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Non Standard FTP port for server behind Cisco 1710

I am having probelms running an FTP server behind a Cisco 1710 router on a non-standard port. I have used the ip port map command but still no luck. I can connect and authenticate but as soon as I try any commands (ls, for example) it hangs. I think maybe I am missing something simple but can't seem to find it.

For example, if my internal server is on IP 192.168.0.5, the FTP server is configured for port 2021 and the external IP is 1.2.3.4 what commands would I need in the IOS to get this running.

Thanks to all in advance.

Chris L

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Re: Non Standard FTP port for server behind Cisco 1710

ip port-map command associates TCP or User Datagram Protocol (UDP) port numbers with applications or services, establishing a table of default port mapping information at the firewall. This information is used to support network environments that run services using ports that are different from the registered or well-known ports associated with a service or application.

When you issue the no form of the command, include all the parameters needed to remove the entry matching that specific set of parameters. For example, if you issued no ip port-map appl-name, then all entries for that application are removed.

The port mapping information in the PAM table is of one of three types:

?System-defined

?User-defined?Host-specific

System-Defined Port Mapping

Initially, PAM creates a set of system-defined entries in the mapping table using well-known or registered port mapping information set up during the system start-up. The Cisco IOS Firewall Context-Based Access Control (CBAC) feature requires the system-defined port mapping information to function properly.

You can delete or modify system-defined port mapping information. Use the no form of the command for deletion and the regular form of the command to remap information to another application. You can also add new port numbers to system-defined applications. However, for some system-defined applications like HTTP and Simple Mail Transfer Protocol (SMTP), in which the firewall inspects deeper into packets, their protocol (UDP or TCP) cannot be changed from that defined in the system.

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