Cisco Firewall :: ASA5510 ESMTP Inspection Stopping Outbound Mail
Jun 13, 2011
I am having an issue with an ASA 5510, running 8.4(1) code, causing outbound mail to remain in the SMTP server queue (Exchange 2007). This only happens with some remote mail servers. The connection usually ends with the remote server eventually sending a TCP reset.
I've taken multiple inside and outside packet traces.Other trace's contain either X's preceding various sections of the stream content or all X's in the content. The X's only appear when inspection is enabled.
Disabling inspection is the only thing that seems to allow mail to flow. I find this curious because I'm running this same ESMTP policy on other ASA's. However, they are on 8.3 code.
Most everything I find when searching on this subject says to disable ESMTP inspection. [code]
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Jan 14, 2013
I have a client that is running an ASA5512-X. When I initially installed it, they were having issues sending out emails. I disabled ESMTP inspection and thought it resolved the issue. Recently, they upgraded to Exchange 2010 and are still having an issue with some emails getting hung up in the queue. If I watch the ASA when they try to telnet to the external mail servers that do not work, they get a SYN timeout.
I am not sure why this would happen since ESMTP is disabled. They are running 8.6(1) on the ASA.
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Aug 9, 2012
We have several customers running ASA 8.4x code and all seem to be plagued with the ESMTP inspection bug CSCtr92976.I have tested this in the lab with an ASA 5505 running 8.4(1), 8.4(2) and 8.4(4)1 & 8.4(4)3 and the behaviour is always the same. I have an Exchange 2007 server and I can see in the logs the following messages:
2012-08-10T13:04:37.331Z,EXCHANGEDefault EXCHANGE,08CF3610468A42D7,3,192.168.102.28:25,192.168.250.26:52756,<,XXXX XXXXXXXXXXXXXXX,
2012-08-10T13:04:42.345Z,EXCHANGEDefault EXCHANGE,08CF3610468A42D7,4,192.168.102.28:25,192.168.250.26:52756,>,500 5.3.3 Unrecognizedcommand, 2012-08-10T13:05:20.506Z,EXCHANGEDefault EXCHANGE,08CF3610468A42D7,5,192.168.102.28:25,192.168.250.26:52756,<,XXX,
This is with the default ESMTP inspection enabled. I have also created a custom ESMTP inspection policy that does nothing but log and the behaviour is still the same. Sometimes traffic will pass but most of the time it won't. The workaround is to just disable the ESMTP inspection.
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Dec 26, 2011
I’m trying to configure my ASA 5505, in order to allow my inbound and outbound mail communications. Here with this mail I’ve attached a diagram which illustrates my exact network setup along with ip addresses.
In this setup I’ve enabled port forwarding on my ADSL router (port 25 and 110) and configured the ASA accordingly, and my mail server is located inside my network.
My problem is currently I can send mails from my inside network to outside but my not receiving any mails which originate from outside. I’ve attached my current ASA configuration as well,
C:UsersSuthakarDocumentsOffice_DocsThakralABC Computers
Final config on ASA5505
host name Cisco
enable password 8Ry2YjIyt7RRXU24 encrypted
password 2KFQnbNIdI.2KYOU encrypted
names
!interface Vlan1
nameif inside
security-level 100
ip address 192.168.155.201 255.255.255.0
[Code] ......
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Jun 13, 2012
I am using the Cisco ASA5510 for my Telepresent infarstructure. I have a problem with Encrypted SIP calling for call in/out.
Is there is a way to disable the TLS inspection for Cisco ASA5510?
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Jun 15, 2011
My mail server is not in my network, it's over internet elsewhere.After installing the ASA 5510, i can not get my mails any more.
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May 30, 2013
We are working with an ASA 5520 and it seems there is an issue with some email messages sent throught it. When there are many recipients in the emails the email messages are not sent, and I have revised the server an the only thing I see is connecting dropped. When I went to see ASA log and see this log report: ESMTP Classification: Dropped connection for ESMTP Request from 'interface': servername/portnumber to outside: IP address/25; matched Class 2: cmd RCPT count gt 100 tcp flow from interface:servername/portnumber to outside: IP address/25 terminated by inspection engine, reason - inspector disconnected, dropped packet. So I think there should be an inspection of ESMTP packets and if they detect an email message sent to over 100 addresses, then the packet is dropped, am I right? if so, what should I do to let those email messages be sent?
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Jun 10, 2012
We have a main office and 4 remote offices (only showing 1 remote office in the diagram). We are using GRE over IPSec VPNs to the remote offices which terminate on the 2811 router in the main office. We are using the 2811 as it is the only device that we have that can terminate GRE. The 2811 router is connected to the outside switch and is configured with a public IP address. We also have a ASA5510 in the main office which is connected in the same manner and is used for Web, e-mail traffic etc.Both the main office and remote offices have a 10Mbps Internet connection.
We have an issue with voice quality between sites as we are finding it difficult to control bandwidth utilization in the main office. When users in the main office download web content it can saturate the 10Mbps Internet connection causing voice quality issues. We have configured outbound shaping on the branch routers to make sure that aggregate inbound traffic from all branches to the main office does not saturate the link but we cannot control traffic from the Internet.I understand that controlling inbound traffic from the Internet is difficult without controlling QoS on the ISPs side. Is there any way that can reserve inbound bandwidth to ensure that web traffic does not impact voice? Also in this design, which is the best place to configure outbound QoS from the main office?
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Nov 11, 2012
The other day I set up a firewall on my Cisco 1841 router, it all seems to work fine except for a few small problems. 2 wireless devices an iPhone and an Android tablet are having some problems with 1 or 2 apps. iPhone 6.0.1 Facebook app and the App store will not load Android tablet ICS BBC iPlayer and Google play app store wont load or play content. Both devices with their issue were working fine until the new firewall was installed. I’ve tried opening ports and adding ACLs but nothing seems to work. I’ve included my start up config. All other PCs, laptops, smartphones and iPads work fine.
Building configuration...
Current configuration : 5551 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
[code].....
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Nov 26, 2012
The other day I set up a firewall on my Cisco 1841 router, it all seems to work fine except for a few small problems. 2 wireless devices an iPhone and an Android tablet are having some problems with 1 or 2 apps. iPhone 6.0.1Facebook app and the App store will not load Android tablet ICS BBC iPlayer and Google play app store wont load or play content. Both devices with their issue were working fine until the new firewall was installed. I’ve tried opening ports and adding ACLs but nothing seems to work. I’ve included my start up config. All other PCs, laptops, smartphones and iPads work fine.
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Aug 2, 2011
We had a problem with SMTP inspection dropping some regular emails (Cisco 2901 IOS 15.0). The original configuration.
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Jun 21, 2011
We had a problem with SMTP inspection dropping some regular emails (Cisco 2901 IOS 15.0).Incoming mails are going thru Spam and Virus Blocker so that bypassing SMTP inspection is not security issue in this case.
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May 25, 2011
I have multiple customers and servers behind my ASA5510s. After moving a new customer with an FTP server behind the firewalls, they immediatly had issues with customers connecting to their FTP server. I had the default inspection rules running regarding FTP. After removing the "inspect ftp" from the global policy their issues went away. Since this is a larger customer I can't force them to change their server, I need to accomodate and fix this on the firewall. I left the "inspect ftp" command out and there have been sporatic issues from other customers, unable to connect to outside FTP servers from the terminal servers and timeouts and disconnects to our own FTP servers.
This is what I "think" is the solution.. I added a second inspection policy after the default one and only added "inspect ftp" to it. Then I used the "exclude" option to exclude the new customer. That new customer is fine and things are better, but still not working right. Does the following config accomplish what I want?? Does the exclude ACL get what I need or do I need an "include" or permit statement in that ACL?
object-group network DM_INLINE_NETWORK_10 network-object 172.24.X.0 255.255.255.0
object-group service DM_INLINE_TCP_1 tcp port-object eq ftp port-object eq ftp-data
access-list global_mpc extended deny tcp any object-group DM_INLINE_TCP_1 object-group DM_INLINE_NETWORK_10(code)
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Jan 29, 2013
ASA 5520 running 8.4.5:We had an issue with a remote SMTP connection getting screwed up as a result of ESMPT inspect.It took me 3 hours of troubleshooting the SMTP connection before finally figuring out that the firewall was the culprit. What really through me off was that I saw nothing in the ASA logs (warning and above) that showed packets were being dropped. I'm probably crazy but I thought I remembered seeing entries in the log when packets were dropped due to a type of inspection (specifically, I remember entries in the log saying something to the effect of packet dropped due to ESMPT inspect, packet too big). My quesiton to Cisco TAC was: Is there a simple way to have the log give a warning every time a packet is dropped due to any inspection rule, just like we can see any drops due to ACLs? So far the only answer has been a complex list of log changes to allow debugging and notifications of certain events. This isn't something I want to roll out to all my ASAs.
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Sep 21, 2011
By default ASA applies DNS packet inspection with a default (maximum) packet size of 512bytes as recommended by RFC 1035, anything above is dropped.
I have a customer that is trying to use larger packet sizes due to extension mechanisms for DNS defined in RFC2671.
My question is , is it safe to increase the default packet size in the DNS inspection thus applied globally for all DNS traffic, or should / can we apply a policy that applies only to this specific customer ?
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May 3, 2011
let me know how to enable HTTP inspection in ASA 5505 through ASDM.
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May 9, 2012
I was under the impression that all Cisco ASA firewalls shipped with a default inspection policy.
Example
policy-map global_policy
class inspection_default
inspect dns preset_dns_map
[Code]......
can I build this myself? Why is it missing (I have two other ASA 5505s here that also do not have it). What would I do to rebuild it?
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Jan 10, 2011
On FWSM (running version 4.1 in my case) the default global policy uses the following class map:class-map inspection_default match default-inspection-traffic
What "default-inspection-traffic" includes? Is it all traffic? If so, do I really want all my traffic to go through the inspection engine? I would imagine this would have a performance impact on traffic that is not part of the protocols being inspected.
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Jul 16, 2009
I have an issue with Cisco ASA 5520, The summary is below!
Packet # 1 on inside capture the Call-ID was: Call-ID: 2a54f680-
a5d1de2a-160c-164070a@10.7.100.1
Packet # 1 on outside interface the Call-ID was: Call-ID: 2a54f680-
a5d1de2a-160c-164070a@149.5.33.44 --- this bcz of the inspection.
Packet # 2 on outside capture the Call-ID was: Call-ID: 2a54f680-
a5d1de2a-160c-164070a@149.5.33.44
Packet # 2 on inside capture the Call-ID stay: Call-ID: 2a54f680-
a5d1de2a-160c-164070a@149.5.33.44 --- this is the problem.
(This suppose to be Call-ID: 2a54f680-a5d1de2a-160c-164070a@10.7.100.1)The inspection should change the Call-ID for the incoming packet as it did with the outgoing packet. Whenever, the CM receive the trying message with different Call-ID it considered as new session and it keep sending invitation messages for the SIP provider.NAT is enabled.
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Jan 18, 2012
I am having issues with PXE boot images for PCs cannot be loaded from remotely.The diagnosis revealed that SunRPC & TFTP were being inspected by ASA causing drop of packets.So I excluded these two inspections for the particular server behind the firewall. It seem to resolve the issue for instance but it crawled back again.
Is there a way that the inspection can be turned off for that particular server at the IP level?
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Dec 31, 2011
I have a branch office set up were all traffic goes back to the core, iincluding internet acces.
It has been working fine for a year, but recently I have started to see the firewalls Asa 5505 closing the connection and stopping the phone from answering the calls.
I have skinny inspection turned on all my branch offices, but had to turn it off at the one site to get one of my phones to registered.
I haven't made any changes to the network that would trigger this issue, such as upgrading phone firmware.
My firewall is configured for default deny, other than Skinny (tcp 2000), do I need Skinny inspection to be turned on?
It's turned on my 5 other branches.How can I debug why the skinny inspection is closing the connection?As a separate note this phone is part of a pool of phones that shares a common DN, would this be causing the issue?
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Mar 8, 2011
I Have a 2821 Router with a IOS Version 12.4(13r)T. When i enabled the firewall, my download speed slows down to 10-20kbps (the normal is 5-6 Mbps).
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Jun 5, 2012
I need to allow traffic between webserver in dmz and mssql (Microsoft SQL Server 2008).MSSQL use dynamic port (now it is 63796) and this cannot be changed.
Basically, I can allow such traffic using next configuration:access-list dmz extended permit tcp host 1.2.3.4 host 5.6.7.8 eq 1433access-list dmz extended permit udp host 1.2.3.4 host 5.6.7.8 eq 1434 access-list dmz extended permit tcp host 1.2.3.4 host 5.6.7.8 eq 63796
But, I would like to add mssql inspection and I did the next:
class-map class_sqlnetmatch port tcp eq 1433policy-map global_policyclass inspection_default inspect dns preset_dns_map inspect ftp inspect h323 h225 inspect h323 ras inspect ip-options inspect netbios inspect rsh inspect rtsp inspect skinny inspect esmtp inspect sqlnet inspect sunrpc inspect tftp inspect sip inspect xdmcp class class_sqlnet inspect sqlnet service-policy global_policy global
[Code] ..........
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May 6, 2011
I can't find any specific information on the implementation of packet inspection in a zone based policy firewall. In other words, is there a specification or even just a set of values that define the default inspection parameters for all protocols? With DPI I can manage 'some' of the inspection capabilities but I have some fairly rigorous and specific requirements to meet and I need to validate that the IOS ZBFW will meet those requirements. Specifically, I'm interested in HTTP, DNS, and ICMP but all other protocols would be useful as well.I'm working with basic routers; 871's, 2811's, 1841's, etc. The IOS in use in most cases is adventerprisek9-mz.151-3.T.
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May 25, 2011
I currently have the default inspection engine configured in my firewall to inspect http traffic. I noticed that the ASA will drop packets when visting legitimate websites. I've tried googling for a workaround but have been unsucsselful. How can I exclude some websites or IP's from being affected by the inspection engine?
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Sep 7, 2011
verify if the ASA 5520 CSC module way of applying security policy (http, smtp, pop3, etc.) is per network/subnet or group of users? Based on my understanding through reading, web and email protection profile/config is global. It will be the same to every network user that is redirected via service-policy config on the ASA.
Scenario: I have two VLAN, guest and employee. Of course guest and employee have different web filter profile. Can i configure it such that guest web-filter profile is not just strict while employee's access is limited only to productive internet sites.
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Jun 6, 2011
I have problem with icmp traceroute configuration. When I enabling icmp error inspection in global policy, my traceroute results through ASA 8.2.4 looks like this: My traceroute [v0.75]
icmp inspection and ttl decrement on ASA is enabled. Also I configured ACL on outside interface to permit ICMP completely.
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Aug 11, 2011
I'm looking fot a way to do static URL blocking with ASA and when the URL is blocked present a "Web Page" to the user saying that it's been blocked.
So, i was wondering if i can use the http parameter "spoof server string" to replace the original URL sent by the user for another URL that points to an internal web server holding a basic page saying "Your URL request has been blocked".
The point is to have a way to tell users that the page they are trying to browse is blocked by a policy.
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May 10, 2012
i have removed the icmp inspection from my default policy-map in my ASA 5520,now i could not able to ping to 4.2.2.2 from my LAN even though i have configured an ICMP Access-list in my asa like ,but I can't ping 4.2.2.2 for testing the Internet connectivity,what shall i do to allow only my self as admin to ping outside?
-icmp permit host 192.168.60.60 echo
-icmp permit host 192.168.60.60 echo-reply
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Oct 5, 2011
I'm having some issues getting ActiveFTP to pass through an ASA 5505, I finally found out when I tested the FTP via cmd on windows(after the major hassle of getting credentials out of the software co) that it does open the connection on the control port, but whenever I try to send/recieve data the connection is dropped, for troubleshooting purposes I've even gone as far as opening up all ports 1-65535 with an acl to no avail, I believe the FTP traffic is encrypted with SSL(can't get a solid Y/N from the company).
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Mar 30, 2011
Below is the interesting part of my config. I have static NAT configured and working inbound for the Exchange Server and the Barracuda, however outbound traffic from those hosts comes out as the interface IP. Thoughts? I've tried a number of things (outside, inside), etc.
object network obj_any
subnet 0.0.0.0 0.0.0.0
object network DSN-EXCH01
host 10.250.231.51
object network MAIL-IN
host 10.250.231.50(code)
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Jun 6, 2012
ASA 5510 have two model Bun-K9 and Sec-Bun-K9 from the datasheet find out difference Port related and Redundancy. My questions is : Have any major difference for Security service between two model ?
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Jun 23, 2011
I got a problem yesterday with a customer that says that the calls from a CISCO IP Phone 7961 to an Alcatel 4018 IP Touch didn't work, well the phone rings but there's no voice; I manage a CISCO ASA version 8.2(1) and I was checking the Inspection Rules in the Service Policy Rules section and when you open the inspection_default at the Rule Actions tab I find that the H.323 H.225 and H.323 RAS box wasn't checked so I ask to the customer to made a test and the same problem happen so I checked both box and again ask to the customer for a test and it works.
I was talking to a partner and he said that maybe this Inspect fix some signaling parameters of this protocol that can't work fine behind of a firewall.
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