Category Archives: Networking

FabricOS : How to remotely backup your Brocade FC switch configuration

Here is how to remotely copy your Brocade device running FabricOS to a remote TFTP server. To copy the currently running configuration : copy startup-config tftp <TFTP_Server_IP> startup-config.cfg To copy the configuration saved to the flash memory : copy run tftp <TFTP_Server_IP> switch-name.cfg To restore the remote config to your device : copy tftp start <TFTP_Server_IP>… Read More »

Networking : IPv6 subnet size reference chart

Here is a quick reference chart on subnet size for IPv6 prefixes : CIDR Number of IPs /128 1 /127 2 /126 4 /125 8 /124 16 /123 32 /122 64 /121 128 /120 256 /119 512 /118 1,024 /117 2,048 /116 4,096 /115 8,192 /114 16,384 /113 32,768 /112 65,536 /111 131,072 /110 262,144… Read More »

Juniper : Replacement fan for SSG-5-SH-W

As you probably noticed, the fan on the wireless model of Juniper SSG5 is known to be noisy over time and does not last very long (maybe a year or two if not in a dusty environment). Even though the device seem to be running fine fan less, I would not risk it on a… Read More »

Linux : How to tune up receive (TX) and transmit (RX) buffers on network interface

Modern and performance/server grade network interface have the capability of using transmit and receive buffer description ring into the main memory. They use direct memory access (DMA) to transfer packets from the main memory to carry packets independently from the CPU. The usual default buffering values for regular desktop NICs are 256 or 512 bytes. High… Read More »

ScreenOS : How to reset Juniper SSG to factory default

Here is the two procedures to reset your Juniper SSG ScreenOS device. The first method (if you have the password for your device) and serial connection to your device, you can do a software reset as followed. 1. Get your device serial number using the following command (or by reading the label on your device)… Read More »

JunOS : How to reset root password

The following procedure is about reseting root password and preserve the current configuration on your Juniper device running JunOS. 1. As soon you see “Hit [Enter] to boot immediately, or space bar for command prompt.” message, just press the space bar as indicated : FreeBSD/PowerPC U-Boot bootstrap loader, Revision 2.1 (marcelm@apg-bbuild01.juniper.net, Wed Feb 6 11:23:55… Read More »

Windows : Blocking IP from command line

Here is two commands to wither block a single or group of IPs on the Windows Firewall using the command line. Please note that you will need elevated privileges to run these commands. 1. Block a single IP (or subnet*) netsh advfirewall firewall add rule name=”IP Block” dir=in interface=any action=block remoteip=<IP_Address>/32 *You will need to… Read More »

JunOS : How to configure automated configuration backup

For sure, if you are concerned about your network you will make sure that you always have a good backup of your configuration file somewhere. Fortunately, JunOS have a nice built-in backup function through FTP or SFTP. It allow you to do an automated backup at defined time interval and even more, every time you… Read More »

Linux : OpenVPN client connection timeout after 24 hours

You probably experienced VPN session disconnection exactly 24 hours after you established the connection. Well, this is an expected behaviour since the OpenVPN Access Server implement a default 24 hours session timeout for user-locked and server-locked profiles. To workaround this limitation, you may set the timeout to a higher value using the following command : /usr/local/openvpn_as/scripts/sacli… Read More »