3Com 3CRWER300-73 Router Manual PDF (Setup & Configuration Guide)

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■

Total incomplete TCP/UDP sessions HIGH - Defines the rate of new

unestablished sessions that will cause the software to start deleting

half-open sessions.

■

Total incomplete TCP/UDP sessions LOW - Defines the rate of new

unestablished sessions that will cause the software to stop deleting

half-open sessions.

■

Incomplete TCP/UDP sessions (per min) HIGH - Maximum number of

allowed incomplete TCP/UDP sessions per minute.

■

Incomplete TCP/UDP sessions (per min) LOW - Minimum number of

allowed incomplete TCP/UDP sessions per minute.

■

Maximum incomplete TCP/UDP sessions number from same host -

Maximum number of incomplete TCP/UDP sessions from the same

host.

■

Incomplete TCP/UDP sessions detect sensitive time period - Length of

time before an incomplete TCP/UDP session is detected as incomplete.

■

Maximum half-open fragmentation packet number from same host -

Maximum number of half-open fragmentation packets from the same

host.

■

Half-open fragmentation detect sensitive time period - Length of time

before a half-open fragmentation session is detected as half-open.

■

Flooding cracker block time - Length of time from detecting a flood

attack to blocking the attack.

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Firewall

85

Special Applications

Special Applications (port triggering) let you choose specific ports to be

open for specific applications to work properly with the Network Address

Translation (NAT) feature of the Router.

Figure 66

Special Applications Screen

A list of popular applications has been included to choose from. Select

the application from the

Popular Applications

drop-down menu. Then

select the row that you want to copy the settings to from the

Copy To

drop-down menu, and click

Copy To

. The settings will be transferred to

the row that you specified. Click

Apply

to save the setting for that

application.

If your application is not listed, you will need to check with the

application vendor to determine which ports need to be configured. You

can manually enter the port information into the Router. To manually

enter the port information:

1

Specify the trigger port (the one used by the application when it is

initialized) in the

Trigger Port

column, and specify whether the trigger is

TCP or UDP.

2

Specify the Public Ports used by the application, that will need to be

opened up in the firewall for the application to work properly. Also

specify whether these ports are TCP or UDP. Note that the range of the

trigger port is from 1 to 65535. You can enter the port number as one

single port, or in range, use comma to separate different entries.

3

Check the

Enabled

checkbox, then click

Apply.

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Virtual Servers

The Virtual servers feature allows you to route external (Internet) calls for

services such as a web server (port 80), FTP server (Port 21), or other

applications through your Router to your internal network. Since your

internal computers are protected by a firewall, machines from the

Internet cannot get to them because they cannot be 'seen'.

If you need to configure the Virtual Server function for a specific

application, you will need to contact the application vendor to find out

which port settings you need.

The maximum number of virtual servers that can be configured is 20.

Figure 67

Virtual Servers Screen

A list of popular servers has been included to choose from. Select the

server from the

Popular servers

drop-down menu. Then click

Add

, your

selection will be added to the table.

If the server that you want to use is not listed in the drop-down menu,

you can manually add the virtual server to the table. To manually

configure your virtual servers:

1

Enter the IP address, and the description in the spaces provided for the

internal machine.

2

Select the protocol type (TCP, UDP, or both TCP and UDP) from the

drop-down menu.

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Firewall

87

3

Specify the public port that will be seen by clients on the Internet, and the

LAN port which the traffic will be routed to.

4

You can enable or disable each Virtual Server entry by checking or

unchecking the appropriate

Enabled

checkbox.

5

Click

Apply

to save the changes for each Virtual Server entry.

DMZ

If you have a client PC that cannot run an Internet application properly

from behind the firewall, you can open the client up to unrestricted

two-way Internet access. This may be necessary if the NAT feature is

causing problems with an application such as a game or video

conferencing application.

Figure 68

DMZ Screen

Use this feature on a temporary basis. The computer in the DMZ is not

protected from hacker attacks.

Check the

Enable DMZ

box, the IP Address of Virtual DMZ Host will

appear.

1

Enter the last digits of the LAN IP address in the

Client PC IP Address

field.

Enter the IP address (if known) that will be accessing the DMZ PC into the

Public IP Address

field, so that only the computer on the Internet at this

address can access the DMZ PC without firewall protection. If the IP

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address is not known, or if more than one PC on the Internet will need to

access the DMZ PC, then set the

Public IP Address

to

0.0.0.0

.

In the default setting (line 1), Public IP address is set to 0.0.0.0 and it is

automatically transformed by default WAN IP. We only allow one DMZ

server to be accessed by public IPs (Many to 1 NAT). If you have more

than one DMZ server, you have to set a second WAN IP in line 2 and

define which IP address of DMZ server you would like to set in the Client

PC IP address. For this Router, only 1 to 1 NAT function is allowed.

2

Click

Apply

.

PC Privileges

The Router can be configured to restrict access to the Internet, email or

other network services at specific days and times. Restriction can be set

for a single computer, a range of computers, or multiple computers.

You can define the traffic type permitted or not-permitted to the Internet.

Note that this function requires timescheduling to be applied to access

control, you will need to create schedule rules first and then use PC

Privileges.

Figure 69

PC Privileges Screen

1

Select one option from filtering function:

■

All PCs have access to the Internet: selecting this mode means that all

clients have full access to Internet.

■

PCs access authorised services only:

2

Click

Add PC

(refer to

Figure 70

).

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