Internet Protocol Security

Internet Protocol Security (IPsec) is a protocol suite for secure Internet Protocol (IP) communications by authenticating and encrypting each IP packet of a communication session. IPsec includes protocols for establishing mutual authentication between agents at the beginning of the session and negotiation of cryptographic keys to be used during the session. IPsec can be used in protecting data flows between a pair of hosts (host-to-host), between a pair of security gateways (network-to-network), or between a security gateway and a host (network-to-host). IPsec is an end-to-end security scheme operating in the Internet Layer of the Internet Protocol Suite.

Share tech news, updates, or what's on your mind.

Sign up to Post

There is an IPSEC tunnel from a SRX240H2 to a Sophos UTM 9.

The tunnel is up most of the time but goes ocassionally down. And I wonder if the following could be related to the problem.

When the Sophos appliance sends this (from capture on the SRX):

Frame 10273: 310 bytes on wire (2480 bits), 310 bytes captured (2480 bits)
Juniper Ethernet
Ethernet II, Src: Cisco_xx.xx.xx (30:e4:db:xx.xx.xx), Dst: Netscreen_xx.xx.xx (00:10:db:xx.xx.xx)
Internet Protocol Version 4, Src:, Dst:
    0100 .... = Version: 4
    .... 0101 = Header Length: 20 bytes (5)
    Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
        0000 00.. = Differentiated Services Codepoint: Default (0)
        .... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    Total Length: 284
    Identification: 0xffe2 (65506)
    Flags: 0x02 (Don't Fragment)
        0... .... = Reserved bit: Not set
        .1.. .... = Don't fragment: Set
        ..0. .... = More fragments: Not set
    Fragment offset: 0
    Time to live: 57
    Protocol: UDP (17)
    Header checksum: 0x15b1 [validation disabled]
    [Header checksum status: Unverified]
    [Source GeoIP: Unknown]
    [Destination GeoIP: Unknown]
User Datagram Protocol, Src Port: 500, Dst Port: 500
Internet Security Association and Key Management Protocol
    Initiator SPI: 91ee52a313c081d6
    Responder SPI: 0000000000000000
    Next payload:…
On Demand Webinar: Networking for the Cloud Era
On Demand Webinar: Networking for the Cloud Era

Ready to improve network connectivity? Watch this webinar to learn how SD-WANs and a one-click instant connect tool can boost provisions, deployment, and management of your cloud connection.

Hi Sir,

Would like to ask for your help about the problem listed below,

[Tunnel Authorize Fail] ignoring Delete SA payload: PROTO_IPSEC_ESP SA(0xccb797a8) not found (maybe expired)

Hoping that you can help me resolve this matter.

Thank you in advance.
Hi again everyone -

So sorry to be a pest. Now that I have my ASA 5505 up and running with successful Internet access by devices on my LAN, I can't seem to get my DMZ to gain internet access. Nor can I get a simple IPSec site-to-site VPN to work.  This is really frustrating as the ASA on the other side already participates in another separate site-to-site VPN (setup by me) which works just fine.

I have looked at NAT rules and access rules and can't seem to find the difference. The only thing I did differently on this VPN was try Diffe-Hellman Group 1 as group 2 settings didn't work.

Below is the sanitized config of the ASA that has a working DMZ and a working VPN as well as the non-working VPN.  I have replaced my static public IP with xx.xx.xx.xx and the peer IPs in the VPNs are vv.vv.vv.vv for the one that works and for the one that doesn't work.

I will return to this post momentarily and add a comment with the running configuration of the ASA at the other site.

Thanks in advance for any help.

Result of the command: "sh run"

: Saved
ASA Version 8.2(1)
hostname ciscoasa
enable password /zzzzzzzzz encrypted
passwd zzzzzzz.zzzz encrypted
name dmz_outside
interface Vlan1
 nameif inside
 security-level 100
 ip address
interface Vlan2
 nameif outside
 security-level 0
 ip address xx.xx.xx.xx
interface Vlan3
 no forward interface Vlan1
 nameif dmz
I would like to understand the difference of persistent connection and keep alive. Is it only applicable to HTTP protocol? Thanks!
I freeze my credit report from 3 beaurues. Equifax, Transunion, Experian. I did that because some people knows my social and date of birth and I don't want they knows my new address. My question is what other agencies i can use to freeze my credit history?

Trying to create a Site to Site between our TZ215 and Azure:
VNET1 - Address Space     =
               Subnet  range      =

GatewaySubnet                  =

Virtual Net Gateway           = VPN
                                               = Policy-based
                                               = VNET1
                                               = VNET1GWIP  (created Public IP)

Local Net Gateway             = RP_OFFICE
                                              = Public IP address of SonicWALL
                                              = (LAN network on SonicWALL)

Connection                          = Site-to-Site (IPsec)
                                               = Virtual Net Gateway
                                               = RP_OFFICE
                                               = Shared key that matches what's configured in the SonicWALL

 General Tab                         = Site to Site, IKE using Preshared , IPsec Primary = Public IP of Azure, IPsec Secondary =, Local & 
                                                   Peer IKE ID = IPv4 address
Network Tab                         = LAN Subnets, Azure LAN network
Proposals Tab                       = Main Mode, Group 2, AES-256, SHA1, 28800, ESP, AES-256, SHA1, 3600
Seeing the following in the SonicWALL log:
I am looking into DMVPN issue. My tunnel keeps dropping, isakmp and ipsec is OK. If I shutdown my dmvpn tunnel interface and bring it back up, it all comes back up. Any ideas?

- I have 300 some sites with literally identical tunnel set up and config, none are doing this.
- all interfaces are UP and UP. Including tunnel int, outside and inside int's.
i have establish a vpn server in windows server 2012 R2 adn its works fine but when i try to connect with the 2nd server (The DATA Server) it shows nothing. please let me know that how i can connect the server using vpn connection.


Asad Rehman
We have issues while setting up client VPN on TP-LINK TL-ER6120 and TL-ER6020 routers. Even when it is connected, we are unable to ping the inside hosts.
Ransomware Attacks Keeping You Up at Night?
Ransomware Attacks Keeping You Up at Night?

Will your organization be ransomware's next victim?  The good news is that these attacks are predicable and therefore preventable. Learn more about how you can  stop a ransomware attacks before encryption takes place with our Ransomware Prevention Kit!

How can I block a computer from accessing the internet completely. but leave open remote desktop connection so the user can only use the internet when remoted in the their work computer via remote desktop.
blocking IE will not be enough since the computer has other browsers.
Its on window 10
What is the difference between  SSL vs IPsec VPN? Both needs tunnelng?
FCCInfographic-SocialMedia-Sina-OS.pngThe results of the net neutrality Day of Action are in! Thank you to everyone in our tech community who participated by sending comments to the FCC, emails to Congress, and called Congress. Check out the days total results reported in our article update.
Skyport2-SocialMedia-LinkedInV2.pngDid you miss our co-branded webinar with Skyport Systems yesterday? Check out the recorded webinar available on-site to learn how to secure your Active Directory against security threats.
So I've been tasked with creating an IPSec VPN using a Cisco RV325. I've followed through several guides to get this setup and as it currently stands, I've managed to create the tunnel, connect and authenticate to the VPN successfully using the Shrewsoft VPN Client. However, once connected with either the IPSec VPN or the EasyVPN, I am able to ping the internal address of the router, but unable to ping any other device on the remote LAN. I've made sure firewalls are turned off for testing purposes just to ensure the packets aren't being blocked. I've also tried RDP connections to devices with no joy.

Interestingly, when I tried using the PPTP VPN through the RV325 (using windows 'connect to a network') I'm able to ping everything and remote access servers etc.

I've noticed that the RV325 will give you a virtual IP address range (which the VPN client is picking up) although it seems like there's no kind of address translation or routing to the subnet I need to get to. My remote LAN uses 172.16.8.x/24, the virtual addresses use 172.16.9.x/24.

Please let me know if any log files, config files or screenshots of anything would be of any troubleshooting help and I'll get them posted. Any ideas welcome!

Many thanks in advanced,
Hey guys,

I´m troubleshooting very interesting issue...we have a branch connected over IPsec (setup on Mikrotik)...everything works pretty much fine but network drivers...when users wants to open it it takes very long time to open it approx 5 mins...if they connect over VPN everything is fine. Any ideas? We use 3des encryption for IPsec

Thank you very much!!


Hi All,
We have a Draytek 2960 setup with a teleworker dial-in connection using L2tp over IPSEC and it works perfectly for all users apart from those using Hp Elitebooks! The connection always fails with an Error 809 even though we can connect with the same details using another laptop from the same remote office.
We've even installed the draytek vpn client but that fails with an unknown error. I have switched off the antivirus and the firewall and this doesnt help.
Has anyone got any ideas?
saveNetNeutrality_NativeAd.pngThe internet-wide Day of Action for all user's rights to net neutrality is July 12th! Take a stand by signing the petition here or leaving a comment with the FCC here on why you support Title II. (Click the "+Express" link to leave your comment.)
Hello Experts,

We have a web server that is suddenly not sending out e-mails.  I did not do this set up, but here is what I know:

Event IDs:

10016 Distributed Comm has been present since 5/8
No usable TLS server certificate for SMTP virtual server instance '1' could be found. TLS will be disabled for this virtual-server
4006 SMTPSVC SMTP that started on 7/3


This server is a cloud server connected to our Active Directory through a IPSec VPN tunnel.  It has two network adapters, one for our internal network, one public.  Recently the hosting company looks like changed the nic settings and connection to our AD was halted because of it.  I restored it as of yesterday and Group Policy and authentication are working successfully but now these e-mails are not going out.  The developer is saying it's because of AD but I have done all checks and the server is connected not sure if that is accurate?  

I checked IIS and SMTP and it's SMTP settings are set to go out on port 25, anonymous access, I did a DNS check under advanced delivery and it was successful,  under the outbound security tab it is set to go to our 365 support e-mail with those credentials under basic - nothing under windows authentication and TLS is checked...

Our e-mail is 365 not connected to our Active Directory.

I honestly do not see how this is a Active Directory problem and this co-worker has previously blamed network or Active directory for …
Bringing Advanced Authentication to the SMB Market
Bringing Advanced Authentication to the SMB Market

WatchGuard announces the acquisition of advanced authentication provider, Datablink, with one mission – to bring secure authentication to SMB, mid-market, and distributed enterprises with a cloud-based solution, ideal for resale via their established channel & MSSP community.

Hi There,

We have recently acquired a  new mail base and we need to sync the data over to our new server.
However we have encountered a problem where the passwords are encrypted.
There are 2 passwords, digest password: digestPassword = {SSHA}TWcg67eMGQn428d3dS4HbZJqytpFMkku182nLQ==
and encrypted password. I was given a key RSA-X.509 to decrypt it but unsure how to go about so.
Please could someone kindly advise as we have around 50k mailboxes to copy over.
Today is the last day to enroll in June’s Course of the Month. With ransomware attacks on the rise this year, we encourage all members of our community to enroll and avoid becoming part of 2017's statistics. Premium members, Team Account members, and Qualified Experts will have 30 days after enrollment to complete the course. Don’t miss this opportunity to enhance your security!
I have a IPSec tunnel to a remote location. From within the network I am able to access all resources over IPSec tunnel. Users who are connecting in over Cisco's Anyconnect are unable to reach the resources over the IPSec tunnel.
Today's update on Petya
Previously, it was believed that the ransomware would not begin encrypting until an hour after the initial infection. It is now been discovered that it begins encrypting the first 1MB of the below file types upon infection. Therefore turning off your device when viewing the reboot message, will not stop encryption.

It is also now being disputed if the goal of this attack was to collect Bitcoin or cause mass destruction in the devices it infects.

Files types:
.3ds .7z .accdb .ai .asp .aspx .avhd .back .bak .c .cfg .conf .cpp .cs .ctl .dbf .disk .djvu .doc .docx .dwg .eml .fdb .gz .h .hdd .kdbx .mail .mdb .msg .nrg .ora .ost .ova .ovf .pdf .php .pmf .ppt .pptx .pst .pvi .py .pyc .rar .rtf .sln .sql .tar .vbox .vbs .vcb .vdi .vfd .vmc .vmdk .vmsd .vmx .vsdx .vsv .work .xls .xlsx .xvd .zip
Gain the added security of knowing you are prepared and properly protected against future ransomware attacks, such the Petya attack, with this free course! Premium members, Team Account members, and Qualified Experts have 3 days to enroll for June’s Course of the Month. Once you enroll, you have 30 days to complete the course.


Internet Protocol Security

Internet Protocol Security (IPsec) is a protocol suite for secure Internet Protocol (IP) communications by authenticating and encrypting each IP packet of a communication session. IPsec includes protocols for establishing mutual authentication between agents at the beginning of the session and negotiation of cryptographic keys to be used during the session. IPsec can be used in protecting data flows between a pair of hosts (host-to-host), between a pair of security gateways (network-to-network), or between a security gateway and a host (network-to-host). IPsec is an end-to-end security scheme operating in the Internet Layer of the Internet Protocol Suite.

Top Experts In
Internet Protocol Security