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--- cluster:102 [2011/06/29 09:58]
hmeij
+++ cluster:102 [2020/08/24 07:19] (current)
hmeij07
@@ Line 2: / Line 2: @@
 **[[cluster:0|Back]]**
-This is my second NAT story, for the first one look at [[cluster:51|The Story Of NAT, part 1]]
+Note #1
+CentOS 8.1 with the standard firewalld.\\
+If this is of interest to you this was how I managed to get it work:
+<code>
+EXTIFACE=MASTER_NODE_EXT_INTERFACE_DEVICE (e.g. eno1)
+INTIFACE=MASTER_NODE_INTERNAL_INTERFACE_DEVICE (e.g. eno2)
+INTIPADDR=MASTER_IP_OF_INTERNAL_IFAC
+PREFIX=PREFIX_OF_INTERNAL_NETWORK
+firewall-cmd --change-interface=${EXTIFACE} --zone=public
+firewall-cmd --change-interface=${INTIFACE} --zone=trusted --permanent
+firewall-cmd --permanent --direct --passthrough ipv4 -t nat -I POSTROUTING -o ${EXTIFACE} -j MASQUERADE -s ${INTIPADDR}/${PREFIX}
+firewall-cmd --set-default-zone=trusted
+firewall-cmd --reload
+</code>
+And make sure the default route is set on all compute nodes.
+Note #2
+configured Shorewall on a cluster to do NAT through the head node.
+Edit the file /etc/shorewall/snat   and add this line:
+<code>
+MASQUERADE 192.168.0.0/24      eno1
+</code>
+where 192.168.0 is the address range of your node interfaces - clearly you need to change this to fit
+en01 is the external interface on the head node
+My /etc/shorewall/interfaces contains this (forwarding ib0)
+<code>
+nat     eno1    detect  dhcp
+nat     ib0     detect  dhcp
+</code>
+so substitute ib0 for your internal ethernet interface
 ==== NAT Story, part 2 ====
+This is my second NAT story, for the first one look at [[cluster:51|The Story Of NAT, part 1]]
 Writing this up so I will remember what I did, and why.  Basic problem is this: How do you make a filesystem in a public VLAN available on a private network?  One solution is to work with Network Address Translation, or NAT in short.  More information at [[http://en.wikipedia.org/wiki/Network_address_translation|http://en.wikipedia.org/wiki/Network_address_translation]]
+We have a storage device which we refer to as flexstorage.wesleyan.edu which serves up a file system on login node petaltail.
+<code>
+[root@petaltail ~]# host flexstorage
+flexstorage.wesleyan.edu has address 129.133.24.81
+[root@petaltail ~]# df -h /home/dlbgroup
+Filesystem            Size  Used Avail Use% Mounted on
+flexstorage.wesleyan.edu:/share/dlbgroup
+G  588G  413G  59% /home/dlbgroup
+</code>
+Host petaltail has the following interfaces.  The file system in question is mounted on host petaltail as VLAN 1 can reach VLAN 24.
+<code>
+eth0      Link encap:Ethernet  HWaddr 00:18:8B:51:FA:42
+          inet addr:192.168.1.217  Bcast:192.168.255.255  Mask:255.255.0.0
+eth1      Link encap:Ethernet  HWaddr 00:18:8B:51:FA:44
+          inet addr:10.10.100.217  Bcast:10.10.255.255  Mask:255.255.0.0
+eth2      Link encap:Ethernet  HWaddr 00:15:17:80:8D:F2
+          inet addr:129.133.1.225  Bcast:129.133.1.255  Mask:255.255.255.0
+eth3      Link encap:Ethernet  HWaddr 00:15:17:80:8D:F3
+          inet addr:192.168.2.2  Bcast:192.168.2.255  Mask:255.255.255.0
+</code>
+But a compute node on our cluster, for example node b1, has the following interfaces, all private
+<code>
+eth0      Link encap:Ethernet  HWaddr 00:13:D3:F2:C8:EC
+          inet addr:192.168.1.7  Bcast:192.168.255.255  Mask:255.255.0.0
+eth1      Link encap:Ethernet  HWaddr 00:13:D3:F2:C8:ED
+          inet addr:10.10.100.7  Bcast:10.10.255.255  Mask:255.255.0.0
+</code>
+So in order to for the compute node b1 to reach the flexstorage server we need to use NAT rules and define a path/route.  First we start on petaltail and edit the iptables file and add a "nat filter" masquerade/post routing directives and in the "filter filter" set up a rule connecting eth1 and eth2.
+<code>
+*nat
+# fss public to 10.10
+-A POSTROUTING -o eth2 -j MASQUERADE
+COMMIT
+*filter
+# fss public via 10.10
+-A FORWARD -i eth1 -o eth2 -m state --state RELATED,ESTABLISHED -j ACCEPT
+...
+COMMIT
+</code>
+Next, on the compute nodes we need to add routing path and then mount the file system (using an IP because there is no name resolving).  These commands are stuck in /etc/rc.local for persistence.
+<code>
+# /etc/rc.local
+route add -host 129.133.24.81 gw  10.10.100.217 eth1
+mount 129.133.24.81:/share/dlbgroup /home/dlbgroup -t nfs -o soft,intr,bg
+[root@b1 ~]# df -h /home/dlbgroup
+Filesystem            Size  Used Avail Use% Mounted on
+.133.24.81:/share/dlbgroup
+G  588G  413G  59% /home/dlbgroup
+</code>
+There is ofcourse a penalty in performance doing this.
+<code>
+[root@petaltail ~]#  time dd if=/dev/zero of=/home/dlbgroup/foo bs=1024 count=1000000
+1000000+0 records in
+1000000+0 records out
+1024000000 bytes (1.0 GB) copied, 107.961 seconds, 9.5 MB/s
+real    1m47.964s
+user    0m0.322s
+sys     0m2.094s
+[root@b1 ~]# time dd if=/dev/zero of=/home/dlbgroup/foo bs=1024 count=1000000
+1000000+0 records in
+1000000+0 records out
+1024000000 bytes (1.0 GB) copied, 110.017 seconds, 9.3 MB/s
+real    1m50.027s
+user    0m0.271s
+sys     0m4.073s
+</code>

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