Cisco Firewall :: 1921 - IOS Firewall (ZBF) Limit SMTP Connections From Same IP
Mar 14, 2013
IOS Firewall (ZBF) Limit SMTP connections from same IP
we are running a Postfix MTA behind a IOS Firewall (ZBF) on a CISCO1921. Sometimes we get more than 2000 smtp login attemps like
postfix/smtpd[123456]: connect from (...) (...) postfix/smtpd[123456]: lost connection after AUTH from (...)
in one second. May be bruteforce or DoS ... nevertheless - we like to protect the Postfix MTA from this stuff.
Can we inspect the smtp and limit connections in a time period from the the same IP? Something like "not more than 10 smtp connections during 60 seconds from the same ip" .
RV082 - 1.3.2 I need to have RDP and pcAnywhere enabled to a customer site for remote support, but need to limit the incoming IP ranges to only our offices. I have the port forwarding set up and tested working. I then set up rules to deny all traffic on the needed ports and added rules to allow a few IP ranges from our office locations. I even tried a rule allowing all traffic from our main office but that also failed to allow RDP or pcAnywere connections.Now I can no longer connect from any of our remote offices. I followed the limited instructions that I found in another post but its not working.
I'm trying to determine whether Cisco has any equivalent (in any platform) to some of the existing firewall rules within our iptables infrastructure. [code] What this does, is allow port forwards on port 3389/rdp. However, if a single IP opens too many connections within a timeframe, it starts dropping new ones.This is a critical requirements for certain security scenarios, such as preventing RDP brute forcing. A similar principle can be applied to 22/ssh.I've had a look around, rate limiting searches generally land me on QoS based discussions. I've seen people ask similar questions and get referred to CBAC. Whilst I can see similarly worded functions there such as limiting "half open" connections, I don't see anything there that limits the actual number of connection attempts you can make.
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.
I have an ASA 5500 Firewall. I need to figure out how to log all events using Port 25 to determine if there are any rogue devices on our network. I was trying to figure out how to do this via the Real-Time Monitoring (filter) but have had no success.
Most examples of NAT translation using an ASA 8.4 are based on servers within a DMZ. In my case it's not because the mailserver also functions as an data and Active Directory server for my local domain. If tried to config the ASA for a while now and throw it in the corner for a couple of months out of frustration. Now I got some time left during christmas break I decided to start again.My purpose is to NAT SMTP / POP traffic from the internet, trough the ASA to my (inside) server. This is what I got so far. With this config I'm unable to telnet the inside server (192.168.1.10) from a remote location.
I can ping 192.168.1.10 from the ASA CLI. I can Ping DNS 4.2.2.2 from the CLI (internet access). I can Telnet the server from the inside LAN, using: telnet 192.168.1.10 25.But I can't Telnet from an outside location using: Telnet 95.*.*.218 25 Because my server is on the Inside interface (diffenrent subnet) do I need an additional route?
I have a ASA 5510 (ver 8.4) and I have been all over the support sites looking for what I am doing wrong. I have a sanitized cut n paste of the OBJECT, NAT, ACCESS-LIST and Packet Tracer output and it keeps failing on the NAT with a rpf-check. Once i get the SMTP flowing I have to open up HTTP and HTTPS to one of the servers also.
Here it is:
RVGW# sh run object object network WiFi subnet 172.17.100.0 255.255.255.0
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.
I'm new to ASA's and PIX units. I've setup a few VPN's now but know next to nothing about logging on these units. I read the config guide for the PIX, but cannot figure out how to get a log of incoming SMTP traffic going on the console.Do I need to use a SYSLOG server? I can probably set one up on my laptop.
I'm trying to configure a simple ACL to block smtp traffic from leaving my LAN -- basically prevent internal users from setting up internet email accounts in their email clients and sending through that smtp server. i want my Exchange server only to send smtp traffic. here's what i have:
-access-list 102 extended permit tcp host 10.10.1.29 eq smtp any eq smtp <===10.10.1.29 is Exchange
-access-list 102 extended deny tcp any eq smtp any eq smtp
-access-list 102 extended permit ip any any
-access-group 102 in interface inside
after i apply this ACL to the ASA, i am still able to send from my internet email address setup in Outlook using my "foreign" smtp server.
I have an issue with my mail server(SME Server) which is behind a Cisco ASA 5500(firewall) problem is that if one leaves my network they can receive but can not send email via my SMTP also internal people can only send if they use the IP address of the server rather than the domain [URL]
We have hosted spam filter service with 3rd party vendor. My vendor is switching to different spamming services and I need to add ip address lets say 44.33.454.32 to the list of allowed system that can connect to my smtp service. I am going over my firewall 5510 configs and I think I need add the entry like this: “access-list outside-to-inside extended permit tcp object-group obj-44.33.454.32 interface outside eq smtp”. [code]
We have an ASA5510 with the IPS ASA-SSM-10 module installed. All is working well except event notification. When sending a test email from the SSM IPS, we get the error "could not connect to SMTP host". The Exchange SMTP host does allow traffic from the IPS and ASA. I can ping to the SMTP host by IP and name. What am I missing here?
Just doing some basic testing before we replace our ancient PIX 515E with a new 5512. I have a mini lab set up following the diagram below, although I am unable to telnet through to the mail server's netcat listener on port 25 TCP. I can ping all the way outbound from 192.168.101.1 to 10.0.0.2, and the 10.0.0.2 machine shows it is translated properly to 200.225.117.1.
NAT and access rules are as follows:
object network mail host 192.168.101.1 description Mail relay access-list inbound extended permit ip any host 200.225.117.1
[code]....
EDIT: Somehow the new global access rule is involved. When adding a permit any any in there I can get to the mail server no problem. When I remove it but leave in my permit ip any any on the outside interface, I am denied?
Using an ASA5505, have 1 static outside address, want to access an inside SBS-Server on SMTP, RDP (3389), HTTPS and port 987
Have configured network object nat rules using the asdm, SMTP works (I can telnet to the server on port 25 from outside), however for some reason I can not telnet inside and out on port 25, so outgoing mail does not work. RDP does not seem to work from outside, 987 I havent tested from outside. When I try to create a network object nat rule for https I get this message from the ASA:
We have a 5510 (8.2) with the following 4 interfaces (security-levels) inside (95), outside(0), dmz(25), and test (95). The dmz network is 10.10.10.0/24 and the outside interface is 40.133.84.69.We have run into a situation where a dmz hosted iRedMail server running postfix (10.10.10.51) is relaying mail which in some cases points back to us at 40.133.84.69 and into our Exchange server. In these cases in the dmz server's mail logs we see postfix timeout trying to connect to smtp at 40.133.84.69. When I try to telnet from 10.10.10.51 to the outside interface on port 25 it times out.We've tried different ways to allow the outside adapter to permit smtp (or any service!) from 10.10.10.51 but we're left scratching out heads.
how to go about setting up the ASA to block any SMTP traffic outbound except for our Exchange Server. This is in relationship to a SpamBot issue that blacklisted us. I have an ASA 5510 running version 6.2(5) / 8.2(2) with three ports. DMZ, Inside and the Outside interface. Up till today, I only needed to block outside traffic to our internal network which I used the ASDM to configure a rule on the outside interface for an incoming rule. I am assuming I need to create an outgoing rule on the outside interface; however, just to make sure I understand the terminology/traffic flow, I created the rule with my computer as the source (192.168.0.131) with ALL destination and the service as HTTP. My logic, which seems to fail here, is that any traffic from my computer going outbound would be blocked; however I am still able to browse... That said, if I were to change the source as the Exchange server and the Service Type to SMTP, it would not actually block traffic and therefore not solve our problem. I even gone as far as permitting traffic from my computer, expanding the hit counter and I see no hits. So I am no doubt doing this wrong. What I do know, is when I first created the rule, a second rule was automatically created (Implicit rule) that deny all sources and blocked all HTTP traffic until I changed it to Permit?
i cannot send emails to outside, i have an access rule on interface inside permit source: inside destination: any servic: tcp/smtp and when i make paket tracer it shows me that the packet is dropped but i cant see through which rule!!
A recently added outbound rule has left my SMTP communications broken. I have since removed the rule, and had Cisco do some damage control, but it's still dropping some of the SMTP traffic. I get a number of NDR messages each day like the one below:Your message did not reach some or all of the intended recipients. Subject: RE: Christopher, Curt Sent: 8/19/2011 9:38 AM The following recipient(s) could not be reached:
[URL] on 8/21/2011 9:49 AM Could not deliver the message in the time limit specified. Please retry or contact your administrator. <630.SM.Local #4.4.7>
Your message did not reach some or all of the intended recipients. Subject: RE: Christopher Curd Sent: 8/19/2011 9:38 AM The following recipient(s) could not be reached: JWillar@email.com on 8/21/2011 9:49 AM Could not deliver the message in the time limit specified. Please retry or contact your administrator. <630.SM.Local #4.4.7>
I've attached an image of my configuration (ASDM GUI). The part of the image highlighted in green are the SMTP rules. The part highlighted in yellow is another rule that I added about a month ago to block a SYN attack. This rule may be part of the problem because of the order it is in the list. Not sure, though.
I have had two Cisco techs Putty into my ASA to check things out. I think they've done all they can. I wonder at this point if it be wise to just reload the last good running-config I have prior to the Outbound rule being added.
Up until recently one of my sites was able to get to a postilion subnet. Then we started receiving "host unreachable" e-mails. Posting told us SMTP traffic was not getting let in. I've compared the current config to a config that was saved before the issue popped up and found really no noticeable difference.
I tried a packet tracer trace with no luck: SiteB- Firewall# packet-tracer input outside tcp 11.2.2.36 12345 65.19.0.0 25.
Phase: 1 Type: FLOW-LOOKUP Subtype: Result: ALLOW Config: Additional Information: Found no matching flow, creating a new flow [code]...
Result: input-interface: outside input-status: up input-line-status: up output-interface: outside output-status: up output-line-status: up Action: drop Drop-reason: (acl-drop) Flow is denied by configured rule
Attached is a sanitized config. I'm not entirely convinced it's a firewall issue, but I need to some successful testing to prove otherwise.
I 've got some problem with my Mail Server since I've migrated to an ASA5510.Actually the server is in a DMZ with a private Ip ( 10.x.x.2) and it is translated to a Public IP ( 194.x.x.65).Some Users received in there mailbox a system administor error message :Object : Impossible to deliver : testYour message could not be deliver to one or more of its recipients: 421 SMTP connection went away!When they try to re sent it some times later, message is sent whithout problem.
We are using several Cisco ASA 5505 with the 8.05 OS on it. The problem is that the SMTP traffic of my ISP(Telenet) isn't passtrough the ASA, I'm using outlook 2010. Before there was also a problem with our local exchange server but I solved this by disabling ESMTP checking in the policies, but it didn't worked for my local ISP.
I am new to the ASA series and I am at a complete loss as to why I cannot configure this router to forward SMTP and RDP traffic to an internal host.
The packet trace tool in ASDM shows complete end-to-end connectivity for RDP but it still fails to connect from outside. This is my config file, what I need to change in order to make it work?
I have an ASA 5510, one public IP address on my outside interface, an internal email server and a private network.I would like...
1: Users on my private network to be able to access the internet (PAT them to external outside address) 2: Email to be delivered to my MX (my single public IP address translated back to my internal email server.
i.e. can I share my single public IP address to serve translation in both directions (private users surfing the Internet (in-to-out) and an outside to inside NAT for email) ?
Email (MX) = 1.2.3.4 Public (outside) address = 1.2.3.4 Email server internal = 10.1.2.3 Internal private subnet for users = 10.0.0.0/8
We have configured ASA 5510. We have configure Ethernet 0/0 ( Outside ) connected with ADSL line and Ethernet 0/1 ( Inside ) Local LAN. we have configured NAT and all the traffic is passing through outside interface. Now we have connected ethernet 0/3 ( leasedline ) interface with static public IP. Now we want to allow SMTP traffic to pass through from this interface.
How to configure it if we want our local lan SMTP traffic sending through new leased line ( Static Public IP ).
I have a 1921 k9 router that has several DHCP pools configured. Before implementing the firewall they were all working. After implementing it they stopped working. I messed around and got the routed port GE0/1 handing out IP addresses and left it alone. Somehow it quit handing out IP addresses yesterday.I dont know if its a quick fix or not (getting DHCP working on the interfaces) but if any article that will walk me through getting DHCP working on all of the interfaces. [code]
We have 3 sets of applications. The first does not require much bandwidth but is very critical, the other two is more bandwidth consuming but less critical. I would like to know if it's possible to reflect this priorities on the router configuration. Is it possible to set the ports 10000, 10001 and 10002 of the external IP have higher priority to be handled, for example? Also, is it possible to limit the bandwidth that goes through a set of ports?
I must prevent the 2 sets of less critical applications to strugle the critical ones. What router can provide this capabilities? Is the 1921 able to do this job?
We purchased a cisco 1921 router to replace a software firwall not long ago. The router was sold as a firewall with the suggestion that an ASA would be unnecessary.Unfortunately a router does not replace/do the jobs a firewall does, so I looked online and noticed that Cisco do offer firweall security features in one of their IOS.How do I tell if this is implemented on my router?If not, does my IOS support this, or do I need to buy an extension/another version of the IOS?,The version of the IOS I have is: c1900-universalk9-mz.SPA.151-4.M4.bin.
I have a 1921 K9 with a 4 port 10/100/1000 EHWIC switch.
Interface 0/1 = 192.168.1.0 EHWIC = 192.168.5.0
I have Active Directory setup on the 192.168.1.0 network. When I attempt to join the domain from 192.168.5.0 it joins but I get errors. After some troubleshooting using portqry I have found that the services related to class map DomainTrafficUDP are being reported by portqry as being filtered regardless of policy map settings (currently set to allow).
Building configuration...
Current configuration : 18833 bytes ! ! Last configuration change at 11:20:25 NewYork Thu Apr 19 2012 by dave ! NVRAM config last updated at 13:56:45 NewYork Wed Apr 18 2012 by dave !
