Just quick config snippet for Debian 6.0 which I came across when setting up few Debian Linux 6.0 virtual machines for recent network LAB. By default network adapter is set to get IP address from DHCP.

/etc/network/interfaces – dynamic IP address configuration

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface auto lo iface lo inet loopback
# The primary network interface allow-hotplug
eth0 iface eth0 inet dhcp

(more…)

Recently I went through troubleshooting of Site-to-Site Layer-2 link. One of the things we did during troubleshooting of that link was checking interface statistics for interfaces which were connecting two geographical sites together.

Below quick overview how ot check and reset port statistics if required during troubleshooting process.

(more…)

Create Read Only SNMPv3 user – IOS

snmp-server group viewers v3 auth
snmp-server user snmpView viewers v3 auth md5 uHNKmuLP0lXOp8ODFkmJ
snmp-server group viewers v3 auth read viewConfig
snmp-server view viewConfig system included
snmp-server view viewConfig internet included
snmp-server view viewConfig mib-2 included
snmp-server view viewConfig cisco included
snmp-server view viewConfig ciscoConfig included
snmp-server view viewConfig ciscoImageMIB included
snmp-server view viewConfig snmpMIB included

Create Read Write SNMPv3 user – IOS

snmp-server group writers v3 auth
snmp-server user snmpWrite writers v3 auth md5 jB7HCiNBoGsk5qgfasHQ
snmp-server group writers v3 auth write writeConfig
snmp-server view writeConfig system included
snmp-server view writeConfig internet included
snmp-server view writeConfig mib-2 included
snmp-server view writeConfig cisco included
snmp-server view writeConfig ciscoConfig included
snmp-server view writeConfig ciscoImageMIB included
snmp-server view writeConfig snmpMIB included

Create Read Only SNMPv3 user – ASA

snmp-server group viewers v3 auth
snmp-server user snmpView viewers v3 auth md5 uHNKmuLP0lXOp8ODFkmJ
snmp-server host inside 0.0.0.0 version 3 snmpView

NOTE: Please keep in mind that certain ACLs might require modification in order to allow SNMP protocol access.

Usually I tend to create DHCP server on Windows Server. However, sometimes there is no server on site. Only what I have are network devices, workstations and voip phones. In those cases I used to create DHCP server on switches. As environment I operate in contains mainly Cisco devices, each location has at least one or more Cisco Catalyst switches (2960 or 3560) it is possible to provide DHCP service using IOS features. Example contains DHCP configuration for network with different VLANs for data, voice and printers.

Below is short description and set of commands demonstrating how to setup:

• DHCP scopes
• Exclusions
• Define DHCP helper on the interface
• Check status of DHCP assignments

(more…)

Configuration snippet I use to enable SSH on Cisco 2811 ISR and Catalyst 3560, but it will work on all Cisco IOS devices with appropriate IOS image which allows SSH to be enabled (IOS which has k9 in image name contains crypto compnents which allow to enable SSH).

(more…)