If you setup OpenVPN to be in bridge (layer2) mode instead using NAT/routing (layer3) and then restart the server to make the change effective, you probably noticed the following error message on the Status Overview page repeatedly : service failed to start due to unresolved dependencies: set([‘bridge’]) This is because there is no existing bridge… Read More »
You might encountered the following message after creating a bridge interface and try to bring it up on RHEL/CentOS Linux : ifup br0 Device br0 does not seem to be present, delaying initialization. The common error in such case is usually because you mistype the ” TYPE= ” parameter, bridge must start with a… Read More »
A bridge interface is actually a virtual interface handled by a config file on your Linux system. Creating a bridge is quite simple, just follow those steps and you’re all set! 1. Create the bridge interface configuration file : vi /etc/sysconfig/network-scripts/ifcfg-br0 Add the the following parameters : DEVICE=br0 TYPE=Bridge BOOTPROTO=static ONBOOT=yes STP=on IPADDR= NETMASK= GATEWAY=… Read More »
Juniper ScreenOS for SSG security appliance can be managed either through the Web UI or command line interface (CLI). Upgrade through the Web interface can be endless and painful. The best way to do it is through the CLI. To accomplish this task, you’ll need : – SSH or Telnet client – TFTP server Here… Read More »
If you experience issue with your subnet or receiving the following message when you try to ping an IP address, this mean you have a routing loop on your network. The same subnet might be configured on another router and the network is confused due to the different destination. You need to remove the bad… Read More »
As you might noticed on latest version of Windows, ICMP requests are blocked by default with the built-in firewall. Use this simple command to enable echo request : netsh firewall set icmpsetting 8 enable
You might notice this error trying to add a static route to your Juniper switch stack : root@ir01# set routing-options rib inet.0 static route 0.0.0.0/00 next-hop 0.0.0.0 {master:0}[edit] root@ir01# commit synchronize [edit protocols] ‘bgp’ [edit protocols] ‘ospf3’ [edit routing-options rib inet.0 static] ‘route 0.0.0.0/00’ RT: DEST: 0.0.0.0 MASK: 255.0.0.0 mask too short error: configuration check-out… Read More »
Running large and high demanding hypervisor connected to SAN storage require jumbo (large MTU) frames to enhance I/O performance to the guests virtual machines. To achieve that, you need to use the command line since vSphere console do not allow to do such thing. 1. Stop all guest virtual machine and put the hypervisor in… Read More »
You may experience this error shown on “dmesg” or system logs (/var/log/messages) : IPv6 addrconf: prefix with wrong length 126 This actually indicate a device on your network trying to broadcast IPv6 information that dosen’t match your network configuration. To get rid and disable this, simply run the following commands as root : echo 0… Read More »
If you have a full subnet to add on RHEL/CentOS Linux system, there is a short way to achieve this instead of manually create single alias interfaces. 1. Create a script at this location : vi /etc/sysconfig/network-scripts/ifcfg-eth0-range0 (ajust values as needed, according to the interface you would would have the IP subnet binded to an… Read More »