Trying to understand TELNET command

telnet 0 0 inside
the first comand will allow telnet from any host...the second command will allow telenet
from that subnet....the third command will allow telnet only from that specific host from inside my network...
Am i corrrect in my assumption?
Now what command will enable (allow)telent to PIX's outside interface(i understand it is not the  ideal setup)? lets assume  public ip for outside interface is
If i have an exchange server inside firewall and for troubleshooting i had to allow telenet
into Exchange server do i need to configure ACL and Static for the exchange ip address?

I need to learn pix like it was yesterday and will have to ask a few questions so i will keep
them simple . I appreciate your help.
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you wrote:

telnet 0 0 inside
the first command will allow telnet from any host...the second command will allow telnet
from that subnet....the third command will allow telnet only from that specific host from inside my network...
Am i correct in my assumption?

No you almost got one out of three
the format should be:
command IP mask interface
for any inside try:

telnet inside

If you wish to allow telnet to the PIX, you need to configure which hosts are allowed in. To allow a single host to telnet in via the inside interface:

    telnet inside

To allow any station on subnet /24 to telnet in via the inside interface:

    telnet inside

If you have a host on the management segment that is allowed to telnet to the PIX, you might also want:

    telnet management

If you have a device that you want to telnet into your outside interface that had the IP address, you might try:

   telnet outside

to allow someone to telnet to your exchange server you just need to open up an ACL on the public IP that is translated to your exchange server, there are many ways that you can configure this you should look at the sample config for setting up a single network from: and add telnet to the ACL
access-list 100 permit tcp any host eq telnet

also check out the pix configuration examples at cisco:


VahikAuthor Commented:
decoleur thanks for ur response. If i understand you correctly by mentioning INSIDE,DMZ
or MANAGEMENT  we are specifying the direction that TELNET is comming from and has
nothing to do with INSIDE or OUTSIDE interfaces....and if you ommit interface_name
TELNET will be allowed to PIX from anywhere inside your network..

Now the reason i asked for clarification regarding TELNET to  PIX's OUTSIDE interface  from outside was i read that it was not possible to TELNET in to your PIX's outside interface from outside??? and if so how can i TELNET in to my Exchange server if i only had one static ip assigned to me by my  ISP??? even if i were to use ACL...
i am confused but i hope i do not confuse you...
learn something new, in my example INSIDE, DMZ, and MANAGEMENT are all interface names.

I am still not quite sure, but my thinking is that if it works when you leave off the interface name you will apply the access to all interfaces with a security level of 100.

just because you are not able to telnet to the pix, does not mean that you cannot telnet through the pix.

If you only have one static IP address you must do a combination of NAT or PAT and a static translation.

look at

stay away from conduits as they are being deprecated.



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You can use telnet to the outside address of a PIX but it requires IPsec being setup to protect it - generally people will use ssh to connect to the outside interface :
ssh x.x.x.x outside
(where x.x.x.x is the public ip address of the client you wish to allow in)

If you have just one static ip and are using PAT, you ned to use port redirection to accomplish telnet to the exchange server.

To check if you are using PAT - look for the line
global (outside) 1 interface
#the number 1 may be different - it will match the inside nat pool

If you are using PAT, enter the command:
static (inside, outside) tcp interface telnet [inside ip address of exchange server] telnet netmask 0 0
#This will redirect telnet attempts to your PIX outside address (the interface) to the inside ip address of the exchange server.

clear xlate
#clears static translation table

access-list 101 permit tcp any host [PIX outside ip address] eq telnet
#Creates access list to allow telnet to the PIX

access-group 101 in interface outside
#Applies it to the outside interface

Hope this helps
Ps - as per decoleur - avoid longer supported after 6.3(4)

VahikAuthor Commented:
Thanks folks ...appreciate your help.
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