One of the solutions to the FTP service problem of public network address after firewall

FTP Service is built in the company because of the need of FTP public network access
Using software, free open source version of Fillzilla Server, of course this is not the main
Add user password, user access directory, change port 21 to 21212

A tricky issue arises because the company uses Cisco router public access, and the default all public ports are not turned on.
Do port mapping
IP nat inside source static TCP 192.168.1.4 21212 public address 21212 Extendale

Telnet public Address 21212
Result port is pass-through

Access after configuration with Fillzilla
Found
Access using the Window command line
C:\users\administrator>ftp
Ftp> Open Public Address 21212
Connect to the public address.
FTP Server
User (Public network address: (none)): Dtt-share
331 Password required for Dtt-share
Password:
Logged on
Ftp>dir
Port Command Successful
Opening data channel for directory listing of "/"
_

Login is successful but there is a situation where the directory cannot be accessed next

The initial consideration is that the primary passive mode of FTP is caused by:
The main passive mode is expounded in detail

The Fillzilla in the passive mode, the option has a specific port range 21200-21250, at this time encountered problems, if you do port mapping, you need to do a single port

Mapped 50 times, or a problem with the port range definition.

FTP Server public network access configuration after firewall
Firewall solution:

Cisco Router solutions:
Add configuration to the router
IP NAT Service List one-to-one FTP TCP port 21212
IP nat inside source static 192.168.1.4 public address
Access-list Permit 192.168.1.4

Refer to official information
Http://www.cisco.com/support/zh/556/6.shtml

An error occurred after discovery
Telnet public Address
Want to do a public network 23 port maintenance, found that the failure, but the other (Linux 22 and 3389) success
The problem continues to be solved ....

This article is from the "M-tier" blog, so be sure to keep this source http://mengix.blog.51cto.com/7194660/1765510

One of the solutions to the FTP service problem of public network address after firewall