Cisco Firewall :: ASA 8.2.4(4) Seems To Be Dropping Valid TCP SYN Packets?
Feb 28, 2012
We have a setup with a MS-TMG - ASA (8.2.4(4) in routing mode) - (internal) Router - FWSM - Router - Exchange with NLB. We have now the problem that IMAPS is not really working through this setup. It works from internal (without ASA and TMG inbetween), but not reliably through the internet. There is a rule on the ASA which permits the ports from the TMG to the Exchange NLB address.We opened a case with Microsoft and they told us that not all tcp-syn packets are received by the Exchange server which were sent by the TMG.Thus I sniffed on the ASA with a packet capture and indeed, a lot of syn packets were on the interface to the TMG, but not anymore on the interface to the internal router.This ASA also filters all other internet<->company traffic, so there's a lot of stuff running.
Maybe it's dropped in the ASP, or is the capture maybe not valid?Here the show asp drop:
ASA01-Internet# sh asp drop
Frame drop: Invalid TCP Length (invalid-tcp-hdr-length) 1 Reverse-path verify failed (rpf-violated) 319 Flow is denied by configured rule (acl-drop) 477077 First TCP packet not SYN (tcp-not-syn) 10212 TCP data send after FIN (tcp-data-past-fin) 41 TCP failed 3 way handshake (tcp-3whs-failed) 824 TCP RST/FIN out of order (tcp-rstfin-ooo) 1419 TCP SEQ in SYN/SYNACK invalid (tcp-seq-syn-diff) 6 TCP SYNACK on established conn (tcp-synack-ooo) 1 TCP packet SEQ past window (tcp-seq-past-win) 821 TCP invalid ACK
I am having an issue where the ASA is dropping packets on the vlan interfaces. I have it as a dedicated router/firewall for a 100mb connection .
Vlan1 is the internal networkVlan2 is the network to cable modem
Eth 0/1 is connected to a 2960G switch with hard coded 100mb Full Duplex at each end, this is the inside interface. Eth 0/0 is the connection to the cable modem, this is the outside interface, set at auto at both ends.
Im getting on the vlans eg. 51253 packets dropped however network traffic isnt impacted and everything runs fine, as well as 46532 switch ingress policy drops.
ciscoasa# sh int vlan1Interface Vlan1 "inside", is up, line protocol is up Hardware is EtherSVI, BW 100 Mbps, DLY 100 usec MAC address 70ca.9b36.ab80, MTU 1500 IP address 10.x.x.x, subnet mask 255.255.255.0 Traffic Statistics for "inside": 43250588
I have a Cisco 871 router that used to have Access list based security. now I am trying the ZBFW for the first time. I thought I had a pretty good program until I found all my traffic was getting dropped. This is my first stab at ZBFWs and I am a bit confused esp with the default class part.
The router is for my house and thus also has to have priority for gaming. I will add the gaming and voice QOS once I get it working,
Guest VLAN has access to 2 IP's in Data for printing. Cisco871#sh run
Current configuration : 8005 bytes ! version 12.4 no service pad
I am attempting to FTP to a remote site through a IPSEC tunnel.When I am transfering large files the ASA5540 is showing syslog errors stating "connection timeout". What I think is happening is after about 1 hour the firewall is closing the connection control port for the FTP session and neither end is notified so eventually the transfer is stopped.What do I need to modify in the FW to accommodate these larger files?
I have 2 ASA 5510 firewalls at 2 different sites. Both running on version 8.0.4. Users are using an Instant Messaging type of application provided by a local telco here which is able to send and receive SMS using SIP (from the packet capture that I've done).
When users use the IM in site A, they are able to send and receive text messages via the IM from behind the firewall. However, when the users are in site B, users are able to send out text messages but not able to receive them.
I noticed that when I remove "inspect sip" from site-B's global policy map, users from site-B can successfully receive text messages. I have confirmed that it is the firewall that drops the packets as I have captured the inside and outside interfaces of site-B's ASA and I can see the incoming sip "request: MESSAGE" packet on the outside interface but I do not see the packet exiting the inside interface.
I have cross check both firewall configurations, and I do not see anything suspicious commands relating to sip that might cause this issue. Is there any command to troubleshoot why the sip inspection is dropping the sip packets on site-B?
I have ASA 5510 with 8.4 connected to ISG 1000, when traffic is passing the VPN tunnel is working fine, when the traffic stops, ASA will drop the packet but the VPN tunnel on ISG still up .When new traffic started from ISG side, it will drop, as the tunnel is not up on ASA side.
We have a cisco 800 series router between the internal network and the WAN. the problem is we are unable to receive some of our mail due to dropped packets by our router. the conversation between the two servers stops at the point were our server responds with the command 250 2.1.5 email@example.com | 354 Start mail input; end with . i was able to trace the packet, using Packet Export, on the internal interface but not on the external interface. Also i have noticed that the external interface has about 160,000 unknown protocol drops while the internal interface has 0.
Is there anyway to find out way the external interface is dropping the packets.
We have a customer who we sent to Cisco to replace some aging Dell switches. They purchased 5 SG300-52’s for 2 different networks. Their production LAN has 2 “live” switches and 1 spare. The 2nd, a development LAN has 1 switch and 1 spare. Their primary production SG300-52 has GE1-8 VLAN’d off as VLAN2 for public IPs. The untrusted (WAN) interfaces of 2 x ASA-5510’s, 1 x ASA-5505, and 2 x RV082 v2’s are connected to GE2-6. GE1 is the uplink to the co-location center’s Cisco switches. GE7 & 8 are spare ports. Each SG and device port is hard coded for 100/Full.
One of the ASA-5510’s and the ASA-5505 maintain a site-to-site VPN (the development LAN used to be in a different facility hence the VPN). Recently the developers have stated the performance is horrible. I noticed ping traffic loss from PCs on the dev side to servers on the production side in the order of 20-30%. I assumed it was a VPN issue so I opened a ticket with Enterprise TAC (all the ASAs and the SGs have either SmartNet or extended support contracts). TAC determined the problem happened even if you ping from inside the ASA to the untrusted side of the other ASA thus eliminating the VPN as the culprit.
The 2nd ASA-5510 has the AIP module and was not even live until this weekend. Turning it up and giving it a basic config returned the same results. #ping x.x.x.x repeat 100 will drop 20-40 packets. I have no security enabled on the SGs and even tried using the spare SG300-52 this weekend in place of their primary with the same result. I’m to the point of returning one of the Dell switches to production, but this cannot be a good sign. I’m also a bit frustrated that I’ve yet to figure out how to get Cisco Enterprise to speak with Cisco Small Business on this. The customer has over $10k invested in Cisco equipment and Cisco isn’t jumping in to figure this out.
The latest rep wants a packet capture from the SG300’s VLAN2 but there are no PCs there to do this with and the manual doesn’t even talk about doing this. How we can do this as well as get the 2 divisions working together to fix this? BTW, the RV082’s exhibit the SAME exact problem. I can ping from ANY device on VLAN2 to any other device and drop packets. Copying a simple 1MB file over the VPN can take minutes where it should take 1 second. I can reproduce this for 24/7.
It appears we might have an issue with our RV082 (v4.2.1.02) dropping packets during the teardown of many TCP conversations. I have attached two packet captures of what I believe is the same conversation. One is from outside the router (Wireshark using an Ethernet Tap) and the other is from the client inside the router (SLES11SP2 running TCPDump). These are both very small captures 9 packets and 18 packets and I'm hoping it will identify the problem.
It appears that the RV082 is prematurely closing the natted port used to communicate with the host outside the network. The host sends a FIN, ACK packet, to which the client responds with an ACK, However, when the client then sends his FIN,ACK sequence, it never makes it outside the router. The client sends a total of 9 FIN,ACKs trying to contact the outside server, but none of those appear to make it through the router.
Is the router slamming the door prematurely? (I've been fighting with this problem for 3 weeks now!)
We have a Cisco ASA and recently purchased a cisco small business srp527 router. It is connected to our ADSL2 connection and is working fine. I have configured the device with an ipsec tunnel using an ike profile and the tunnel is created successfully with packets traversing the tunnel. However packets are being dropped intermittently, with no cause. The link is currently not being utilised, there is no load on the network however when I ping Google and any address subject to the rules of the tunnel i notice that a single packet is dropped every now and then.
I seem to be having an issue where certain very packets are being dropped/lost by my office router. The reproducible situation is, when I attempt a DNS zone transfer from my linux bind DNS server (A.A.A.A) to any server on my network behind NAT (Y.Y.Y.Y) the first packet (Seq 1) of the response is lost. The client making the query asks for first packet (Seq 1) to be resent, and the DNS server attempts to resend it repeatedly, but those are lost too.
We have a customer who uses about 20 x c2960's switches for access layer and 2 x c3560e for distribution layer. C2960's uses C2960-LANLITEK9-M , Version 12.2(58)SE1. Everything was working fine. Now we got information, that sometimes there are problems with connectivity. Customer tries to reach internet.
SW11#sh int fa0/18 FastEthernet0/18 is up, line protocol is up (connected) Hardware is Fast Ethernet, address is e8ba.806a.4412 (bia e8ba.806a.4412)
I am trying to find a solution using modular QOS when there is congestion in circuit we drop packets with WRED which are marked with a DSCP value of say AF21. I can drop those traffic completely in case of congestion. I was thinking to allocate 100% bandiwth to rest of the traffic.
I bought a DIR-655 a less than a year ago on amazon, and it was working great up until about 4 weeks ago. Ive noticed that it has been dropping alot of packets while I am gaming on my computer. I would run about 95-98 ping usually and now it jitters every 5-10 mins or so from 95-98 to up to 500. It is really troublesome during games and I dont know what to do. Ive tried disabling QoS and still nothing. I run on wireless G and N with auto 20/40 mhz. Standard WPA(personal) and it was running absolutely great until now. I know its the wireless because I have hardwired it into my laptop, both from the router and just the modem itself with no problems whatsoever. I dont know what to do about it.
I have a ACE module A2(3.5) installed, I am having a connectivity problem between two servers in my network. I have captured some traffic on different points in my network and from capture it seems like the problem is with this ACE module or somehow it is closing the connection.
I recently installed DHCP snooping on a 3750v2 switch (Version 12.2(55)SE4) and configured the uplink(Po2) as a trusted port. The problem is that clients cannot receive an IP address. When I disable DHCP snooping it is working properly. DHCP snooping is configured correctly but I don't have an idea how to resolve it. [code]I tested the solution on the same kind of hardware switch and firmware and it worked out fine. What is causing the clients not to receive an IP address from the DHCP server?
We have a remote site that is using 3750X switches as layer 2 switches back to our home site. The uplink port is showing dropped packets but the utilization on the link is never about 10%. We have a 100Mb circuit to this site. Our speed tests and iperf tests are not showing any issues that we can see. However the port is still droping packets. It is not dropping at a high rate but they are dropping.
We are testing a new 1Gbps WAN circuit between 2 sites. We have cisco 3750 and 4507 on each end. Every time we run extended ping sweep ranging from 36 to 18024 bytes the packets are being dropped randomly once the size goes above 1500 bytes. Our ISP claims Demark to Demark test are clean and they don't want to acknowledge the problem, they blame our switches. To prove the problem is not on our end we've put different switches at each end, still facing the same issue. Ping success rate is around 98 to 99 percent.
I am trying to use my WRT120n as access device for an IP Centrex service using SIP protocol. My SIP phone is located right behind the router.My problem is sometimes the router is dropping incoming calls because signalling packets are fragmented at IP level. So I cannot receive those calls.Is there a way to enable the router to accept these packets?
We have a Cisco ASA 5510 with a CSC SSM 20 module installed. As of this morning a valid site (Public School System) is being blocked at my site. It says the site is of High risk. I have tried entering the site in the block list exceptions but it still comes up as a high risk site.
We have a Cisco ASA 5510 with a CSC SSM 20 module installed. As of this morning a valid site (Public School System) is being blocked at my site. It says the site is of High risk. I have tried entering the site in the block list exceptions but it still comes up as a high risk site...
I do not have a valid SSL Certificate on my firewall but I want to use SSLVPN.
If I connect to the IP adress and the SSLVPN Portal I can choose the sslclient launcher but after that I get a error that I need a internet explorer 64bit or that the active I was blocked because of a unsecure publisher.
I am trying to configure my ASA 5545 firewall in area 0 but when I do so, the neighbor relationship never establishes. A debug on OSPF gives only one response: [code] Why the ASA is ignoring the input packets?
I happen to noticed the FWSM was dropping packets at about 387 packets every 5 minutes. My outside FWSM is WAN facing and has a 1gig link (35% utilized) my inside facing has about 100 downstream switches to the closets. I do not see my 6509's back plane is being over utilized and my understanding of the FWSM show be go for 5 gig so it isn't oversubscribe. Why i am seeing packets dropped?
We've had this firewall in place for years, and there haven't been changes to it in the past few months. Last week, however, we started having problems accessing one of our networks through the PIX, and after working with Microsoft, we determined it was an MTU issue. The maximum sized packet to the PIX and through the PIX is 1020 bytes, and it doesn't matter if the packets are sourced from a server or the PIX itself. From the server, we can ping 1500 byte packets to the core switch with no issues. All interfaces are set for 1500 byte.
Our Cisco ASA 5510 running 8.4(4)1 just started dropping packets and our AnyConnect clients are seeing horrible performance. The system is extremely slow compared to just a couple days ago.Nothing has changed on the system. I can post the configs if needed.
firewall# sho int Interface Ethernet0/0 "outside", is up, line protocol is up Hardware is i82546GB rev03, BW 1000 Mbps, DLY 10 usec Full-Duplex(Full-duplex), 1000 Mbps(1000 Mbps) Input flow control is unsupported, output flow control is off Description: == WAN Interface ==
I have done a "sho vpn-sessiondb detail svc" and I can see the dropped packets of the individual users, but cannot see why the packets are still dropping.how I can correct this and restore speeds?
We have an ASA5520 running ver 7.0(8), nat-control is disabled. On the "outside" interface we have a closed network which is publicly addressed i.e. no access to Internet. We also have two Vlan interfaces on a trunk connection i.e. "inside" interface (Vlan7) and "dmz" interface (Vlan802). Traffic from the "outside" to "inside" is statically NAT'd such that the public IP is translated to a private IP when accessing the "inside" interface. However, our OSS servers on the "dmz" interface need to be able to receive packets from the public IP addresses on the "outside" . All is okay with the outside to inside traffic and traffic initiated from the OSS servers on the "dmz" to the outside works okay (snmp gets etc) i.e. the servers receive reply packets from the public addresses of the outside devices.
However, traffic that originates on the "outside" interface (snmp traps etc) which is destined for the "dmz" is actually being routed to the "inside" interface and therefore the public source address is being NAT'd by the static NAT command. The access-list "in_on_outside" has relevant entries to allow connectivity from outside to dmz, we have tried a static nat command (outside, dmz) to maintain the public addressing but this made no difference and also a nat exempt. With ########nat-control disabled - do I still need a translation or NAT exempt for the "outside" <> "dmz" traffic flow, if so how should this look ?
My SIP provider is not convinced that my ASA and Edge Router is not altering the SIP packets. On the ASA I've removed the inspect SIP, and H323, what else needs to be done to make the firewall not mess with the SIP Traffic.