Month: March 2015

i though i writing this down how i setup my own openvz nfs server container to serve as a NFS server. Installing it is pretty easy until a lot of errors start popping out when you try to start your openvz, so i though of just writing them down just in case.

To install openvz nfs server, all you need to do is

yum install nfs* -y

and all nfs library will be installed into your container. Next start everything!

 service rpcbind start
 chkconfig rpcbind on
 service nfs start
 chkconfig nfs on

And this is what i get,

Starting NFS services:                                     [  OK  ]
Starting NFS quotas:                                       [  OK  ]
Starting NFS mountd:                                       [  OK  ]
Starting NFS daemon: rpc.nfsd: Unable to access /proc/fs/nfsd errno 2 (No such file or directory).
Please try, as root, 'mount -t nfsd nfsd /proc/fs/nfsd' and then restart rpc.nfsd to correct the problem
                                                           [FAILED]

not too smooth journey as i though!

Different type of NFS errors

So there are a few kind of errors you will see when setting up an NFS server on Openvz container and you can see them on openvz.org NFS server article,

My issue was apparent this one,

If you see this:

# service nfs start
....
Starting NFS daemon: rpc.nfsd: Unable to access /proc/fs/nfsd errno 2 (No such file or directory).
Please try, as root, 'mount -t nfsd nfsd /proc/fs/nfsd' and then restart rpc.nfsd to correct the problem
                                                           [FAILED]
# mount -t nfsd nfsd /proc/fs/nfsd
mount: unknown filesystem type 'nfsd'
It means you haven't loaded nfsd kernel module on host before starting container.

Well...this means that i need to do more things!

Kernel NFS server

Kernel-space NFS server is supported by latest RHEL5 and RHEL6 based kernels and since vzctl-3.0.24. But currently only NFSv3 is supported - no NFSv4 support yet. More info here: http://forum.openvz.org/index.php?t=msg&goto=46174&. NFSv3 is notorious for leaving hanging file locks and in my opinion NFSv3 should not be used in file intensive setups. So that's the thing i will need to live with for the time being.

NFS Openvz Prerequisites

In order to run an NFS server inside a container, make sure:

• nfsd kernel module is loaded on host system before starting a container
• nfsd feature for a container is turned on

Setup

• Make sure that rpcbind service is started before nfs service:

chkconfig rpcbind on && service rpcbind start

• Disable NFSv4 and nfsd module loading warnings in /etc/sysconfig/nfs by uncommenting the following lines:

MOUNTD_NFS_V3="yes"
RPCNFSDARGS="-N 4"
NFSD_MODULE="noload"

• Start NFS service:

chkconfig nfs on && service nfs start

Host node

Once you done that, remember to activate NFS inside a container issue the command below

vzctl set $CTID --feature nfsd:on --save

and ensure modules nfs and nfsd is loaded:

modprobe nfsd
modprobe nfs

All you left to do is to start your container and see whether the error is eliminated. If its still doesn't work, check out this forum thread where most of the information above are retrieved (credit goes to them).

*****UPDATE******

Opps, i forget. On /etc/exports u need to state the directory that you want people to be able to use your nfs to mount their machine on, in my case it's /mnt/nfs so i did this,

mkdir -p /mnt/nfs

then on /etc/exports i did this

/mnt/nfs     192.168.0.0/24(rw,no_root_squash,no_subtree_check,fsid=0)

take note that 192.168.0.0/24 is the range of ip that will mount my nfs directory.

Firewall Host

After everything is done up there, just remember to update your firewall to allow nfs port to your nfs server. On the path /etc/sysconfig/nfs open it up and update all the path and uncomment LOCKD_TCPPORT, MOUNTD_PORT, STATD_PORT and LOCKD_UDPPORT and allow the port as written below, ( and you will notice this is done on a Centos machine)

1. Allow TCP and UDP port 2049 for NFS.
2. Allow TCP and UDP port 111 (rpcbind/sunrpc).
3. Allow the TCP and UDP port specified with MOUNTD_PORT="port"
4. Allow the TCP and UDP port specified with STATD_PORT="port"
5. Allow the TCP port specified with LOCKD_TCPPORT="port"
6. Allow the UDP port specified with LOCKD_UDPPORT="p

and in case you need the iptables command, here you go, and you are welcome

-A PREROUTING -d 10.6.25.101/32 -i vmbr0 -p tcp -m tcp --dport 2925 -j DNAT --to-destination 192.168.0.111:22
-A PREROUTING -d 10.6.25.101/32 -i vmbr1 -p tcp -m tcp --dport 32803 -j DNAT --to-destination 192.168.0.111:32803
-A PREROUTING -d 10.6.25.101/32 -i vmbr1 -p tcp -m tcp --dport 892 -j DNAT --to-destination 192.168.0.111:892
-A PREROUTING -d 10.6.25.101/32 -i vmbr1 -p tcp -m tcp --dport 662 -j DNAT --to-destination 192.168.0.111:662
-A PREROUTING -d 10.6.25.101/32 -i vmbr1 -p tcp -m tcp --dport 2049 -j DNAT --to-destination 192.168.0.111:2049
-A PREROUTING -d 10.6.25.101/32 -i vmbr1 -p tcp -m tcp --dport 111 -j DNAT --to-destination 192.168.0.111:111
-A PREROUTING -d 10.6.25.101/32 -i vmbr1 -p udp -m udp --dport 892 -j DNAT --to-destination 192.168.0.111:892
-A PREROUTING -d 10.6.25.101/32 -i vmbr1 -p udp -m udp --dport 662 -j DNAT --to-destination 192.168.0.111:662
-A PREROUTING -d 10.6.25.101/32 -i vmbr1 -p udp -m udp --dport 111 -j DNAT --to-destination 192.168.0.111:111
-A PREROUTING -d 10.6.25.101/32 -i vmbr1 -p udp -m udp --dport 2049 -j DNAT --to-destination 192.168.0.111:2049
-A PREROUTING -d 10.6.25.101/32 -i vmbr1 -p udp -m udp --dport 32769 -j DNAT --to-destination 192.168.0.111:32769
-A PREROUTING -d 10.6.25.101/32 -i vmbr1 -p tcp -m tcp --dport 8000 -j DNAT --to-destination 192.168.0.111:8000

just port forwarding for both up and tcp 😉

and remember to open up all the port at /etc/sysconfig/nfs

#
# Define which protocol versions mountd
# will advertise. The values are "no" or "yes"
# with yes being the default
#MOUNTD_NFS_V2="no"
MOUNTD_NFS_V3="yes"
#
#
# Path to remote quota server. See rquotad(8)
#RQUOTAD="/usr/sbin/rpc.rquotad"
# Port rquotad should listen on.
#RQUOTAD_PORT=875
# Optinal options passed to rquotad
#RPCRQUOTADOPTS=""
#
#
# Optional arguments passed to in-kernel lockd
#LOCKDARG=
# TCP port rpc.lockd should listen on.
LOCKD_TCPPORT=32803
# UDP port rpc.lockd should listen on.
LOCKD_UDPPORT=32769
#
#
# Optional arguments passed to rpc.nfsd. See rpc.nfsd(8)
# Turn off v2 and v3 protocol support
#RPCNFSDARGS="-N 2 -N 3"
# Turn off v4 protocol support
RPCNFSDARGS="-N 4"
# Number of nfs server processes to be started.
# The default is 8.
#RPCNFSDCOUNT=8
# Stop the nfsd module from being pre-loaded
NFSD_MODULE="noload"
# Set V4 and NLM grace periods in seconds
#
# Warning, NFSD_V4_GRACE should not be less than
# NFSD_V4_LEASE was on the previous boot.
#
# To make NFSD_V4_GRACE shorter, with active v4 clients,
# first make NFSD_V4_LEASE shorter, then restart server.
# This will make the clients aware of the new value.
# Then NFSD_V4_GRACE can be decreased with another restart.
#
# When there are no active clients, changing these values
# can be done in a single server restart.
#
#NFSD_V4_GRACE=90
#NFSD_V4_LEASE=90
#NLM_GRACE_PERIOD=90
#
#
#
# Optional arguments passed to rpc.mountd. See rpc.mountd(8)
#RPCMOUNTDOPTS=""
# Port rpc.mountd should listen on.
MOUNTD_PORT=892
#
#
# Optional arguments passed to rpc.statd. See rpc.statd(8)
#STATDARG=""
# Port rpc.statd should listen on.
STATD_PORT=662
# Outgoing port statd should used. The default is port
# is random
#STATD_OUTGOING_PORT=2020
# Specify callout program
#STATD_HA_CALLOUT="/usr/local/bin/foo"
#
#
# Optional arguments passed to rpc.idmapd. See rpc.idmapd(8)
#RPCIDMAPDARGS=""
#
# Set to turn on Secure NFS mounts.
#SECURE_NFS="yes"
# Optional arguments passed to rpc.gssd. See rpc.gssd(8)
#RPCGSSDARGS=""
# Optional arguments passed to rpc.svcgssd. See rpc.svcgssd(8)
#RPCSVCGSSDARGS=""
#
# To enable RDMA support on the server by setting this to
# the port the server should listen on
#RDMA_PORT=20049

Firewall Guest

Remember to turn off or allow those port to your guest as well if you are on Centos.

chkconfig iptables off
service iptables stop

i prefer to off it entirely.

Appendix

• https://www.howtoforge.com/setting-up-an-nfs-server-and-client-on-centos-6.3
• http://forum.proxmox.com/threads/9509-NFS-inside-OpenVZ-container
• http://www.unixmen.com/nfs-server-installation-and-configuration-in-centos-6-3-rhel-6-3-and-scientific-linux-6-3/
• https://openvz.org/NFS_server_inside_container
• http://www.linuxquestions.org/questions/linux-server-73/nfs-share-setup-issue-mountd-refused-mount-request-unmatched-host-924105/
• https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/s2-nfs-nfs-firewall-config.html

Ok, so i don't want to waste my IP addresses so i would need to setup multiple openvz container with private ip with a single host public ip. If you did read the article on openvz.org about using NAT for container with private IPs, but you were unable to setup properly or your internet isn't going into your container, this is most likely due to a setup issue you have (which is what happen to me and this is why i am writing this up!)

Assuming i have 3 container with the following ips (please setup these ips on your containers)

vps1.hungred.com 192.168.0.1
vps2.hungred.com 192.168.0.2
vps3.hungred.com 192.168.0.2

and a single public ip host machine that all these 3 containers sites on with the following ip

vps.hungred.com 10.2.5.1

i am going to setup and explain what is going to be done with the above machines.

OpenVZ Host

Most of the work, or to be exact, all of the work will need to be done on the Openvz Host machine in this case its the machine with the ip 10.2.5.1. Make sure the following things are done on your host machine,

IP forwarding should be turned on on the hardware node in order for container networking to work. Make sure it is turned on:

$ cat /proc/sys/net/ipv4/ip_forward
1
Output should be '1'. If it is '0', enable IP forwarding as it is described in Quick installation#sysctl.

NOTE: Ubuntu made some changes to the syntax for NAT. See this link if you are needing to enable NAT on an Ubuntu host :

Launchpad

The syntax of /etc/sysctl.conf has changed to :

net.ipv4.conf.default.forwarding=1
net.ipv4.conf.all.forwarding=1

Once the above are done, it's time to setup our iptables to forward all internet traffic to our containers. All you need to do are to setup the iptables with the range of ips needed to forward to.

To enable the containers, which have only internal IP addresses, to access the Internet, SNAT (Source Network Address Translation, also known as IP masquerading) should be configured on the Hardware Node. This is ensured by the standard Linux iptables utility. To perform a simple SNAT setup, execute the following command on the Hardware Node:

# iptables -t nat -A POSTROUTING -s src_net -o eth0 -j SNAT --to ip_address
where src_net is a range of IP addresses of containers to be translated by SNAT, and ip_address is the external IP address of your Hardware Node. The format of src_net is xx.xx.xx.xx/xx (CIDR notation). For example:

# iptables -t nat -A POSTROUTING -s 192.168.2.0/24 -o eth0 -j SNAT --to ip_address
Multiple rules are allowed, for example, in case you wish to specify several ranges of IP addresses. If you are using a number of physical network interfaces on the Node, you may need to specify a different interface for outgoing connections, e.g. -o eth2.

To make all IP addresses to be translated by SNAT (not only the ones of containers with private addresses), you should type the following string:

# iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to ip_address

Let me explain a little bit on what is really needed, you will really want to enter the below statement

iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -o eth0 -j SNAT --to 10.2.5.1

what the above does is to tell your iptables to allow all private ip of the range 192.168.0.1-192.168.254 to be connect to the internet at 10.2.5.1 but bear in mind what ethernet port you are using, it can be eth0 or vmbr01 depending what you have setup your 10.2.5.1 on. Just firing up ifconfig and you should see where 10.2.5.1 are being attached to.

and also, while you are still at it, do setup your firewall as well.

Firewall
For Debian hardware node, you may need to allow a forward rule. The table still being the default table (filter) but the chain is FORWARD:

# iptables -A FORWARD -s 192.168.0.0/24 -j ACCEPT
# iptables -A FORWARD -d 192.168.0.0/24 -j ACCEPT
For default RedHat/CentOS firewall, allow outgoing connections from your containers, for example:

# iptables -A RH-Firewall-1-INPUT -s 192.168.0.0/24 -j ACCEPT
# iptables-save > /etc/sysconfig/iptables
# service iptables restart

The above forward all internet and accept connection from the range of 192.168.0.1-192.168.254 due to /24 being accepted.

Once you are done with the above, test it out

Test
Now you should be able to reach internet from your container:

# vzctl exec $CTID ping openvz.org

where $CTID is the openvz id

if you don't get unknown host, and get a response back, you have just setup your machine with an internal ip!