting NFS shares on each of those mail servers, as long as the NFS server wasn't a single point of failure. Is there such a thing as redundant NFS?
Any help would be appreciated
Thanks
I wish to host some managed email servers for some customers. Each customer will have their own email server which will be an all-in-one virtual machine running postfix, dovecot and some webmail suite.
Even though each customer will have their own server, I do not wish to give each email server it's own public facing IP. I wish to avail the use of proxy servers so all customers use the same public IP. As for the "smtp-in" from the public internet, this isn't a problem as I can set up many mx servers (using postfix) which will store-and-forward the mail to the correct server (using transport maps). As for the IMAP access from the customer, I was thinking of using perdition which is an IMAP proxy - I believe that this will suit my needs.
I am confused however on what to use for the "smtp-out" proxy. The customers will have to authenticate with their receptive email server, however they will have to go via a proxy of some sort as they won't have direct access to their server instance. It probably can't be a store-and-forward proxy either.
Does anyone have any idea on what I could use here?
Many Thanks
As per title, why do people tell me not to use VLANs for security purposes?
I have a network, where a have a couple of VLANS. There is a firewall between the 2 VLANs. I am using HP Procurve switches and have made sure that switch-to-switch links accept tagged frames only and that host ports don't accept tagged frames (They are not "VLAN Aware"). I've also made sure that the native VLAN (PVID) of the trunk links are not the same as either of the 2 host VLANs. I've also enabled "Ingress Filtering". Furthermore, I've made sure that host ports are only members of a single VLAN, which is the same as the PVID of the respective port. The only ports which are members of multiple VLANs are the trunk ports.
Can someone please explain to me why the above isn't secure? I believe I've addressed the double tagging issue..
Thanks
Update: Both switches are Hp Procurve 1800-24G
I have a potential customer who wants a hosted managed backup solution. Their server is running Windows.
Does anyone know of any software (open source is preferred, but free for commercial use is ok) that will allow me to make incremental backups from a Windows server to a remote Linux box? Restoring files should be easy as well. I also need built-in encryption
Cheers
We've developed a client/server solution using Java RMI. We wish to know the amount of data being transfer over the wire from server to client so we can judge bandwidth requirements.
I've created a capture of the traffic using wireshark, however is there a way to find the total size of all the packets?
If wireshark isn't the best solution, can someone please suggest a better application?
Thanks
I wish to set up a new website that will be accessed by users using HTTPS. I think it is good practise to put the "real" web server in a seperate subnet, and then install an Apache Reverse Proxy in a DMZ.
My question is, where should I put the SSL cert(s)? Should I
a) Use a self-signed cert on the "real" web server, and a proper cert on the reverse proxy?
b) Use 2 real certs on both the "real" web server and the reverse proxy?
c) Don't use any cert on the "real" web server, and use a proper cert on the reverse proxy?
I'd like to use a) or c), if possible. I also don't want anyone's browser complaining of a self-signed cert.
Thanks
With Ajaxterm (http://antony.lesuisse.org/software/ajaxterm/), is it safe to allow multiple users to access the same "instance" of it? The program that Ajaxterm would run would do its own authentication.
Not sure if anyone here has used Ajaxterm before, however I'm posting here on the off chance that someone has experience in this area.
Thanks
Is it possible to somehow setup an ssh server that doesn't require a username,password or cert to login? If that's not possible, if I were to give all customers the same public key, would each connection be encrypted individually? (i.e. user A coudn't decrypt the payload of user B's connection)
I wish to provide access to a single program, which will prompt for a username and password.
Encryption is essential though, and users must not be able to snoop in on each other
Thanks