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--- kvm:bridge_interface [2021/04/09 10:16]
admin
+++ kvm:bridge_interface [2021/04/09 10:40] (current)
admin
@@ Line 58: / Line 58: @@
 {{ :linux:bridge_virt_01.jpg |}}
-If you have two LAN interface with two VLAN network
+==== If you have two LAN interface with two VLAN network ====
+<code bash>
+[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-br1
+DEVICE="br1"
+ONBOOT="yes"
+TYPE="Bridge"
+BOOTPROTO="none"
+IPADDR="10.5.22.51"
+NETMASK="255.255.255.0"
+GATEWAY="10.5.22.254"
+IPV6INIT="yes"
+IPV6_AUTOCONF="yes"
+DHCPV6C="no"
+STP="on"
+DELAY="0.0"
+</code>
+<code bash>
+[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-br2
+DEVICE="br2"
+ONBOOT="yes"
+TYPE="Bridge"
+BOOTPROTO="none"
+IPADDR="10.5.23.10"
+NETMASK="255.255.255.0"
+IPV6INIT="yes"
+IPV6_AUTOCONF="yes"
+DHCPV6C="no"
+STP="on"
+DELAY="0.0"
+</code>
+<code bash>
+[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
+DEVICE=eth0
+ONBOOT=yes
+BRIDGE="br1"
+</code>
+<code bash>
+[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1
+DEVICE=eth1
+ONBOOT=yes
+BRIDGE="br2"
+</code>
+<note warning>In this configuration second interface eth1 and br2 will not be accessible outside.</note>
+<note important>To use a second interface and address we need to add another routing table.To do this go to file:</note>
+<code bash>
+# vim /etc/iproute2/rt_tables
+</code>
+and add at the end “1 rt2”:
+<code winbatch>
+#
+# reserved values
+#
+     local
+     main
+     default
+       unspec
+#
+# local
+#
+#1      inr.ruhep
+rt2
+</code>
+Now we need to add routing rules and routes:
+<code bash>
+ip route add default via 10.5.23.254 dev br2 table rt2;
+ip rule add from 10.5.23.0/24 table rt2
+</code>
+You can check these changes with commands:
+<code bash>
+# ip route show table rt2
+# ip rule show
+</code>
+==== CentOS: Start custom script automatically after network startup ====
+Find the ifup-post under /etc/sysconfig/network-scripts. This scipt is called right after any network interface is brought up online. In this script, you will find the following code snippet toward the end.
+<code bash>
+if [ -x /sbin/ifup-local ]; then
+    /sbin/ifup-local ${DEVICE}
+</code>
+In the code snippet above, if ifup-local script exists in /sbin location, then script gets executed with an interface name in argument. Usually no such ecript like ifup-local exists so in order to run a startup script automatically after a network interface is up. Create an executable script called ifup-local in /sbin and put in there any command or script you wish to run.
+Here is an example:
+<code bash>
+if [[ "$1" == "eth0" ]]
+then
+  echo "this part will be executed right after eth0 is up."
+  echo "so you can put any startup command for eth0 here"
+else
+  #DO_NOTHING
+fi
+</code>
+when script is done, use command to get the script executable.
+<code bash>
+$ sudo chmod +x /sbin/ifup-local
+</code>
+<code bash>
+[root@localhost ~]# cat /sbin/ifup-local
+#!/bin/sh
+ip route add default via 10.5.23.254 dev br2 table rt2;
+ip rule add from 10.5.23.0/24 table rt2
+</code>

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