These commands create a global address of The conduit command statement permits any outside users to access the mail server at the SMTP port You will need to inform your DNS administrator to create an MX record for the global address such as We recommend that you not use the any keyword instead of specifying an IP address of a host that can access the static mapping in the conduit command statement.
Using any lets any outside host access the static. In cases, such as for a server available for public access, using any is the only choice. However, if you can limit the number of users who have access to a server, you reduce the chance of intrusion. This is very important when there are multiple interfaces. If you set up a conduit command for the dmz2 interface to access the dmz1 interface, you would not want outside users to be able to access the conduit command.
PIX Firewall handles this for you. It automatically determines which interfaces are mapped together with the static command statement. Two conduit command statements are required for establishing access to the following services: discard, dns, echo, ident, pptp, rpc, sunrpc, syslog, tacacs-ds, talk, and time.
The two conduit command statements for the PPTP transport protocol, which is a subset of the GRE protocol, are as shown in this example:. In this example, PPTP is being used to handle access to host Outside users access the dmz2 host using global address The first conduit command statement opens access for the PPTP protocol and gives access to any outside users.
The second conduit permits access to GRE. Step 4 Add the remaining static and conduit command statements:. These command statements create a global address on each interface to map to the inside mail server and then create a conduit so that users on each interface can access the mail server via the SMTP port Step 5 Let users know how to access the server.
Users on the inside access the server at Step 1 Add command statements to let users on the various interfaces access the web server on dmz2.
The static and conduit command statements work the same way as described previously for the mail server, creating a global address through which users on the interface can access the web server. The global command adds a new dimension to server access.
Because the inside interface is at a higher security level than the dmz2 interface, instead of using static and conduit command statements to permit access, you use nat and global command statements. The nat command statement lets inside users start connections on any interface of a lower security level; therefore, they can access the dmz2 interface.
The global command lets the inside users translate their connections to access the address of the web server on the dmz2 interface. Step 2 Let users know what IP address to use to access the server. For users on the inside interface, they would access the web server at address Users on dmz1 would access it at Specify a static route for each network connected to any router.
Refer to the section " Step 7 - Create a Default Route " for information on default routes, and to the section " Step 3 - Configure Network Routing " for information on configuring routers and hosts for default routes. Step 1 Sketch out a diagram of your network as shown in. Step 2 When you have three or more interfaces as shown in the diagram, only one default route is permitted:.
This command statement sends all packets destined for the default route, IP address 0. The "1" at the end of the command statement indicates that the router is the router closest to the PIX Firewall; that is, one hop away.
In addition, you must add static routes for the networks that connect to the inside router as follows:. These static route command statements can be read as "for packets intended for either network The PIX Firewall is not a router and cannot make these decisions.
The "1" at the end of the command statement specifies how many hops routers the router is from the PIX Firewall. Because it is the first router, you use 1. Step 3 Add the static routes for the dmz4 interface:. These command statements direct packets intended to the The syslog message facility in the PIX Firewall is a useful means to view troubleshooting messages and to watch for network events such as attacks and service denials.
Step 1 Use the enable command followed by the configure terminal command to get to configuration mode. This command opens syslog up for all possible messages. The debugging setting is very useful for troubleshooting, but on a PIX Firewall in production, will generate too many messages to make troubleshooting viable. If you are testing a production mode PIX Firewall, substitute the errors keyword for the debugging keyword.
This will reduce the messages to only those generated by logging levels 0, 1, 2, and 3. If your security policy permits pings, ensure that the ICMP conduit is in your configuration by using the show conduit command and checking for this command statement:.
Step 4 View the syslog messages with the show logging command. New messages append to the end of the display. Step 5 To clear the messages in the buffer, use the clear logging command. Step 6 When done, set the logging buffered command back to a minimal setting such as:. For example, to an internal interface:. Enter the Telnet password, which is cisco by default. This password is set with the passwd command.
Step 3 Use the enable command followed by the configure terminal command to get to configuration mode. Step 4 Start message logging with the logging monitor command.
Step 5 Display messages directly to the Telnet session by entering the terminal monitor command. Step 6 Use a host on an internal network to ping a host on the outside or start a web browser. These actions should create syslog events. The syslog messages then appear in the Telnet session window. Step 7 To disable viewing syslog messages with Telnet, use these commands:. The information in the remainder of this section describes additional information on the logging command and how to configure PIX Firewall to send messages to a syslog server.
In the event that all syslog servers are offline, PIX Firewall stores up to messages in its memory. Subsequent messages that arrive overwrite the buffer starting from the first line. Unless you need the certainty that every syslog message sent must be stored on the PFSS, and you can afford the possible network downtime to free the Windows NT disk space, only use UDP logging.
Step 1 Designate a host to receive the messages with the logging host command. For normal syslog operations to any syslog server, use the default message protocol, UDP, as shown in the following example:. Replace interface with the interface on which the server exists, address with the IP address of the host, and port with the TCP port if different than the default value of You can see if PIX Firewall traffic has been disabled due to a PFSS disk-full condition with the show logging command and look for the "disabled" keyword in the display.
A subsequent command statement overrides the previous one. Use the write terminal command to view the logging host command statement in the configuration. Step 2 Set the logging level with the logging trap command; for example:.
Cisco recommends that you use the debugging level during initial setup and during testing. Thereafter, set the level from debugging to errors for production use. Step 3 If needed, set the logging facility command to a value other than its default of Step 4 Start sending messages with the logging on command.
To disable sending messages, use the no logging on command. Step 5 If you want to send time stamped messages to the PFSS, use the clock set command to set the PIX Firewall system clock and the logging timestamp command to enable time stamping.
In this example, the clock is set to the current time of pm on April 1, , and time stamping is enabled. To disable time-stamp logging, use the no logging timestamp command.
You can access version 5. You can re-enable all previously blocked messages with the following command:. Beginning operation. All PFSS parameter values can be viewed by examining the pfss.
The PFSS starts immediately after installation. You can use the Services control panel to enter new parameters, pause the service and then resume the service, or to stop and start the service. Choose one or more parameters from the following:. This is an integer value in the range of 1 to The default is If you specify another port, it must be in the range of to If you specify Another port, it must be in the range of to The default is 5 seconds, the range is any number greater than zero.
The default is 3 seconds, the range is any number greater than zero. Step 1 Open the Services control panel. Step 3 In the Startup Parameters edit box, type -d 35 -f Step 4 Click Start. Pressing the Enter key closes the Services control panel and does not change the parameters. PFSS stores syslog messages in one of seven files: monday. If a week has already passed since the last log file was created, it will rename the old log file to weekday.
Note PFSS truncates syslog messages longer than characters in length. You then need to back up all the log files to another disk or across the network. While PFSS is receiving messages, the log files must reside on the local disk. Step 1 Back up the files on the Windows NT system. If the syslog server has disabled the connection, the display contains the "disable" keyword.
Step 4 Restart logging with the logging host command; for example:. Step 5 Check that the server is now enabled with the show logging command. The "disabled" keyword should no longer be visible.
The logging facility and logging level commands configure the facility and level of syslog messages. Because network devices share the eight facilities, the logging facility command lets you set the facility marked on all messages. Messages are sent to the syslog host over UDP. The logging on command starts sending messages. Use the logging host command to specify which systems receive the messages. The PIX Firewall generates syslog messages for system events, such as security alerts and resource depletion.
Syslog messages may be used to create email alerts and log files, or displayed on the console of a designated host using UNIX syslog conventions. The logging facility and logging trap commands let you specify the syslog facility and level for how messages are sent to the syslog host. Hosts file the messages based on the facility number in the message.
The level specifies the types of messages sent to the syslog host. Setting the level to 3, the default value, for example, allows messages with levels 0, 1, 2, and 3 to display. The default is 3. This section describes how to configure a UNIX host to receive syslog messages. This configuration directs the PIX Firewall syslog message to the specified file. Alternatively, if you want the message sent to the logging host console or emailed to a system administrator, refer to the UNIX syslog.
Blanks are not acceptable. PIX Firewall provides the outbound and apply commands that you can use to limit internal users access to services on external interfaces.
Use these commands to limit access for users who are on a higher security level interface from accessing a lower security level interface; for example, from the inside to the outside, from the inside to a perimeter interface, or between perimeter interfaces. These commands follow the direction of the nat command—also from a higher security level interface to a lower security level interface.
The outbound and apply commands' use is very interwoven. Depending on how you set the apply command, you use the outbound command to specify the details.
The outbound command specifies whether you are permitting or denying access, the affected IP addresses, and the port number or numbers. To coordinate the outbound and apply command statements, there is an identification number on both commands called the "list ID. This number is independent of the nat and global commands identification numbers—you can use the same number or another. Cisco recommends coding list IDs with gaps in the range to permit future additions, such as 10, 20, 30, or , , Just be sure to use the same list ID on the apply command statement as on the outbound command for the same group.
In addition, the order in which you specify the outbound commands determines how PIX Firewall evaluates them. The outbound command statements are ordered first by denies, then permits, and then by the list ID. There are a few caveats with the outbound command. Step 1 Use the show nameif command to view the security levels of each interface. Step 2 Use a nat command statement to let the users on the higher security level interface start connections on lower security level interfaces.
For example, use nat inside 1 0 0 to let inside users start connections, use nat dmz1 1 0 0 for dmz1 users, or nat dmz2 1 0 0 to let dmz2 users start connections.
Step 1 Create a blanket deny statement to limit higher security level users from accessing whatever service you are limiting. For example, to limit users on the Step 2 If required, permit access to those users who require access to this service; for example, to researchers who need to use chat in their work:. Step 3 Then add the apply command statement to determine how you want to use the outbound list.
Step 1 In this example, you want to keep dmz1 users from accessing a specific web site at Step 2 Add the apply command statement:. These messages report the results of monitoring the link status of the specified interface.
Action If the link status is down, verify that the network connected to the specified interface is operating correctly.
This message is logged when the PIX Firewall tests a specified network interface. This testing is performed only if the PIX Firewall fails to receive a message from the Standby unit on that interface after the expected interval. This message reports the result either "Passed" or "Failed" of a previous interface test. Action None required if the result is "Passed. Explanation Block memory has been depleted.
This is a transient message and the PIX Firewall should recover. Action Use the show blocks command to monitor the current block memory. Explanation The failover cable is not permitting communication between the Primary and Secondary units. Action Ensure that the cable is properly connected. Explanation When a failover occurs, the active PIX Firewall detects a partial configuration in memory. Normally, this is caused by an interruption in the replication service.
If failovers happen continuously, check the failover configuration and make sure both PIX Firewalls can communicate with each other. Explanation This is a connection-related message. This message occurs when an attempt to connect to an inside address is denied by your security policy.
This message is logged if the specified connection fails because of an outbound deny command statement. Action Use the show outbound command to check outbound lists. This message is logged if an inbound UDP packet is denied by your security policy. The flag variable is either Response or Query. Action If the inside port number is 53, it is likely that the inside host is set up as a caching nameserver.
Add an access-list command statement to permit traffic on UDP port If the outside port number is 53, the most likely cause is that a DNS server was too slow to respond, and the query was answered by another server. This message is logged if an inbound connection is denied by your security policy. This message occurs when a packet is sent to the same interface that it arrived on.
This usually indicates that a security breach is occurring. When the PIX Firewall receives a packet, it tries to establish a translation slot based on the security policy you set with the global and conduit commands, and your routing policy set with the route command.
Failing both policies, PIX Firewall allows the packet to flow from the higher priority network to a lower priority network, if it is consistent with the security policy. If a packet comes from a lower priority network and the security policy does not allow it, PIX Firewall routes the packet back to the same interface.
To provide access from an interface with a higher security to a lower security, use the nat and global commands. For example, use the nat command to let inside users access outside servers, to let inside users access perimeter servers, and to let perimeter users access outside servers.
To provide access from an interface with a lower security to higher security, use the static and conduit commands. For example, use the static and conduit commands to let outside users access inside servers, outside users access perimeter servers, or perimeter servers access inside servers. Action Fix your configuration to reflect your security policy for handling these attack events.
A IP packet was seen with IP options. Because IP options are considered a security risk, the packet was discarded. Action A security breach was probably attempted. Check the local site for loose source or strict source routing. It is discarded because the inbound packet can not specify which PAT host should receive the packet. By default, all ICMP packets are denied access unless specifically permitted using the conduit permit icmp command.
If this is the case, trace the packets to the source and determine the reason these packets were sent. Explanation This message is logged when the PIX Firewall discards a packet with an invalid source address. Invalid sources addresses are those addresses belonging to the following:. Furthermore, if sysopt connection enforcesubnet is enabled, PIX Firewall discards packets with a source address belonging to the destination subnet from traversing the PIX Firewall and logs this message.
To further enhance spoof packet detection, use the conduit command to configure the PIX Firewall to discard packets with source addresses belonging to the internal network. Action Determine if an external user is trying to compromise the protected network. Check for misconfigured clients. Explanation This message appears when PIX Firewall receives a packet with the IP source address equal to the IP destination and the destination port equal to the source port.
This indicates a spoofed packet designed to attack systems. This attack is referred to as a Land Attack. Action If this message persists, an attack may be in progress. The packet does not provide enough information to determine where the attack originates. Explanation The PIX Firewall discarded an IP packet with a teardrop signature containing either a small offset or fragment overlapping.
Action Contact the remote peer administrator or escalate this issue according to your security policy. Explanation Someone is attempting to spoof an IP address on an inbound connection. Unicast Reverse Path Forwarding, also known as reverse route lookup, detected a packet that does not have a source address represented by a route and assumes it to be part of an attack on your PIX Firewall. Action This message appears when you have enabled Unicast Reverse Path Forwarding with the ip verify reverse-path command.
This feature works on packets input to an interface; if it is configured on the outside, then PIX Firewall checks packets arriving from the outside. If an entry is not found and a route is not defined, then this syslog message appears and the connection is dropped. If there is a route, PIX Firewall checks which interface it corresponds to.
If the packet arrived on another interface, then it is a spoof or there is an asymmetric routing environment. PIX Firewall does not support asymmetric routing where there is more than one path to a destination. An attack is in progress. With this feature enabled, no user action is required.
PIX Firewall repels the attack. Explanation This message only happens if a connection exists and a packet matching the connection arrives on a different interface than what interfaces the connection began on.
For example, if a user starts a connection on the inside interface, but the PIX Firewall detects the same connection arriving on a perimeter interface, then either the PIX Firewall has more than one path to a destination, which is known as asymmetric routing and is not supported on the PIX Firewall, or an attacker is attempting to append packets from one connection to another as a way to break into the PIX Firewall.
In either case, PIX Firewall displays this message and drops the connection. Action This message appears when ip verify reverse-path is not configured. Ensure routing is not asymmetric. Explanation This is an alert log message. This could be due to misconfiguration on the router or the PIX Firewall or it could be a unsuccessful attempt to attack the PIX Firewall unit's routing table.
Action This may be an attack and should be monitored. If you are not familiar with the source IP address listed in this message, change your RIP authentication keys between trusted entities.
An attacker may be trying to deduce the existing keys. Explanation This is an alert message. This could be a router bug, a packet with non-RFC values inside, or malformed entries. This should not happen and may be an attempt to exploit the PIX Firewall unit's routing table. The packet has passed authentication, if enabled, and bad data is in the packet. The situation should be monitored and the keys should be changed if there are any doubts as to the originator of the packets.
This message is logged if the PIX Firewall replaces an invalid character in an email address with a space. Explanation This is an AAA message. This message is logged if an authentication request fails because the specified authentication server cannot be contacted by the PIX Firewall.
Action Check to be sure the authentication daemon is running on the specified authentication server. This message is logged if no authentication server can be found. Make sure the daemon s are running. This message is logged when the specified authentication request succeeds.
This message is logged if the specified authentication request fails, possibly because of a misstyped password. This message is logged when the specified authorization request succeeds.
This message is logged if a user is not authorized to access the specified address, possibly because of a misstyped password. This message is logged if an authentication request cannot be processed because the server has too many requests pending.
Action Check to see if the authentication server is too slow to respond to authentication requests. Enable floodguard with the floodguard enable command.
Explanation An authentication session started between the host and the PIX Firewall and has not yet completed. Explanation The authentication cache has timed out. Users will need to reauthenticate on their next connection. You can change the duration of this timer with the timeout uauth command. Explanation The user must be authenticated before using the service. Explanation A request to authenticate did not have a corresponding request for authorization.
Action Ensure that both the aaa authentication and aaa authorization command statements are provided in the configuration. Explanation The access list check failed; either it matched a deny, or it matched nothing, such as an implicit deny. Explanation This message indicates a route lookup failure. This is the default firewall port allocation for Windows Media Services in order to deliver a unicast stream:.
In order to make sure that your content is available to all client versions that connect to your server, open all ports described in the table for all of the connection protocols that can be used within protocol rollover. In this section, you are presented with the information to configure the features described in this document.
Note: Use the Command Lookup Tool registered customers only to obtain more information on the commands used in this section. Note: The IP addressing schemes used in this configuration are not legally routable on the Internet. They are RFC addresses that have been used in a lab environment. Use the OIT to view an analysis of show command output. Packets can be fragmented, and the security appliance cannot perform NAT on fragmented packets. Contents Introduction.
If you do not see this command in your configuration, add it now. A default route command is crucial to get other commands to work correctly. If you are testing the network before putting it into production, get a router and add it to the test network so that the PIX Firewall has a default route. Also, it is best to keep all the nat statements and globals in the same NAT ID even if the global statements refer to different interfaces, for example:. The nat statements let users on the inside, dmz1, and dmz2 interfaces start outside connections.
The first global statement creates a PAT address on the outside interface at the end of the range of globals. PIX Firewall reads through the global IP addresses starting from the highest and going to the smallest. The second global statement creates a pool of IP addresses in the range of The third global statement creates a pool of IP addresses on the dmz1 interface.
Step 4 Use the show global command to make sure that a range of global addresses starts from a low number and goes to a high number. In addition, it is good to leave a few addresses before the range for static statements, hosts, or additional routers.
In other words, instead of starting the global pool at an address such as This expands your pool of addresses, if needed. Remember to give the PAT an address lower than the pool of global addresses. Step 6 If you are using subnetting, examine Appendix E , " " for more information on subnetting. Use the show global command to make sure that all addresses in the global pool are in the same subnet.
For example, if you have a Also make sure that the global pool does not contain subnetted network addresses or broadcast addresses as explained in Appendix E. For example, with the Each interface needs its own subnet. For example, if the outside interface has registered addresses For example, if you are using a.
Step 7 Use the show nat command If you need to restrict IP addresses in nat statements, do not overlap the groups. An example is:. If you want only users on the Step 8 Use the show ip address command to check all IP addresses to be sure you have the correct addresses values for the devices.
Make sure all inside interface or perimeter interface hosts and routers have their default routes set to the respective PIX Firewall interface IP address. Refer to section "Step 3 - Configure Network Routing" for more information. For the steps that follow, you will need access to the PIX Firewall console and to at least one host on both the internal and external networks. Use the steps that follow to determine whether or not the firewall is functioning correctly in the network:.
Step 1 Sketch a diagram of your network—With a sketch, it is much easier to methodically test the network with the PIX Firewall to be sure if everything works as expected:. Step 1 Start debugging commands—Enter configuration mode and start the debug icmp trace command to monitor ping results through the PIX Firewall. In addition, start syslog logging with the logging buffered debugging command to check for denied connections or ping results.
The debug messages display directly on the console session. You can view syslog messages with the show logging command. If you are using version 4. If the debug command finds a Telnet session, it automatically sends the debug output to the Telnet session instead of the console. This will cause the serial console session to seem as though no output is appearing when it is really going to the Telnet session.
Then go to a host or router on each interface and ping the PIX Firewall's interface. For the example, you would use these commands from the PIX Firewall:. Then ping the PIX Firewall interfaces from the hosts or routers with commands such as:. If the pings from the hosts or routers to the PIX Firewall interfaces are not successful, check the debug messages which should have displayed on the console.
Successful ping debug messages appear as in this example:. Both the request and reply statements should appear to show that the PIX Firewall and responded. For example,. Add this command if it is not present. If so, set the host's default gateway to the router and set the router's default route to the PIX Firewall. Setting default routes in routers and hosts is explained in the section " Step 3 - Configure Network Routing.
If so, make sure the default route on the router points to the PIX Firewall interface. If there is a hub between the host and the PIX Firewall, make sure that the hub does not have a routing module. If there is a routing module, configure its default route to point to the PIX Firewall.
If the display contains "line protocol is up," then the cable type used is correct and connected to the firewall. If the display states that each interface "is up," then the interface is ready for use. If both of these are true, check "packets input" and "packets output. If there is not a host on the interface, ping the router.
If the ping is not successful, check the debug messages on the PIX Firewall console to be sure both inbound and outbound pings were received. If you see the Inbound message without the Outbound, then the host or router is not responding. Check that the nat and global statements are correct and that the host or router is on the same subnet as the outside interface.
Step 3 Once you can ping successfully across interfaces of higher security levels to lower security levels, such as inside to outside, inside to dmz, or dmz2 to dmz1, add static and conduit statements as described in the section " Step 13 - Add Server Access " so that you can ping from the lower security level interfaces to the higher security level interfaces. The serial console lets a single user configure the PIX Firewall, but many times this is not convenient for a site with more than one administrator.
PIX Firewall lets you access the serial console via Telnet from hosts on the inside interface. For example, to let host Step 2 If required, set the duration for how long a Telnet session can be idle before PIX Firewall disconnects the session.
The default duration, 5 minutes, is too short in most cases and should be increased until all pre-production testing and troubleshooting has been completed. Set a longer idle time duration as shown in the following example:. Step 3 Save the commands in the configuration using the write memory command.
For example, if the inside interface IP address is Enter cisco and press the Enter key. You are then logged into the PIX Firewall. You can enter any command on the Telnet console that you can set from the serial console, but if you reboot the PIX Firewall, you will need to log back into the PIX Firewall after it restarts. However, you can access the last entered commands by pressing Ctrl-P. Step 3 Once you have Telnet access available, you may want to view ping information while debugging.
Starting with version 4. Version 4. In versions prior to 4. Step 4 In addition, you can use the Telnet console session to view syslog message:. The "7" will display all syslog messages. If you are using the PIX Firewall in production mode, you may wish to use the logging buffered 7 command to store messages in a buffer that you can view with the show logging command, and clear the buffer for easier viewing with the clear logging command.
To stop buffering messages, use the no logging buffered command. You can also lower the number from 7 to a lesser value, such as 3, to limit the number of messages that appear. To disable message displays, use the terminal no monitor command. The location of the Trace Channel depends on whether you have a simultaneous Telnet console session running at the same time as the console session, or if you are using only the PIX Firewall serial console:.
If that session closes, the serial console session become the Trace Channel. The next Telnet console session that accesses the console will then become the Trace Channel. However, you can enable or disable this command from either the serial console or a Telnet console sessions. Note The downside of the Trace Channel feature is that if one administrator is using the serial console and another administrator starts a Telnet console session, the serial console debug icmp trace and debug sqlnet output will suddenly stop without warning.
In addition, the administrator on the Telnet console session will suddenly be viewing debug output, which may be unexpected.
If you are using the serial console and debug output is not appearing, use the who command to see if a Telnet console session is running. By default, the PIX Firewall prevents all outside connections from accessing "inside" hosts or servers. Any server on a network that has a higher security level than the current interface requires a static and conduit statement. Note If you are using nat 0, refer to the static command page for information about how to handle server access in this environment.
For example to let outside users access a dmz1 web server, you could have static and conduit statements as follows:. In this example, the static command maps access to the dmz1 host The conduit command lets any users on the outside access IP address In this example, the higher security level interface is dmz1 and the lower is the outside interface. On the outside interface, through the use of DNS, a company can map The idea is to present an IP address to users on one interface that gives them access to a host on another.
You use the static command to let users on a lower security level interface access a server on a higher security level interface. You use the nat command to let users on a higher security level interface access a lower security level interface.
Step 1 View the security levels with the show nameif command. Step 2 Sketch out a diagram of your network and label each interface with its security level and the IP addresses of the hosts you want to provide access to. From this scenario, you will need static statements to let outside users access the dmz2 web server and for dmz1 users to access dmz2.
You will need a nat statement to let inside users access the dmz2 web server. For the mail server, you will need static statements for access from the outside, dmz1, and dmz2. Step 3 Provide access from the outside to the inside mail server with these commands:.
These commands create a global address of The conduit statement permits any outside users to access the mail server at the SMTP port You will need to inform your DNS administrator to create an MX record for the global address such as The "any" in the conduit statement means that any host on the outside interface can access the conduit because the static associates an inside server to an outside address.
PIX Firewall makes this distinction to protect access to the conduits. This is very important when there are multiple interfaces. If you set up a conduit for the dmz2 interface to access the dmz1 interface, you would not want outside users to be able to access the conduit.
PIX Firewall handles this for you. It automatically determines which interfaces are mapped together with the static statement. Two conduit statements are required for establishing access to the following services: discard, dns, echo, ident, pptp, rpc, sunrpc, syslog, tacacs-ds, talk, and time. In this example, PPTP is being used to handle access to host Outside users access the dmz2 host using global address The first conduit statement opens access for the PPTP protocol and gives access to any outside users.
The second conduit permits access to GRE. Step 4 Add the remaining static and conduit statements to let the dmz1 and dmz2 interfaces access the mail server on the inside interface:. These statements create a global address on each interface to map to the inside mail server and then create a conduit so that users on each interface can access the mail server via the SMTP port Step 5 Let users know how to access the server.
Users on the inside access the server at Step 1 Add statements to let users on the various interfaces access the web server on dmz The static and conduit statements work the same way as described before for the mail server, creating a global address through which users on the interface can access the web server.
The global command adds a new dimension to server access. Because the inside interface is at a higher security level than the dmz2 interface, instead of using the static and conduit commands to permit access, you use the nat and global commands. The nat statement is probably a redundancy because your configuration should already have this command as described in the section " Step 6 - Let Users Start Connections "—do not enter this command twice in the configuration.
The nat statement lets inside users start connections on any interface of a lower security level; therefore, they can access the dmz2 interface. The global command lets the inside users translate their connections to access the address of the web server on the dmz2 interface. Step 2 Let users know what IP address to access the server. For users on the inside interface, they would access the web server at address Users on dmz1 would access it at Specify a static route for each network connected to any router.
Refer to the section " Step 7 - Create a Default Route " for information on default routes, and to the section " Step 3 - Configure Network Routing " for information on configuring routers and hosts for default routes. Step 1 Sketch out a diagram of your network, for example:.
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