How to get a list of all the clients on a DHCP server.

I needed a list of client IPs and names from two MS DHCP servers. I tried several options before I found this quick command. I initially passed over netsh because it did not provide client names. Then I found out about the "1" parameter.

for /f %%j in ('"netsh dhcp server \\server01 show scope find /i "active""') do netsh dhcp server \\server01 scope %%j show clientsv5 1 >> DHCPClients.txt

for /f %%j in ('"netsh dhcp server \\server02 show scope find /i "active""') do netsh dhcp server \\server02 scope %%j show clientsv5 1 >> DHCPClients.txt

I finally started scavenging MS DNS.

I have a guest wifi network with a login portal. Every portable device that comes into the area connects but does not login. They pull a IP address and a dynamic DNS record is created. Whenever I work on the DNS server, I am overwhelmed by all the useless records.

Here are a few stats on my zone.

1459 records
234 iPhones
32 iPads
36 iPods
140 droids

So I looked into scavenging and enabled it one of the DNS servers. I found 2501 in the event log.

The DNS server has completed a scavenging cycle:
Visited Zones     = 14,
Visited Nodes     = 2536,
Scavenged Nodes   = 1923,
Scavenged Records = 3556.
This cycle took 5 seconds.
The next scavenging cycle is scheduled to run in 168 hours. 

Now my zone now has 294 records and no mobile devices at the moment.

How to monitor the number of network connections on a server.

I am troubleshooting a server problem and want to monitor the number of network connections. You need wc (wordcount) for Windows. The choice command gives me a three second delay.

Here is my script.

echo off
:loop
netstat -an | wc
choice /n /d n /t 3 >nul
goto loop

Here is the output. The first column should be the number of network connections on my server.

    234     903   15101
    296    1151   19199
    391    1531   25465
    494    1943   32271
    469    1843   30617
    391    1531   25465
    391    1531   25465
    545    2147   35629
    545    2147   35629

Quick Cisco 3845 IOS update

I have used several methods to update IOS but the easiest for me is old fashioned FTP.

Copy the image from an FTP server to the router.

copy ftp://user:pass@10.1.2.3 flash

Tell the router to boot form the new software image.

boot system flash c3845-advsecurityk9-mz.124-25a.bin

http://proisk.com/?q=c3845-sp (interesting site)

Simple script to clone a Vmware server.

I needed to clone a couple of virtual machines so I installed PowerCLI and created this small script. I can schedule this and have daily backups. I know cloning may not be the best form of backup but this is what I need today.

c:\>type clone.ps1
connect-viserver 10.1.2.3
remove-vm -deletefromdisk "vm1 - backup"
new-vm -name "vm1 - backup" -datastore ds1 -vm "vm1" -vmhost v01.example.com
disconnect-viserver
c:\>

Enable remote desktop from the command line.

For some reason the regedit gui would not connect to the remote Windows 7 pc. I used my favorite tool Psexec from the command line and this worked!

reg add "hklm\system\currentcontrolset\control\terminal server" /v fDenyTSConnections /t REG_DWORD /d 0x0

This is how to verify the change.

reg query "hklm\system\currentcontrolset\control\terminal server" 

   fDenyTSConnections    REG_DWORD    0x0

Quick speed test between two servers with Iperf.

Iperf for Windows - free and portable!
http://linhost.info/2010/02/iperf-on-windows/

Server A:
iperf -s

Server B:
iperf -c x.x.x.x -P 5

[SUM]  0.0-10.0 sec  1.08 GBytes   927 Mbits/sec
(Not bad for 1gb network.)

The default test is 10 seconds, add "-t 60" for a longer test.