Cisco DHCP Snooping

just config, it's pretty easy

!enable DHCP snooping for vlan 1

ip dhcp snooping

ip dhcp snooping vlan 1

!enable DHCP option 82

ip dhcp snooping information option

!set trust port for DHCP server

int Gi0/2

ip dhcp snooping trust

!set limit per second

int range Fa0/1 - 24

ip dhcp snooping limit rate 20

!set trust trunk port:

ip dhcp snooping trust

show settings:

show ip dhcp snooping

show ip dhcp snooping binding

Remote change power settings

you can use it if need change power settings for remote computer

get info about remote power pc settings:

PsExec.exe \\rcomputer  powercfg -query

 

disable sleep timeout:

PsExec.exe \\rcomputer  powercfg -change -standby-timeout-ac 0

 

other interesting options:

 

powercfg -change -monitor-timeout-ac 0

powercfg -change -monitor-timeout-dc 0

powercfg -change -disk-timeout-ac 0

powercfg -change -disk-timeout-dc 0

powercfg -change -standby-timeout-ac 0

powercfg -change -standby-timeout-dc 0

powercfg -change -hibernate-timeout-ac 0

powercfg -change -hibernate-timeout-dc 0

 

Remote enable Remote Desktop

This example show how you can use PsExec for enable Remote Desktop remotely

Enable RDP:

PsExec.exe \\remotepc  reg add "hklm\system\currentcontrolset\control\terminal server" /f /v fDenyTSConnections /t REG_DWORD /d 0

 

Enable RDP through firewall:

PsExec.exe \\remotepc netsh firewall set service remoteadmin enable

PsExec.exe \\remotepc netsh firewall set service remotedesktop enable

Cisco IOS clock settings

set correct time zone:

clock timezone PCTime -8

 

set summer time old ios:

clock summer-time PCTime date Mar 13 2011 2:00 Nov 6 2011 2:00

 

New IOS have other nice settings, it's need setup just one time:

clock summer-time CDT recurring

 

set ntp server:

ntp server XXX.XXX.XXX.XXX

 

set clock:

clock set 10:30:00 Jul 12 2011

 

show clock:

show clock

VPN syslog error

If vpn is up but you have errors log

%CRYPTO-4-PKT_REPLAY_ERR: decrypt: replay check failed

 

for fix it add to router

crypto ipsec security-association replay window-size 1024

Change your Windows MTU

Example how to find your correct MTU

 

1. Find your Windows MTU:

netsh interface ipv4 show subinterfaces 

 

2. Find your ISP MTU:

ping yourISPgatewayIP -f -l 1400

incrice size until you get:

Packet needs to be fragmented but DF set.

Last sucsess ping size+28 is you correct MTU

 

3. For set MTU:

netsh interface ipv4 set subinterface "Local Area Connection" mtu=1472 store=persistent

 

 

 

  

Flexible NetFlow for IOS

 

If you use vpn links standart netflow don't work with vpn links. You need use flexible netflow.

It works well with vpn links. Update your IOS if your router don't support it.   

 

Example:

 

flow exporter NETFLOW1-EXPORTER

 

 description NetFlow Analyzer

 destination 172.16.0.1

 source Loopback0

 output-features

 transport udp 9996

 export-protocol netflow-v9

!

!

flow exporter NETFLOW2-EXPORTER

 description Scrutinizer

 destination 172.16.0.2

 source Loopback0

 output-features

 transport udp 9996

 export-protocol netflow-v9

!

!

flow monitor NETFLOW1

 record netflow-original

 exporter NETFLOW2-EXPORTER

 exporter NETFLOW1-EXPORTER

 cache timeout active 1

!

!

interface Tunnel12

 ip flow monitor NETFLOW1 input

 ip flow monitor NETFLOW1 output

!

!

interface FastEthernet1

 ip flow monitor NETFLOW1 input

 ip flow monitor NETFLOW1 output

 

 

link: http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6555/ps6601/ps6965/prod_white_paper0900aecd804be1cc.html