Which interface to apply IOS IPS

Hello,
I have IOS IPS installed on 4 routers on our network at different sites. They are 2911 routers, with 2GB ram and i am using the latest signatures from cisco. Everything is working fine. I have enabled the basic signatures. At the moment the ips policy is only applied to the wan interface and not the lan. So in summary:
interface serial0/0 (wan link)
ip address x.x.x etc
ip ips mypolicy in
ip ips mypolicy out
exit
According to cisco i should not bother applying ip ips mypolicy out on the wan interface (serial0/0) but should have ip ips mypolicy in on the fa0/0
lan interface aswell as the serial0/0 interface.
interface fa0/0 (lan traffic)
NO IPS POLICY IN HERE AT THE MOMENT
anyone got experience on this?
regards
Kevin

Hi Kevin,
I would say that you have done the right thing, since router are limited in memory we should not enable a lot of signatures and also try to limit the scanning to traffic that we actually need to be scanned.
In what you have done any traffic that in entering or leaving the WAN interface will be scanned.
Now if there are more interfaces on your router and you want the traffic between the interfaces to be scanned as well in that case only you should enable IPS on those interfaces.
Most of the times it is not needed.
Regards,
Sachin

Similar Messages

Is there a way to automate IOS IPS signature updates without CSM?

I have a growing number of 891 routers running IOS IDS/IPS. My Cisco vendor has stated repeatedly that CSM is the only way to manage signature updates to multiple routers, but I'm finding CSM to be incredibly tedious and slow. It also wants to manage a lot more than just the IPS policies and signatures which causes other problems.
I have about 160 routers deployed now and that will grow to at least 600. I have CSM 3.3.1. I'm told 4.x would make it easier becasue it can be configured to ignore more of the non-IPS bits of the router configs, but the upgrade is a big chunk of money that wouldn't be in the budget until at least 2012.
Is anybody doing this with an expect script or EEM applets or something else? It seems to me that I could manually upload an update to one router and push the resulting XML files to all the other routers a lot easier and faster than I could "discover" a bunch of routers in CSM (and rediscover them every time we make a CLI change), add the routers to a group, apply updates to a sig policy, lather, rinse, repeat..., not to mention troubleshooting the weird errors and completely wron "warnings" that CSM spews.
Thanks in advance!

From IOS version 15.1(1)T, you can configure the IOS IPS to auto update from cisco.com which would help I believe.
Here is the configuration guide for your reference:
http://www.cisco.com/en/US/docs/ios/sec_data_plane/configuration/guide/sec_ips5_sig_fs_ue_ps10591_TSD_Products_Configuration_Guide_Chapter.html#wp1138659

IOS IPS for blocking IM and P2P

Any recommendations on the best way to use IOS IPS to stop P2P and IM?
I set up a 3845 with 12.3(14)T1 to do this by importing signatures from the latest SDF using SDM. I used the attack-drop, and all IM and P2P signatures I could find. I changed them all to drop and reset. I then applied it to the inside interface of a 3845. I also set up nbar with a drop policy for all P2P traffic.
The configuration caused very slow web response time for users, including blocked pages. Removing the IPS filter made everything work properly again. The router also stopped rebooting periodically.
Is there a recommended way to set this up that does not cause slow performance and reboots?

OK, went back and loaded some upgraded software. Now using 12.4.1 Advanced security IOS on the 3845, and SDM 211. The new 256MB.sdf signature file has all the IM and P2P signatures in it already!
After applying the IPS inbound on the serial interface, I changed the UDP signatures action to drop and the TCP to drop/reset.
Everything appears to be working beautifully. Yahoo and MSN messenger get dropped, as well as the peer to peer requests. I am unable to download Bittorrent. Web access is fast, and there is no hesitation by the router in configuring the IPS.
This appears to be a great solution so far.

IOS IPS/IDS on a BGP Peering Router?

We have a pair of BP peerings between our network and our upstream service provider. Since the peering points are geographically distributed and we run a "cold potato" routing policy on our network we cannot guarantee symmetric routing for traffic exchanged with our upstream service provider.
Yesterday we followed the bouncing ball through the IPS/IDS setup documentation on a Cisco 2901 running 15.2(4)M3 and acting as a BGP speaking peering router at one of our peering points. Immediately the router started throwing %IPS-6-SEND_TCP_PAK and %IPS-6-TIMEOUT_EVENT messages in the logs. We also observed that some upstream service provider web sites became inaccessible to our users. Turning off IPS/IDS on the 2901 restored connectivity for our users to those web sites.
Three questions:
Do the default Cisco IOS IPS/IDS rules assume that the router will see both sides of each TCP session?
Does the Cisco IOS IPS/IDS TCP stream reassembly assume an attack and send TCP RST frames when it doesn't see both sides of a TCP session?
Should we move the Cisco IPS/IDS functionality from the BGP-speaking routers at peering points to our customer sites, as the customer sites are the only places in our network guaranteed to see both sides of a given TCP session? (We already perform NAT on the customer site routers for that reason.)

Hello Bill,
1) Yes, there are some normalizer functions on some IOS-IPS signatures that will behave like that with this scenarios (Asymetric routing not something good to any kind of security device)
2) Yes, it will close the connections, I will definetly need to look for specific actions regarding that but you could just check the IOS IPS Signature statistics on your router , see which is the one triggering the most and then see the action configured for it (and change it if required)
3) If you cannot change that behavior then it would be safe to tell the router is not a good place to set an IPS or any other kind of firewall configuration unless you set with a weaker security policy (useless from a security standard point of view)
Check my blog at http:laguiadelnetworking.com for further information.
Cheers,
Julio Carvajal Segura

IOS IPS and SDM 2.2.a

Hello everybody!,
I have installed a Cisco 2821 Router with 12.4(4)T IOS version. And SDM V2.2.a. (enteprise service IOS image).
The router have 256MB Ram and 64MB flash memory.
From the SDM Interface cannot upload any .sdf file and cannot edit the signatures and tune de IOS IPS.
Do you know how i can fix that problem?.
Thanks for the answers friends.

Hi,
To add more info, here is the info on defect filed on SDM for RCP issue and workaround suggested.
Symptoms:
Issue 1) Installation of SDM version 2.2a or earlier on a router fails with RCP failure message.
Issue 2) "Load File from PC" feature of File Management dialog in SDM version 2.2a or earlier
fails.
Conditions:
These issues will be encountered for IOS images 12.4(4)T and above.
SDM uses RCP for installation operations. This problem occurs because the fix for CSCdu34824 in
recent Cisco IOS releases has changed RCP behavior. Because of this change, if the RCP client
uses a non-privileged port , the router RCP server does not respond and the above issues occur.
Workaround:
1) For Issue 1 :- Use the copy tftp flash command to copy SDM related files from PC to router.
2) For Issue 2 :- Use the copy tftp flash command to copy the required file from PC to router.

IOS IPS Signature-File

Hi Guys,
We have recently purchased a Cisco ISR 2921, and on its docs it is writen that this product has a License for IOS IPS Signatrue File, but on the product Flash Memory there is no IOS IPS Sig-File.   and while i try to download the sig-file from Cisco, it fails.
Can any one tell me where is an alternate way to download the sig-file ?

900 active signatures is quite much for a system that has no dedicated IPS-ressources.
But you can controll which and how many signatures get enabled on your router:
In the following example I first disable all signatures and enable the ones for web-servers. So just decide which signatures you need. But don't forget to monitor your router-ressources.
gw#conf t
Enter configuration commands, one per line. End with CNTL/Z.
gw(config)#ip ips signature-category
gw(config-ips-category)#?
IPS signature category configuration commands:
category Category keyword
exit      Exit from Category Mode
no        Negate or set default values of a command
gw(config-ips-category)#category ?
adware/spyware                Adware/Spyware (more sub-categories)
all                           All Categories
attack                        Attack (more sub-categories)
configurations                Configurations (more sub-categories)
ddos                          DDoS (more sub-categories)
dos                           DoS (more sub-categories)
email                         Email (more sub-categories)
instant_messaging             Instant Messaging (more sub-categories)
ios_ips                       IOS IPS (more sub-categories)
l2/l3/l4_protocol             L2/L3/L4 Protocol (more sub-categories)
network_services              Network Services (more sub-categories)
os                            OS (more sub-categories)
other_services                Other Services (more sub-categories)
p2p                           P2P (more sub-categories)
reconnaissance                Reconnaissance (more sub-categories)
releases                      Releases (more sub-categories)
specially_licensed_signature Specially Licensed Signature (more sub-categories)
telepresence                  TelePresence (more sub-categories)
uc_protection                 UC Protection (more sub-categories)
viruses/worms/trojans         Viruses/Worms/Trojans (more sub-categories)
web_server                    Web Server (more sub-categories)
gw(config-ips-category)#category all
gw(config-ips-category-action)#retire true
gw(config-ips-category-action)#exit
gw(config-ips-category)#category web_server
gw(config-ips-category-action)#?
Category Options for configuration:
alert-severity   Alarm Severity Rating
enabled          Enable Category Signatures
event-action     Action
exit             Exit from Category Actions Mode
fidelity-rating Signature Fidelity Rating
no               Negate or set default values of a command
retired          Retire Category Signatures
gw(config-ips-category-action)#retired false
gw(config-ips-category-action)#exit
gw(config-ips-category)#exit
Do you want to accept these changes? [confirm]
gw(config)#
gw(config)#exit
gw#sh ip ips configuration | s IPS Signature Status
IPS Signature Status
    Total Active Signatures: 131
    Total Inactive Signatures: 4370
gw#
I didn't follow the thread and answered your first post to have less line-breaks in this post.

IOS IPS - Sig 4050 UDP Bomb apparent false alarms?

Hi,
I'm trying the IOS IPS solution out in a lab environment and I seem to be getting lots of false alarms on sig 4050 - UDP bomb. Looking at the signature description via go/mysdn, and looking at it's configuration on the router via SDM, I can see it is simply looking for small UDP packets. But I don't know what size (The parameter is named ShortUDPLength and it's set to True).
All NTP traffic kicks of this signature. Using Ethereal to capture the NTP exchange, I see that the communication in each direction is a single packet. The layer 2 frame lenght is 90 bytes. The UDP data length is 56 bytes. All of this seems fine. The NTP server is a Cisco router. The NTP client is running on a Windows 2000 workstation.
Also, any TFTP to/from the router with IPS enabled also triggers the alert. Specifically it is the Ack's from the TFTP server that trigger the alert. They are indeed small packets - the UDP data size is only 12 bytes.
Note, this same traffic does not cause alerts from a 5.0 IPS sensor. Looking at the signature definition on the sensor, it doesn't have a parameter named SnortUDPLength. Instead it has a parameter named udp-length-mismatch which is set to true. This doesn't seem to be keying off of a particular data size, but instead conflicting reports in the UDP header compared to the actual packet size.
Any information that anyone could provide to shed light on this subject would be appreciated. Such as:
1) Do you find that IOS IPS sig 4050 false alarms are common?
2) What is the UDP data length that triggers the alert? It has to be bigger than 90 bytes!
3) Does Cisco have any recommendations on what to do with this built in signature?
Thanks,
KEP

On the sensor appliance side, the udp-length-mismatch checks for discrepancies between the ip header length and udp length of the packet. You were dead on, the signature triggers when the UDP length specified is less than the IP length specified. I'm not positive of exactly what the IOS ShortUDPLength parameter is.
You provided some valuable information in that the same traffic doesn't trigger the alerts on the appliance, so we know that this is not the signature, but rather the implementation of it in IOS.
I'm taking a bit of a leap here not knowing what IOS version you are running, but I'm guessing you may be running into CSCeh32935. The title states multicast, but the bug is not limited to just multicast traffic. This affectes some 12.3T releases and early 12.4. Looks like 12.4(2)T or higher has fixes implemented.
Since you're in a lab environment, I'd go ahead and upgrade the IOS on the router and see if that doesn't resolve the issue. If it's still there, open up a TAC case, and they'll be able to recreate the issue and file a new bug if neccessary.

IOS IPS 3845 router

The IOS IPS keeps failing. For some reason it sends the alerts to MARS and then all of a sudden the IPS is disabled on the interface. This config. was down through SDM.

CS-MARS also integrates tightly with Cisco's premier security management suite, Cisco Security Manager (CSM). This tight integration maps traffic-related syslog messages to the firewall policies defined in CSM that triggered the event. Policy lookup enables rapid, round-trip analysis for troubleshooting firewall configuration-related network problems, policy configuration errors, and fine-tuning defined policies.
http://www.cisco.com/en/US/products/hw/vpndevc/ps4077/prod_tech_notes_list.html

IOS IPS - Reset Conection

Hi,
IOS IPS was configured to only generate alert. During testing it was observed that the IPS was reset in giving connections.
log below:
*Oct 10 14:30:29: %IPS-6-SEND_TCP_PAK: Sending TCP packet:(X.X.X.X:433)=>(y.y.y.y:63170),tcp flag:0x4, pak:0x2166449C, iso:0x3D5C7160,tcp seq:0x0, tcp ack:0x0, tcp_window:8192, ip_checksum:0x44B8, Serial0/0/0.1,feat_flags:0x10000, fast_path(no)
Some time ago cisco identified a bug in earlier versions. After opening some TAC, suggested upgrading the IOS and subscription packages.
Cisco recommendation below:
IOS Version : c2900-universalk9-mz.SPA.153-3.M.bin
Packet sig: OS-S744-CLI.pkg
Configuration Cisco Router
ip ips config location flash:ips retries 1
ip ips notify SDEE
ip ips name iosips
ip ips signature-category
category all
   retired true
category ios_ips basic
   retired false
   event-action produce-alert
Could anyone tell how to solve this problem?
BestRegards
Rodolfo Navero

But it will make the warnings go away, right?
but still see the reset command sh ip ips statics.
It seems the problem is in the subsystem of the feature.
I used up the hidden command on the router, but not solved the problem.
csdb tcp reassembly max-queue-length
Interfaces configured for ips 1
Session creations since subsystem startup or last reset 240
Current session counts (estab/half-open/terminating) [7:17:0]
Maxever session counts (estab/half-open/terminating) [10:59:1]
Last session created 00:00:01
Last statistic reset 00:04:15
TCP reassembly statistics
Out-of-order packets dropped 0
++++++++++++++++++++++++++++++++++++++++++++++++++++++++
I performed some tests.
When I make disable all signatures, presents no reset.
However when I enable a single signature, the reset continues.
I believe Cisco has a bug in the compilation of feature
sh ip ips statistics
Interfaces configured for ips 1
Session creations since subsystem startup or last reset 0
Current session counts (estab/half-open/terminating) [4:3:0]
Maxever session counts (estab/half-open/terminating) [4:3:0]
Last session created 00:23:36
Last statistic reset 00:15:40
TCP reassembly statistics
Out-of-order packets dropped 0
Regards
Rodolfo Navero

IOS IPS Important Notice - UPDATED

IOS IPS customers running version 12.4T, 15.0M, or 15.1M - a critical software defect has been identified which may cause your router to reload and be stuck in a boot loop if IOS IPS signature version S639 or later is installed on the device. Recovery of impacted devices is possible only via a serial console connection through the device's ROMMON mode. For customers who are using IOS IPS signatures S638 or earlier, there is no issue. Customers wishing to upgrade the IOS IPS signature version to S639 or later must first be running a fixed version of IOS on the device prior to upgrading the IPS signatures. Fixed versions of IOS include: 15.2(4)M, 15.1(3)T4, 15.2(3)T1, 15.1(4)M5, 12.4(24)T8 and later. Please refer to defect CSCtz27137 for additional details and steps to recover impacted devices.
If you have upgraded your version of IOS to 15.2(4)M, 15.1(3)T4, 15.2(3)T1, 15.1(4)M5, 12.4(24)T8 or later you can obtain the most recent signature updates by contacting the Cisco TAC

What is the most recent version of IOS IPS sig file that TAC can supply?
I'm running IOS 15.2(4)M1 and, per your suggestion above to contact TAC for the most recent signature update, I requested a later version of IPS sig than S636.
I was simply referred back to the standard download page and IPS sig file S636.

IOS IPS Signatures for password guessing?

I recently experienced a password-guessing attack. The inside Windows server's security was pretty well useless in stopping the attack (block, yes; stop, no), because the user ID kept changing, and Windows account lockout ignores source addresses. In this case, it was FTP, and I found an IPS signature for that, but it got me to thinking:
There don't seem to be password-guessing signatures for RDP, HTTP, HTTPS, or SSL. Granted it may not be practical for HTTPS and SSL, but what about the other two? Should we consider rolling our own?

You can configure custom signatures for IOS IPS using Security Monitor which is part of VMS. Below is a doc on how to do this:
http://www.cisco.com/en/US/products/sw/cscowork/ps3990/products_user_guide_chapter09186a0080104f44.html#xtocid9
Also try this link for Cisco Security Advisory
http://www.cisco.com/en/US/products/products_security_advisory09186a008055dbdd.shtml

IOS IPS auto-update without CSM

Hi,
We have 400 x 1811 router on which we need to update the IPS signature definition and custom signature.
What is the best way to do it withou running CSM ?
According to Cisco documentation, we need to add the auto-update command with an .XML extention. But when we load a .pkg in a router, the output is 4 different files. Unfortunalty we can auto-update only one file. Which one to I need to load on our TFTP server ?
All the exemples of Cisco are using one single XML file.
Does a single file with the signature defenition, category, default and type exist ?
Since all our router have the same IPS config, I tought I could use one router at the central office with the configuration we want. And by someway asking the remote routers to auto-update their XML file on that router on which I would have activated a TFTP server.
Anyone ever had to upgrade a lot of router IOS IPS signature?

This can now be done in the 15.1T branch using cisco.com to download the update directly, see :
http://www.cisco.com/en/US/docs/ios/15_1/release/notes/151TNEWF.html#wp1040750
http://www.cisco.com/en/US/docs/ios/sec_data_plane/configuration/guide/sec_ips5_sig_fs_ue.html#wp1137583

1841 IOS IPS online updates

Hi,
Can we configure 1841 IOS IPS to get automatic signature updates directly from cisco site. I know we can do it in other firewalls like sonicwall, fortigate, etc.
Regards
Siva K

Hi Siva,
Yes you can do it from the Cisco Security Manager , or you can try
Automatic Signature Update Guidelines
When enabling automatic signature updates, it is recommended that you ensure
the following configuration guidelines have been met:
* The router's clock is set up with the proper relative time.
*The frequency for Cisco IOS IPS to obtain updated signature information has
been defined.
*The URL in which to retrieve the Cisco IOS IPS signature configuration files
has been specified.
*Optionally, the username and password for which to access the files from the
server have been specified.
SUMMARY STEPS
1. enable
2. configure terminal
3. ip ips auto-update
4. occur-at min:hour date day
5. username name password password
6. url url
7. exit
8. show ip ips auto-update
http://www.cisco.com/en/US/docs/ios/sec_data_plane/configuration/guide/sec_ips5_sig_fs_ue_ps6350_TSD_Products_Configuration_Guide_Chapter.html#wp1079125
regards
Yesua

On which interface should i open ports?

Hi!
Got a case from a customer. They want me to open some ports so that one client can use some applications.
The problem is, I am not sure on which interface i should open the ports. The customer have about 10 interfaces on the ASA. It's a client on the inside network and it should be able to talk to internet through the ports, and anyone on the internet should be able to reach the client on the same ports.
The client uses a static IP.
Sent from Cisco Technical Support iPad App

Hi,
You need to map the flow of traffic for your customer. That way you can plan the changes without breaking anything.
It could be as simple as creating ACL's for the inside and outside interfaces + nat or something more complex.

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Which interface to apply IOS IPS

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