klew's questions

I have four computers and on two of them (say it will be n1 and n2) I have installed NFS4 server and exported:

/export   10.0.0.0/16(rw,fsid=0,no_subtree_check,async,insecure,no_root_squash)
/export/home 10.0.0.0/16(rw,fsid=0,no_subtree_check,async,insecure,no_root_squash)

Now, both n1 and n2 has the same configuration and I can mount and unmount those resources on any of my computers (in /home/n1 and /home/n2) without errors, but I can access only resources from n1. When I try to ls directory from n2 I get error: "Stale NFS file handle".

My network is working correctly, I have no firewall, both of them has the same configuration and the same Ubuntu 10.04 server version.

On client machines in logs I get this error:

[585039.584017] NFS: server 10.0.1.4 error: fileid changed
[585039.584019] fsid 0:16: expected fileid 0x1ba54e2, got 0x3f20001

I've checked it on server machine and this 0x3f20001 is id of /export directory and 0x1ba54e2 is /export/home.

My fstab looks like this:

10.0.1.4:/home /home/n2 nfs4    _netdev,auto 0 0

IP 10.0.1.4 belongs to n2 host.

Any idea?

I have four computers that have nonlocal addresses like 150.X.X.X. Now I also get another few computers that should be only accessible through a gateway (it will be computing cluster) and they addresses are 10.0.0.X. I also wanted to include those four older computers to this new cluster, but I want them to be accessible from internet on nonlocal addresses (so I would like to set up them on both 150.X.X.X and 10.0.0.X addresses - I've set up it as interface eth0:0 since I have only one NIC).

Those new computers have their switch and old computers also have their own switch. Both of them are connected to another (third) switch.

The problem is that those old computers see each other (I can ping them), and also new computers see each other, but I can't ping old computer from new computer and vice versa. However pinging on nonlocal adresses works as expected.

I looked into switch configuration and didn't find anything useful.

I have no idea what I missed here. Can somebody help?

All computers have Ubuntu Server 10.04

I've just changed default motd in Ubuntu (I edited /etc/update-motd.d/* files) and added some string in polish:

echo "Aby uzyskać dodatkowe informacje i przykładowe skrypty wpisz:"

but autogenerated /etc/motd is without accent characters:

Aby uzyska dodatkowe informacje i przykadowe skrypty wpisz:

So "ć" and "ł" is missing. So how to enable utf-8 encoding in motd?

I'm using Ubuntu 10.04 and trying to install Sun Grid Engine from Ubuntu repesitory. It works on single machine, I can submit jobs etc. But I can't make it working with any other machine. I added another execution host and installed gridengine-client gridengine-common gridengine-exec but it somehow can't communicate with master. I even turned off all firewalls to make sure it isn't causing a problem.

When I try qstat -f on master node I get:

queuename                      qtype resv/used/tot. load_avg arch          states
---------------------------------------------------------------------------------
standard@neuron1               BIP   0/0/2          0.04     lx26-amd64    
---------------------------------------------------------------------------------
standard@neuron2               BIP   0/0/2          -NA-     -NA-          au

When I restart deamon on neuron2 node I get:

error: can't find connection
error: can't get configuration from qmaster -- backgrounding

When I try to run qstat -f from n2 (neuron2) node I get:

error: commlib error: access denied (server host resolves destination host "n1" as "neuron1")
error: unable to contact qmaster using port 6444 on host "n1"

I have two hostnames for this machine and it looks like the first error has something to do with it, but it would be strange if it is causing this kind of problem. I tried telnet n1 6444 and it connects.

Does anybody know what is going on here? Am I missing something?

I'm new to LDAP and I already configured accounts with LDAP so I can login on few computers with LDAP.

Now I would like to add some host names to LDAP. In /etc/nsswitch.conf I changed:

hosts:          files dns ldap

But I have no idea how to add anything to LDAP database so it could resolve some names. I tried google but I couldn't find anything helpful.

On example, how to add this:

192.168.1.1    node1

I have a web service on address example.com and I add some functionality to it using completly separate web application set on different host. I want to set a subdomain another.example.com to open my new application. So by now I have two host providers and another one who maintain my domain.

I want another.example.com to be encrypted: https://another.example.com. So I need to buy a certificate and install it. What do I need to do? Where it should be installed? Which server should be configured to use it? My second host provider or that with domain? Do I need to reconfigure my domain?

Can someone explain it to me? I'm a little bit confused right now.

I have two computers connected in network and I would like them to share my home directory. I thought of mounting on one of them home directory from another computer.

I may happen that one of those computers is off, so it should remount home directory when it is possible (or on access).

I prefer encrypted solution (sshfs?)

I will need this directory to run some parallel programs that should access files in home directory, so it should be reliable - is sshfs good for this? Or should I look for something else?

I'm using Ubuntu, but other Linux solutions are welcome.

I have computer with Ubuntu behind router that I can't configure. However I want to have ssh access to that computer. I think it is possible with ssh tunneling, but I don't know how to do it. I have another server to which I would like to setup tunneling. How to do it? Or maybe you have some other idea how to solve this problem?

I tried:

ssh -N user@my_server -L 22/localhost/8090

but it says:

bind: Address already in use
channel_setup_fwd_listener: cannot listen to port: 22
Could not request local forwarding.

Could somebody give some simple steps with configuration example how to setup simple firewall on Ubuntu (using console only)? Only ssh, http and https access should be allowed.