SupportSages

Since we are in the field of VPS hosting technical support we know the importance of firewall in a VPS.So that the blog is intended to provide the steps to enable iptables in a VPS.

Before trying to enable iptable modules on the VPS, make sure that those modules are enabled on the root node server. To check whether the particular iptable modules are enabled or not on the root node, execute the following command.

lsmod

A Sample out put for the lsmod is :

Module                  Size  Used by
xt_helper              35584  0
ip_conntrack_ftp       42320  2
ipt_LOG                39808  0
ipt_owner              34944  0
ipt_REDIRECT           34944  0
ipt_recent             43404  2
xt_state               35200  5
sch_sfq                38912  1
cls_u32                41352  1
sch_cbq                50688  1
ppp_deflate            39168  0
zlib_deflate           52760  1 ppp_deflate
ppp_async              45184  0
ppp_generic            62624  2 ppp_deflate,ppp_async
slhc                   39552  1 ppp_generic
crc_ccitt              35200  1 ppp_async
tun                    47872  0
vzethdev               47264  0
simfs                  38296  36
vzrst                 173096  0
vzcpt                 148792  0
vzdquota               78832  36 [permanent]
xt_tcpudp              36224  21
xt_length              34944  0
ipt_ttl                34816  0
xt_tcpmss              35328  0
ipt_TCPMSS             37248  0
iptable_mangle         37888  36
xt_multiport           36224  0
xt_limit               36352  4
ipt_tos                34560  0
ipt_REJECT             39556  1
iptable_nat            43532  46
ip_nat                 53392  3 ipt_REDIRECT,vzrst,iptable_nat
iptable_filter         37760  42
ip_conntrack          100884  29 xt_helper,ip_conntrack_ftp,xt_state,vzrst,vzcpt,iptable_nat,ip_nat
nfnetlink              40392  2 ip_nat,ip_conntrack
ip_tables              57440  3 iptable_mangle,iptable_nat,iptable_filter
x_tables               52744  17 xt_helper,ipt_LOG,ipt_owner,ipt_REDIRECT,ipt_recent,xt_state,xt_tcpudp,xt_length,ipt_ttl,xt_tcpmss,ipt_TCPMSS,xt_multiport,xt_limit,ipt_tos,ipt_REJECT,iptable_nat,ip_tables
autofs4                57480  2
hidp                   83584  2
rfcomm                105000  0

Here we can see most of the modules are already enabled on the node server. If not enabled, execute the following commands one by one to enable those.

modprobe ipt_helper
modprobe ipt_REDIRECT
modprobe ipt_state
modprobe ipt_TCPMSS
modprobe ipt_LOG
modprobe ipt_TOS
modprobe iptable_nat
modprobe ipt_length
modprobe ipt_tcpmss
modprobe iptable_mangle
modprobe ipt_limit
modprobe ipt_tos
modprobe iptable_filter
modprobe ipt_helper
modprobe ipt_tos
modprobe ipt_ttl
modprobe ipt_REJECT
modprobe ipt_helper
modprobe ipt_owner

Next step is to enable these modules on the VPS.

Stop the container first :  vzctl stop 960 ( replace 960 with the concerned VPS ID )

Execute the following command :

vzctl set 960 –iptables ipt_REJECT –iptables ipt_tos –iptables ipt_TOS –iptables ipt_LOG –iptables ip_conntrack –iptables ipt_limit –iptables ipt_multiport –iptables iptable_filter –iptables iptable_mangle –iptables ipt_TCPMSS –iptables ipt_tcpmss –iptables ipt_ttl –iptables ipt_length –iptables ipt_state –iptables iptable_nat –iptables ip_nat_ftp –iptables ip_conntrack_ftp –iptables ip_conntrack_irc –iptables ip_nat_irc –iptables ipt_owner –iptables ipt_helper –save

Start the container : vzctl start 960

check whether the modules are enabled from the configuration file cat /etc/vz/conf/960.conf. You are DONE.

Please note that if the command “vzctl set 960 –iptables ipt_ ….” is executed for the second time for the same VPS, it will over write the previous configuration.

For enabling it on all VPSes, please add to /etc/sysconfig/vz all those modules like IPTABLES=”module1 module2 ….etc”