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Practical - Cisco

Install user language into Cisco IP Phone

Very important thing is, that your IP phone has to have letter "G" in its name. For example "Cisco Unified IP Phone 7970G" or "7960G". Letter "G" means, that phone is "global", and also support other laguages than english.

Do not confuse it with "GE". This means "giabit ethernet". If phone support both, there is "G-GE" on the phone.


Uncompressing Cisco .cop.sgn file

Cisco releases some files (firmware, language files, ...) as .cop.sgn files. And sometimes, you need to uncompress it and reach files in this archive. "sgn" means, it is signed. Actually, there is only authentication header, which can be removed by editor. For Linux, we can use Bless hex editor. Open file in editor, and find pattern '1F 8B 08'.

Your file should start with this pattern.

How to clear an ASA startup configuration

If we have access to config mode we may type

config t
configure factory-default


Problem with unpacking ASA image with unpack 0.1-win tool

When I was trying to unpack ASA 8 image using GNS3 utility unpack0.1-win on my windows 7, I always received following error:

How and where to find and download the Cisco SDM manager

The Security Device Manager, or SDM is possible to find on www.cisco.com on the following web link


The Cisco Connection online (CCO) user guest account is needed, which we may create for free.

DHCP configuration using SDM

The flash animation explains how to configure DHCP server on a cisco router using the SDM. Where to find and how to install the SDM is described in this article.


Cisco-Linksys SRW 248G4 - system firmware recovery

In this article I will describe how to proceed if your firmware upgrade on SRW 248G4 switch failed and the switch then stop working.

I have found only one solution how to recover from this disaster and it is sending a new firmware over PC serial (COM) port using xmodem protocol. A new firmware can be send to the failed switch with the help of Startup menu of the switch. The Startup menu can be entered when the switch is booting.

So, steps are following:

Zmena preddefinovaného telnet klienta v dynagene za putty

Dynagen obsahuje cmd príkaz, ktorý umožňujú pripojenie na konzolu virtuálnych routrov priamo z jeho príikazového riadku, je to príkaz telnet. Tento príkaz v dynagene spustí preddefinovaného klienta a pripojí ho na lokálny, v net konfigu zadefinovaný port. Vo windows to znamená že sa spustí windows telnet klient. Toto predefinované nastavenie môžeme zmeniť tak, aby bol spúšťaný iný klient, napr. preferované Putty.

IOS recovery using other Cisco router as the TFTP server and tftpdnld

The students in our labs oftenly delete not just startup configuration but the whole IOS of a router. Then the IOS of the router have to be recovered. There is one way using the COM port, but it takes time (tens of minutes). The second way is to use an another router with the same IOS as the TFTP server.




R1 will serve as the tftp server, R2 we have to recover. Routers are connected back-to-back using the cross cable.

Catalyst 2960 - password recovery

Recovering from a Lost or Forgotten Password


The default configuration for the switch allows an end user with physical access to the switch to recover from a lost password by interrupting the boot process during power-on and by entering a new password. These recovery procedures require that you have physical access to the switch.



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