Asa blocking dns traffic. If I set my nslookup server to 8.

Asa blocking dns traffic • DNS Guard is enabled, so the ASA tears down the DNS session associated with a DNS query as soon as the DNS reply is forwarded by the ASA. Just a small point; when your internal DNS uses forwarders, this is a recursive query, meaning that your servers only queries the configured forwarders and those do all the job or the heavy lifting and they get back to your DNS server with the final answer, if you use opendns as forwarder only traffic to opendns should be allowed, when it comes Step 5 (Optional) Block traffic manually based on syslog message information. Any insight is appreciated. behind these firewalls i have one router only to route traffic/switch traffic between two hops (Firewall Inside IPs). 200) ASA5520(config)# route outside 0. I have applied the "nodhcpout" acl to both inside and outside interfaces, but the traffic still passes. 5 > domain controller (exchange) 10. To disable the same-security traffic, use the no form of this command. bin boot system disk0:/asa802-k8. Lets assume that we want to block some specific websites. Unlike tcp which has a session id, etc, and icmp echo is not associate with the icmp response. You could, for instance, use the firewall to force DNS traffic to your preferred resolver. inspect dns preset_dns_map . Note: HTTPS filtering is not supported on ASA. inspect skinny . How do I block all traffic to that 53 port from outside since i need this DNS only inside my NAT/Overload network. DNS CnC: Collection of domain names that are identified as the controll servers for a known Botnet. since i am using 5515-x ASA so my ASA would not support ASDM itself to provide the function of DC. When the ASA receives the response from the DNS server for the ACE hostname resolution, the answer has a Time to Live (TTL) associated with it. Anyways, it works, but it can cause unnecessarily long lookup times or, depending on how DNS is configured, sporadic success. inspect rtsp . class inspection_default. Configure this network object, FQDN object, and the ACE to allow the client with IP address 10. instagram. inspect sunrpc Jan 25, 2011 · URL filtering directly on the ASA using regex, should be used only sparsely when broad classifications can be applied, with limited regex patterns. 165. For instance some older PIX and ASA firmwares will drop by default as exampled here. com. DNS Server A responds with an answer of 2. 222. For some messages, you can automatically configure access Sep 28, 2010 · For transfers from another DNS server to yours (make sure this is correct, can be very dangerous) - permit tcp host [remote dns server] host [your dns servers public IP] eq 53. Check DNS. inspect Most routers and firewalls will allow you to force all DNS traffic over port 53 on the router, thus requiring everyone on the network to use the DNS settings defined on the router (in this case, Umbrella's DNS servers). host 8. inspect ftp. 1 and above ASA FirePOWER module €(ASA 5515-X, ASA 5525-X, ASA 5545-X, ASA 5555-X) running software version 6. I do not know if you have the ability to manage your endpoints where you can restrict network settings but that is also a reasonable alternative. For external people querying your DNS servers for dns lookups - permit udp any host [your dns server public IP] eq 53. Sep 16, 2010 · Here's the scenario: We have a mail server that needs to send out bulk emails to internal and external addresses. When you create an ACL statement for inbound traffic (lower to higher security level) then the destination IP address has to be: The translated address for any ASA version before 8. 0 0. Feb 13, 2024 · ASA has Botnet Traffic Filtering feature with a different design. I understand that the ASA cannot act as a DNS server, but can the "ip dns server" and "ip name-server x. I imagine that the static PAT rule might look like this: nat (inside,outside) source any destination any port 53 → destination 208. To keep the discussion focused, this post will look only at the Cisco ASA firewall, but many of the ideas are applicable to just about every device on the market. You must define a DNS condition in a DNS rule. Tunnel-all-DNS - Only DNS traffic to the DNS servers which are defined by the ASA is allowed. The IDFW gives a new level of control to ACLs. 67. This option slightly modifies URL filtering behavior and is applicable only when URL filtering is enabled and configured. I have a requirement that we need to allow outbound internet traffic only to specific domains like (Microsoft, Symantec) from a patching/updates point of view & Deny all other outbound traffic. Here is the example: access-list inside-acl permit udp any any eq 53. Then, from the client PC, try to access www. This is because your iPhone will fall back on unencrypted DNS traffic, which may be monitored by other devices on the same network. Aug 9, 2020 · @shon said in Filtering/Blocking & or AppID detection of DNS over HTTPS (DoH) or DNS over TLS (DoT) via Snort/Suricata:. Sep 21, 2013 · Hello everyone, i am having trouble with my outbound SMTP traffic. 1 (Core Router - Handles DHCP/DNS) 192. Task1 : How to check interfaces and security levels in ASA firewall 1. When you create a DNS policy, the ASA FirePOWER module populates it with a default Global DNS Do-Not-Block List rule, and a default Global DNS Block list rule. Mar 17, 2014 · Malware is malicious software that is installed on an unknowing host. This is pretty similar to the "Black Hole Routing" technique used by ISP's to block traffic from bad actors, and it worked really well in my ASA and blocked all traffic from any null0 routed prefixes from accessing the ASA itself or transiting the ASA toward any other hosts, so you may want to give it a try and see if it meets your requirements. com, and www. facebook. Here is what I have in my access list and access-group: ASA5505(config)# show run access-list Nov 2, 2020 · Blocking Traffic Using Security Intelligence IP Address Reputation. The Cisco ASA firewall 8. i also have three interfaces configured the inside, DMZ, and outside. The Enable reputation enforcement on DNS traffic option is enabled by default on the Advanced tab of each new access control policy. I am sure this is a common scenario in every environment. Sometimes, the mail server would need to send a lot of emails in one burst, so to speak, and I think ASA is blocking it. inspect h323 h225. Sep 7, 2010 · Some time ago we began having trouble with traffic back and forth between two of the sites -- it appeared that certain ports were being blocked through the VPN tunnel. match regex BLOCKED_DOMAIN_1 Nov 10, 2015 · DNS conditions in DNS rules allow you to control traffic if a DNS list, feed, or category contains the domain name requested by the client. 2 introduced something called Identity Firewall. (I’d do both UDP and TCP) We recommend disabling DNS packet inspection for traffic between the Virtual Appliance and Umbrella's DNS resolvers. Sep 30, 2019 · A DNS sinkhole is a DNS server that provides false information. Nov 1, 2012 · I am seeing requests for DNS updates being denied on my DNS servers. 8. 201. 16. 2 to access facebook. x (ASA 5505 - VLAN) I'm able to get onto the Internet withou • The maximum client DNS message length is automatically set to match the Resource Record. Nov 8, 2013 · access-list LAN-IN remark Block all other DNS traffic. Step 1. I have also disabled same-security traffic with the same result. Feb 18, 2009 · I could request that the helper addresses be removed, but my first thought was to simply block port 67 and 68 from passing through the ASA. 3. 1 is the IP of the ASA's inside interface, nat rule woul look smth like this: object network GOOGLE_DNS. So in the ASDM I crated 2 network objects and created a network group with the 2 DNS servers I want to use. access-list LAN-IN remark Other firewall rules. As a first line of defense against malicious Internet content, the ASA FirePOWER module includes the Security Intelligence feature, which allows you to immediately block connections based on the latest reputation intelligence, removing the need for a more resource-intensive, in-depth analysis. ASA cannot do deep packet inspection or inspection based on regular expression for HTTPS traffic, because in HTTPS, content of packet is encrypted (SSL Actually, the only way to block traffic in cisco ASA is to use the defence center with the SFR module in my case. 7 > terminal server Now yesterday i removed 10. 40. I have the following in my ASA: Oct 17, 2017 · I have two separate links terminates on two different ASA 5510 (F11 and F13). com" on my ASA. 0 100. Some vendors call these firewall rules, rule sets, or something similar. The preferred recommendation is to forward all DNS requests to of non-Umbrella IPs to go to the IP's listed below instead. Oct 21, 2010 · Assuming that you would like to allow only a few people web traffic, and block the rest web traffic, however, still allow outbound mail and dns request. I can see that inbound tcp streams are being built from dc1, but there is no outbound response in the logs from dc2. Explicit allow your DNS and block any any on 53. Jun 27, 2013 · I'm having problems with a domain controller (dc2) responding to DNS replication data from a remote dc (dc1). 4 > fileserver 10. When this option is Inspect the identified traffic by class !--- "URLBlockList"! policy-map type inspect dns preset_dns_map parameters message-length maximum 512 policy-map type inspect http http_inspection_policy parameters protocol-violation action drop-connection class AppHeaderClass drop-connection log match request method connect drop-connection log class Aug 1, 2021 · Hi, I have ASA5506 running version 9. Real time eventing just shows "Intrusion block". 2(4)25 Unrestricted (UR) license This is my current configuration: config t int e0 ip address dhcp setroute nameif outside no shut int e1 ip address 10. Instead of resolving FQDN configured in an ACLs, ASA sniffs DNS requests and responses and populates cache from DNS traffic. DNS Filtering: Block access to known VPN domains by configuring DNS filtering to prevent devices from resolving the IP addresses of VPN servers. 10. I'm trying to use FQDN that I configured in a network object in my ACL to allow a traffic to that FQDN but my ASA kept blocking the traffic, If I resolve the FQDN and use the IP addresses it resolves to it works fine, that tells me my ASA is not resolvin Nov 1, 2012 · I am seeing requests for DNS updates being denied on my DNS servers. See Blocking Botnet Traffic Manually. inspect sqlnet . The ASA will not scale being used in an enterprise with large regex matches and large volumes of HTTP traffic. parameters. They move through the tunnel (to the DNS servers that are defined on the ASA, for example) while others do not. google. This setting is Jul 27, 2019 · Blocking URL using Cisco ASA CLI. inspect rsh. Malware that attempts network activity such as sending private data (passwords, credit card numbers, key strokes, or proprietary data) can be detected by the Botnet Traffic Filter when the malware starts a connection to a known bad IP address. i tried to block facebook using this asa. When the domain name in a DNS reply matches a name in the dynamic database, the Botnet Traffic Filter adds the name and IP address to the DNS reverse lookup cache. Using tools such as packet captures and syslogs, the ASA can also be a useful troubleshooting tool in identifying asymmetric routing problems. Jul 10, 2016 · As I’m working on this, any ideas or thoughts might help. inspect ip-options. 100. inspect h323 h225 . 2 Another which is a Cisco Firewall, o Mar 11, 2019 · To permit communication between interfaces with equal security levels, or to allow traffic to enter and exit the same interface, use the same-security-traffic command in global configuration mode. 168. 0 is nat'ed to the outside interface public address. Oct 5, 2012 · Hi I've setup Cisco router's DNS server via "ip dns server" which in need for inside use. Edit: the issue is that icmp traffic is not statefull. the following command where used for blocking it regex domainlist1 "\\. Throttling or Rate Limiting. In my opinion, ONLY necessary traffic should go out, so “unwanted traffic” for me is EVERYTHING that is not required. Oct 11, 2010 · I need to be able to use the 'inside' IP address of an ASA 5510 (v8. message-length maximum client auto. local at the end which need resolved. 2. 0 nameif inside no shut exit global (outside) 1 inter nat (inside) 1 10. Thank you, Jun 1, 2011 · hi, we are having 5510 ASA. 6 and replaced it with a ne Aug 26, 2020 · Hi We have several site to site vpns on our new FTD devices i have noticed that if traffic (DNS) originates from the remote 3rd party side of the vpn it gets blocked, e. inspect dns preset_dns_map. 6(1) Device Manager Version 7. access-list LAN-IN deny udp any any eq 53. Block specific urls. 8 and 192. The request is sent to a loadbalanced pool of DNS servers. Regardless of whether you add a global or custom whitelist or blacklist to a DNS condition, the ASA FirePOWER module applies the configured rule action to the May 23, 2024 · Split DNS - The DNS queries which matches the domain names, are configured on the Cisco Adaptive Security Appliance (ASA). Mar 10, 2019 · There should not be any overhead on the ASA, also you can use the packet capture utility on the ASA to see if the traffic is indeed being blocked. All of Mar 19, 2024 · You can create rules to block VPN applications or protocols based on their behavior, such as tunneling encrypted traffic over a specific port. This traffic filtering takes place before any other policy-based inspection, analysis, or traffic handling. Nov 25, 2016 · Here are some basic ASA firewall troubleshooting tips for network traffic passing through the ASA. The Botnet Traffic Filter checks incoming and outgoing connections against a May 26, 2021 · DNS Filtering: Identify URL Reputation and Category During DNS Lookup . message-length maximum 512. The last sentence all depends upon what you mean by “unwanted traffic” going out. 2 but the client has an entry of 1. Although this disables the logging and protocol inspection on the ASA, it enhances security by allowing DNS encryption. Thank you, Jun 26, 2013 · ASA Allows any kind of source and destination NAT/PAT as long as it makes sense)). The mail server is located in the DMZ switch which then plugs into one of the interface in ASA. x) - ASA - Cisco 4500 - DNS server (192. The above ACL when inserted to the top of the existing ACL then you would now allow DNS traffic to your internal DNS servers and then block all other DNS Nov 10, 2017 · What happens is that FP is blocking mostly DNS traffic to public DNS servers, even the most legitimate requests like google. Each rule is fixed to the first position The ASA will use the internal DNS server (or any other DNS) to resolve the IP and put a “deny IP” entry in the inbound ACL applied on the “inside” interface. com " access-list TRAFFIC_TO_INSPECT_FOR_BLOCKED_DOMAINS extended permit tcp any any eq http . 0. Most firewall software will drop packets silently, so I'd check your DNS server to make sure you're properly blocking UDP/137 traffic. Jan 29, 2018 · It is this traffic that we are trying to filter when passing thru the ASA. In order to match DNS traffic using Security Intelligence, you must select a DNS policy for your Security Intelligence configuration. Historically some firewalls have been known to block the use of this extension. 2. Traffic on a Block list is dropped without further inspection. object network obj-10. Hope that helps. Sep 30, 2008 · For reliable file blocking, a dedicated appliance such as Ironport S Series or a module such as the CSC module for the ASA should be used. If you choose not to block malware traffic automatically, you can block traffic manually by configuring an access rule to deny traffic, or by using the shun command to block all traffic to and from a host. I'm using 1900 series. What do you observe? Take a look at the packet capture. You can use the commands for basic checks on ASA firewalls. Apr 18, 2013 · Hello Mahesh, If you want to block traffic to that IP from any interface, then you can apply it on the outside interface outbound direction: access-list name deny ip any host x. 323, etc" are and add inspect icmp. Having to analyze traffic and change addresses is going to tax your gear and is more complex overall. Can I block the requests at the ASA without interfering with legitimate traffic? I am thinking yes by allowing my ISP DNS servers then blocking all other traffic on port 53 but would like to verify. class-map type regex match-any CLASS_MAP_BLOCKED_DOMAIN_LIST . inspect ftp . Each rule is fixed to the first Aug 14, 2014 · Step 5 (Optional) Block traffic manually based on syslog message information. Jul 3, 2018 · DNS Bogon: Collection of domain names that do not allocate but resends the traffic, also known as Fake IPs. Source Networks: any Original Client Networks: 209. object network LAN Dec 5, 2012 · Whilst most of the IP over DNS tunnel tools use TXT records, this doesn't have to be the case and that the most likely way to identify (and therefore block) would be based on statistical analysis of DNS traffic, eg unusually large number of subdomain lookups, unusually large subdomain lengths, unusually high numbers of requests etc, which of Sep 25, 2012 · I inherited a Cisco ASA 5505 and am trying to piggy back the device off of an established Network. If I set my nslookup server to 8. x Aug 14, 2014 · How the ASA Uses the Dynamic Database. See Security Intelligence Lists and Feeds May 3, 2013 · match default-inspection-traffic!! policy-map type inspect dns preset_dns_map. When you create a DNS policy, the ASA FirePOWER module populates it with a default Global DNS Whitelist rule, and a default Global DNS Blacklis t rule. After much work we finally determined that the ASA was either blocking ports through the tunnel or somehow filtering packets. 50. It is not allowing me to do NS Lookups from any internal DNS Servers, or clients. Hey Everyone, The use case is I would like to identify (alert), and or block DoH and DoT traffic from leaving my network LAN => WAN my network if possible either through Snort or Suricata app identification. The system logs a Security Intelligence event for the traffic. When this option is Jan 1, 2011 · The ASA protects the network by blocking traffic flows unless it is able to inspect the entire (both sides) of the connection. Lina is the ASA code that FTD runs on, and the snort process is the network analysis of the packets that goes from security intelligence (SI) through the ACP inspection of the traffic by the Snort IPS rules. Set up a capture on the ASA outside interface to capture DNS traffic. 2 name-server 10. 6 > terminal server 10. 1 255. Mar 19, 2009 · boot system disk0:/asa804-k8. The ASA will keep that domain-to-ip mapping active until the TTL expires, at which time the ASA will re-resolve the IP address of the hostname. 200 1 Security Intelligence works by blocking traffic to or from IP addresses that have a known bad reputation. Get your ACL to work. Step 2. There is an extension to the RFC known as EDNS0, which implements the ability to extend DNS messages beyond 512 bytes on UDP transports. This would let you monitor what is being resolved, and make decisions on whether to block particular domains at the DNS server. When this option is Jun 1, 2011 · hi, we are having 5510 ASA. g servers on the remote end need to hit our DC's so the servers are initiating the request, I thought all traffic would be allowed Jul 22, 2012 · match default-inspection-traffic!! policy-map type inspect dns preset_dns_map. Oct 22, 2012 · One gateway box I worked with interpreted the outbound DNS traffic as a UDP storm, and was blocking it. com, www. twitter. May 3, 2019 · Also, it is very difficult to whitelist all good traffic from the inside-out as opposed to blocking unwanted traffic from the inside-out. 2) as the recognized DNS server configured in TCP/IP settings on internal workstations. Mar 4, 2025 · The ASA uses Botnet Traffic Filter snooping instead of the regular DNS lookup to resolve static blacklist domain names in the following circumstances: The ASA DNS server is unavailable. Have you configured the Default Route towards the ISP (assume default gateway is 100. Mar 9, 2015 · The easiest way to figure out why your ASA drops traffic: If it's a routed ASA firewall, use packet-tracer; Both routed and transparent ASA firewalls can use capture [NAME] asp-drop; Using packet-tracer (only on routed ASA firewalls): ASA FirePOWER modules (ASA 5506X/5506H-X/5506W-X, €ASA 5508-X, ASA 5516-X ) running software version 5. x" commands be used to forward DNS Feb 15, 2022 · By default an iPhone does not use encrypted DNS; you (or someone) must have set it up to use encrypted DNS, or you installed a VPN app. But this is a question best asked of the Cisco folks, as this won't be the first DNS server located behind a Cisco widget, and as OS X Server is running a bog-standard ISC BIND DNS server. access-list LAN-IN deny tcp any any eq 53. In order for the firewall to block a domain name it has to be able to resolve domain names. 8(1). below is the config that i applied . May 26, 2021 · Rules in a DNS policy are numbered, starting at 1. What are trying to accomplish? Assuming that you're trying to redirect all the client's DNS requests to the 8. Instead of returning a “No such name” DNS response to DNS queries on domains you’re blocking, it returns a fake IP address. Create an Access Control List in such a way that you block the specified port traffic. access-list inside-acl permit tcp host any eq 25. This is a completely different story, but at some point the feature was deprecated. inspect netbios. Using Block or Do Not Block lists, or monitoring traffic based on a DNS list or feed, also requires that you: Configure DNS Security Intelligence lists and feeds. When this option is May 25, 2022 · DNS Policy. bin ftp mode passive clock timezone EST -5 clock summer-time EDT recurring dns domain-lookup inside dns domain-lookup outside dns domain-lookup home dns server-group DefaultDNS name-server XX001 name-server XX002 domain-name example. inspect h323 ras. 1 traffic will be incorrectly (depending on the ACL action Mar 3, 2009 · Step 5 (Optional) Block traffic manually based on syslog message information. The ASA then queries DNS for xyz. The ASA FirePOWER module matches traffic to DNS rules in top-down order by ascending rule number. Mar 3, 2021 · Hi there, Dear Members, i am using Cisco ASA 5520 firewall in my company, i am using the ACL to block some specific traffic for some clients, which is working fine, now i want to block specific websites through ASDm, can anyone help me how can i do that in Cisco ASDM, i will be really great full t Aug 7, 2023 · DNS Filtering: Identify URL Reputation and Category During DNS Lookup . Let's say 10. 6(1) And the sfr Mod SSM Application Name Status SSM Application Version ---- Its a default behavior. . The real address for ASA 8. The access-list is always checked before NAT translation. Navigate to Objects >> Object Management >> Sinkhole >> Add Sinkhole and create the fake IP address information. inspect rsh . You can now configured ACLs to block domain names. com" access-list inside_mpc extended permit tcp any any eq www access-list inside_mpc extended permit tcp any any eq 8080 access-list inside_mpc Mar 3, 2021 · Hi there, Dear Members, i am using Cisco ASA 5520 firewall in my company, i am using the ACL to block some specific traffic for some clients, which is working fine, now i want to block specific websites through ASDm, can anyone help me how can i do that in Cisco ASDM, i will be really great full t Aug 7, 2023 · DNS Filtering: Identify URL Reputation and Category During DNS Lookup . interface GigabitEthernet0 nameif outside security-level 0 Feb 15, 2011 · Complete these steps in order to block the ports, which usually apply to traffic that originates from the inside (higher security zone) to the DMZ (lower security zone) or the DMZ to the outside. my incoming email pass with no problemes but my outgoing onse do not they get stuck in my DMZ with the follwing message No route Jan 17, 2017 · Hi guys, need a clue about I have an asa 5506-X that is running the next version Cisco Adaptive Security Appliance Software Version 9. Jan 19, 2015 · Create a rule that’s applied to your outside interface that allows all outbound DNS traffic from the IP addresses of your DNS server to whichever DNS server you want to talk to. x) For some reason, almost all of a sudden, the udp on port 53 seems blocked at the ASA. Syntax: same-security-traffic permit {inter-interface | intra-interface} Sep 7, 2010 · ASA can not act as a DNS server or proxy DNS or dns caching only server. com from a browser. 3 and newer. Simply stated, I want to take all outgoing DNS requests from my network and force them to go to a specific IP address. Configure the ASA to resolve DNS. x. The ASA also monitors the message exchange to ensure that the ID of the DNS reply matches the ID of the DNS query. however now if I do portscan from outside it shows port 53 opened. So the outgoing packet is permitted, but the ASA sees no as Now i am trying to block "youtube. Encrypted DNS is a new service that doesn’t have an accepted standard yet, and many networks won’t support it. If I am on the internal network, breaks. Ask Question CST -6 clock summer-time CDT recurring dns domain-lookup inside dns Jun 13, 2011 · I have followed the instructions listed here (thread1598-1597009) but it still isn't blocking DNS traffic when I manually set a workstation behind the ASA5505 to 4. It is not required, but if it exists will be added to the DNS suffix search list. ASA is connected through a l2l VPN, inside subnet of 192. See the “Blocking Botnet Traffic Manually” section. Apr 25, 2019 · Monitored traffic is subject to further evaluation by remaining rules on the DNS Block list. regex BLOCKED_DOMAIN_1 "youtube. Let’s take a look at some examples how we can use access-lists. DNS Bots: Collection of domain names that actively participate as part of a botnet, and are controlled by a known botnet controller. my ASA is pointing to an internal DNS server that is able to resolve the FQDN. inspect h323 ras . 1 Action: Block To control traffic by network or geographical location: Procedure May 17, 2018 · Understand that there are 2 main engines in the FTD unified software image: Lina and Snort. policy-map global_policy. Aug 8, 2023 · DNS Filtering: Identify URL Reputation and Category During DNS Lookup . Look for the group-policy where all the other "inspect sip, inspect h. Nov 14, 2024 · Configure the DNS setup on the ASA as shown here: Configure 4 FQDN objects for www. If you need to allow traffic through the firewall then it would be best to post a seperate discussion in the Firewalling forum. Mar 15, 2017 · I am trying to limit all of my DNS queries from my inside network to only go to certain DNS Servers on the internet and deny any other DNS request. 1. facebook\\. May 12, 2022 · Sometimes your iPhone will display a warning under Settings > Wi-Fi which claims that "This network is blocking encrypted DNS traffic" and states that the sites you visit may not be entirely private. Here is the basic layout: 192. ASA 5505 Blocking traffic. inspect esmtp . 222 port 53 In other words, if you see a UDP or TCP packet with a DNS request Mar 25, 2017 · This 5505 is blocking traffic both in and out. Here's what works : ALL TCP, including 3389, 53 TCP, bidirectional ping. The user has local domain names with . com, and to make matters worse the blocked traffic is random and there is no way to determine why. The VPN (cisco VPN) user (172. In general, a network interface in Windows should have a connection-specific DNS suffix. i have 5510 ASA with IPS module. Downloaded the latest defence center (firepower management center) from the cisco website. The ASA uses the dynamic database as follows: 1. 2 host May 26, 2021 · Rule 3: Blocks proxied traffic from the same IP address if it uses any other proxy server. Nov 26, 2011 · Block URLs using FQDN objects. Oct 27, 2014 · I have an ASA 5515 as my internet firewall. Note that you could create access control rules that perform a similar function to Security Intelligence Likely not an issue with the ASA blocking per se -- but a DNS 101 issue. A connection is initiated during the 1-minute waiting period before the ASA sends the regular DNS request. 3. Jun 16, 2021 · If you choose not to block malware traffic automatically (see Enable Traffic Classification and Actions for the Botnet Traffic Filter), you can block traffic manually by configuring an access rule to deny traffic, or by using the shun command to block all traffic to and from a host. 4. access-list inside-acl permit tcp host any eq 80 The ASA DNS entry then expires 30 secs later. 0 icmp Jan 17, 2024 · Ensure that the DNS server is configured correctly on the ASA: ciscoasa# show run dns dns domain-lookup outside dns server-group DefaultDNS name-server 10. Jun 16, 2011 · Increase the lifetime for short-lived DNS records. 0 and above The information in this document was created from the devices in a specific lab environment. com same-security-traffic permit intra-interface Apr 3, 2015 · The network is as follows: Two Default Gateways exist on the network - one which provides connectivity to the an MPLS with several subnets. DNS policy are numbered, starting at 1. Let’s now see the required configuration on the ASA to achieve the above scenario: domain-name mycompany. Aug 30, 2015 · Using Cisco PIX 515E firewall Version 7. com again. com" access-list inside_mpc extended permit tcp any any eq www access-list inside_mpc extended permit tcp any any eq 8080 access-list inside_mpc Aug 1, 2021 · I'm trying to use FQDN that I configured in a network object in my ACL to allow a traffic to that FQDN but my ASA kept blocking the traffic, If I resolve the FQDN and use the IP addresses it resolves to it works fine, that tells me my ASA is not resolving the FQDN. Oct 27, 2012 · Hi guys/ladies I have a cisco ASA5505, it runs a wide site to site VPN network and has 4 servers connected to it 10. 0 255. 15. If the traffic does not match a DNS Block list rule, it is inspected with access control rules. 9 (ASA 5505 - Piggy backing off of Network) 192. If you choose not to block malware traffic automatically, you can block traffic manually by configuring an access list to deny traffic, or by using the shun command to block all traffic to and from a host. What i did is: 1. They had roots on the internal DNS server set to DNS servers of the primary ISP, so, during failover testing, recursive DNS would egress via the failover ISP and take this unecessarily lengthy path. Use a layer 7 / DPI firewall, or handle DNS resolution internally and filter at the DNS server. As the ASA still has a DNS cache entry of 2. Ok, now we know that an internal host is sending UDP/137 traffic to your DNS server and the DNS server is sending an ICMP port unreachable back to let the client know it's not listening. Nov 1, 2016 · The first line of defense in a network is the access control list (ACL) on the edge firewall. 8 (google DNS), I can resolve public DNS names. nyorf cju fmbvr ajnmekl mviiwvicg xpsmvpr fyouzy vywjwq oont okjjeh tctl knub iyt ucme ewnintko