How to port forward on a cisco 1720 router.

[pzs22]

Hey,

I need some help to forward a port on a 1720 (cisco) router. You have to use telnet to do it, and I have no idea how. If anyone knows the answer I would appreciate it. Can you also tell me if/how I can see what ports are being forwarded?

I have looked all over the net with no success.

Thanks

[DragonNOA1]

I'm unsure exactly but I think you have to telnet to the router IP and from there you have look around the options for where exactly to enter ports for port forwarding.

[shaticus]

I would try to console in to the router and take a look around. What version of the cisco ios is the router running? Also, take a look at your configuration (type show "running-configuration" on most versions) and post it.

[pzs22]

I tried that show command and it didn't work, here's what a show ? displayed:
show ?
backup Backup status
c1700 Show c1700 information
cca CCA information
cdapi CDAPI information
class-map Show QoS Class Map
clock Display the system clock
compress Show compression statistics
connection Show Connection
controllers Interface controller status
dialer Dialer parameters and statistics
exception exception informations
flash: display information about flash: file system
history Display the session command history
hosts IP domain-name, lookup style, nameservers, and host table
location Display the system location
modemcap Show Modem Capabilities database
policy-map Show QoS Policy Map
ppp PPP parameters and statistics
queue Show queue contents
queueing Show queueing configuration
radius Shows radius information
rmon rmon statistics
rtr Response Time Reporter (RTR)
sessions Information about Telnet connections
snmp snmp statistics
tacacs Shows tacacs+ server statistics
template Template information
terminal Display terminal configuration parameters
traffic-shape traffic rate shaping configuration
users Display information about terminal lines
version System hardware and software status

[Great_One]

after getting to a telnet prompt you need to type the command 'enable'
to get to an administrative prompt. from there you should be able to enter:

router#show run

this will show you your configuration

by default all ports are open, you need to either block all ports and only allow the ones in you need or block certain ports and allow the rest.

you need to use access lists either way.

for example

access-list 120 deny udp any any eq tftp
access-list 120 deny tcp any any eq 135
access-list 120 deny tcp any any eq 4444
access-list 120 deny icmp any any
access-list 120 permit ip any any
then you need to apply it to an interface

interface Serial0/0
ip address 192.168.1.134 255.255.255.252
ip access-group 120 in

you need to know the cisco ios to do this