Virutal Machine And CentOS

[My220x]

I am going to install a VM software and run CentOS but the thing is how much RAM would I need to allocate it as I plan to only use the CLI?

[penfold_99]

It will depend on what vm software you are using and what os your have on your host machine.

[dhicks]

I am going to install a VM software and run CentOS but the thing is how much RAM would I need to allocate it as I plan to only use the CLI?

 

Well, what does the documentation for CentOS suggest that its minimum RAM requirements are? I have some Ubuntu VMs running with 192MB of RAM allocated, if that's any help - you can always try simply creating a VM with 192MB of RAM and see if CentOS runs in it. Do you need to use CentOS, could you use a smaller distribution - Ubuntu, or one of the ultra-small distros like Damn Small, System Rescue CD, etc?

 

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David Hicks

[budgester]

Runnig debian VM with 128mb ram for a basic webserver

[My220x]

I was thinking of running CentOS with 256MB Ram as I have 1GB RAM giving me 744MB left giving me 232MB more than Vista reccomended.

[kmount]

On top of Vista? Ouch, I think that'll scream with only 1GB.

[My220x]

Well, centos needs 512MB for full version but could I run it on 128?

[kmount]

Can't see why not, the basic rule of thumb would be the less resources you allocate, the poorer it would perform.

[My220x]

The thing is I am not going to use the GUI just be working via the shell.

[powdarrmonkey]

You can run it on 128Mb but I've had problems with yum not being able to allocate enough resources during updates. 256Mb is safer.

[My220x]

Ok, I will use 256MB, do you think Vista will be ok on the RAM left as I only have 1GB.

[powdarrmonkey]

If you're patient with it.

[My220x]

I will only be using Vista to read the tut while working.

[My220x]

I now have it all setup and have installed ssh software but how do I connect via Putty? I typed ifconfig in a terminal and got the inet addr for eth0 but I tried to connect using it via Putty and got nothing.

[powdarrmonkey]

Firewall? (iptables -L)

[kmount]

Tried ssh localhost to ensure SSH is running?

[dhicks]

I now have it all setup and have installed ssh software but how do I connect via Putty? I typed ifconfig in a terminal and got the inet addr for eth0 but I tried to connect using it via Putty and got nothing.

 

How did you install SSH on the virtual server? I know when I install CentOS on our servers I don't have to specifically check an "install SSH" option, it seems to be part of the "server" package setup. Firewall exceptions are automatically made, too. Are you sure your VM is actually connected to your network (what virtual machine system are you using, anyway?)? Try pinging Google or something from your virtual machine instance, see if it can actually connect to the outside world.

 

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David Hicks

[My220x]

I actually ended up installing Ubuntu and I installed ssh via the shell using apt-get install and I can connect to the internet via my Virtual Machine and I am using VM Box or something. Also, I can now SSH into it but I now get a time out error.

[dhicks]

I actually ended up installing Ubuntu and I installed ssh via the shell using apt-get install and I can connect to the internet via my Virtual Machine and I am using VM Box or something. Also, I can now SSH into it but I now get a time out error.

 

"VM Box or something" - you mean you're using VMWare, right?

 

"I can now SSH into it but I now get a time out error" - you mean the SSH server is running on the virtual machine (as suggested above, on the virtual machine itself you can type "ssh localhost" and connect okay, right?) but you can't actually connect to it from your physical machine? You know the network interface is up, though, as you can ping external addresses from your virtual machine. I would guess firewall again - either the firewall on your virtual machine needs to be configured to allow SSH connections in, or your physical machine needs to be configured to let SSH connections out.

 

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David Hicks

[My220x]

Would I type ssh localhost into the linux terminal? I havent tried this so when I get home I will.

[kmount]

Yes ... because you are trying to SSH into the local machine.

[My220x]

Ok, cool , will do that when I get home and if I can do that what would I do next?

[kmount]

If that works, you have proven that SSH is working correctly on the local machine and that the problem lies elsewhere.

 

On the Linux box, run /sbin/ifconfig (or just ifconfig depending on the path setup) and note down the information into a file and post it here.

 

Example

[root@frisky ~]# ifconfig

eth1 Link encap:Ethernet HWaddr 00:D0:B7:B9:85:63

inet addr:10.12.112.18 Bcast:10.12.115.255 Mask:255.255.252.0

inet6 addr: fe80::2d0:b7ff:feb9:8563/64 Scope:Link

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:4751024 errors:0 dropped:0 overruns:0 frame:0

TX packets:424780 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:573642789 (547.0 MiB) TX bytes:89566592 (85.4 MiB)

Memory:feae0000-feb00000

 

The theory would be that whatever IP is has can be SSH'd into from your PC but it wholly depends on how you've created the VM, i.e. bridged networking or whatnot.

 

If you're definitely certain on the network address front, you need to look for firewall implications, again on the linux box, type iptables -L and see what it says.

[dhicks]

Ok, cool , will do that when I get home and if I can do that what would I do next?

 

If, from the Linux command line prompt of your virtual machine, you can type "ssh localhost" and get an open SSH connection then that means that the SSH server (SSHD) is running on your virtual machine. You also know that the (virtual) network interface is working as you can type something like "ping www.google.co.uk" and get a response. Therefore, if you still can't connect from your physical machine to your virtual machine, the most likely (?) problem is something to do with your firewall - either the firewall on your virtual machine needs to be configured to allow SSH connections in, or your physical machine needs to be configured to let SSH connections out.

 

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David Hicks

[dhicks]

The theory would be that whatever IP is has can be SSH'd into from your PC but it wholly depends on how you've created the VM, i.e. bridged networking or whatnot.

 

Oh yea, good point - the two machines could be on different subnets or something. Could also add try and ping the virtual machine from the physical one (i.e. open up command prompt in Windows, type "ping IPaddress.of.virtual.machine" and see what happens), just to make sure they can actually see each other.

 

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David Hicks