Internet Protocol Security




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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.

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Is there a way to block an entire folder including the .exe everything inside a folder from connecting to the internet? If Windows 10's Firewall can't is there another Firewall that can?
Retailers - Is your network secure?
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I know that my cipher suites are causing the issue with not being able to connect to certain sites - I'm not sure how or why but somehow it's only allow HTTP connections and is not allowing HTTPS connections (windows update can't check for updates, can only browse http websites)

I also can't connect to my IIS site as it's HTTPS as well - there are no errors in the logs

I know the cipher information is in computer\HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL

What do I need to do to check/fix to allow both http and https connections on this server?

See attached photo

I've seen this issue before but cannot for the life of me remember what I need to do to resolve it

IIS 7.5 - Win Server 2008 R2
I have a Windows 2016 Hyper-V server box that came with two network cards. First NIC is connected to internal LAN (192.168.1.x) and 2nd NIC is connected directly to ISP Internet modem (therefore, it receives a dynamic public IP address given by ISP DHCP server). On 2nd NIC,  I intend to create a virtual machine ("TESTVM") where I like to try to open some suspicious email attachments or click on website links (to find out whether they are malicious). I have installed Malwarebytes Anti-Exploits/Anti-Malware/Ransomware on this VM and it sends me email alerts whenever it detects "suspecious" activity.
I plan on connecting to this VM thru remote desktop connection program (port# 3389, 3390 .. etc) using Dynamic DNS.
Having said that, I know a lot of experts would go against the idea of exposing the server to public internet.

I know that I could put another router (192.168.2.x) between 2nd NIC and ISP internet modem to enhance security, but what I like to know is how am I venerable as it is?
How could hackers penetrate to this server when the only account is "administrator" with secure password?

Thanks you for your insight.
Hi, So this used to work so I am baffeled at the moment. Lets say the networks are below.. 2 Cisco ASA 5501 one on side 5510 on other.

VLAN location 1: X.X.20.0 /24
VLAN location 2: X.X.30.0 /24

I see on both asdm the icmp packages being transmitted, "built" never says fail.  but it does not ping on local clients.
if I do a traceroute from 5505 it atleast goes out a few hops.
but if I go to the 5510, I get zero hops, as if its not leaving the asa at all..

I see network objects defined for both, I have static routes defined for both

anything I am missing ? without me pasting my config I mean, just anything very obvious?? TY ALL
Need help on configuring IPsec VPN site to site VPN Tunnel between two sites. But the requirement is that I have to NAT all my local subnet (e.g. to single IP (e.g. and send it through the tunnel for remote traffic (e.g. Please see the attached diagram for details.

I am OK setting up IPsec Site-to-Site Tunnel using the wizard between local network to remote network  But this specific remote site require we NAT all our local network to a single private IP and send it over the tunnel... as they will only accept traffic from this NATed single private IP ( only.

Cisco ASA 8.x

I'm french, so my english isn't perfect...

I have a client with this network :
- 10 remote sites with CISCO ASA 5505 connected to a CISCO ASA 5520 (in the main agency).

Example :
A is connected to B (IPSec Tunnel)
B is connected to C (IPSec Tunnel)

I would like for site A to be able to get to site C through site B without create a new VPN Tunnel...

I don't know how I can do that...
I have the above phone trying to VPN with a Dell SonicWall TZ400. When I put in the VPN information, listed below, the phone fails and gives me error codes that Phase 2 no response. I will list the three error codes I also see, if anyone can point me in the right direction.


SonicWall VPN Settings:

Policy Type: Tunnel Interface
Authentication Method: IKE using Preshared Secret

IPsec Primary Gateway Name or Address:

IKE Authentication:

Local IKE ID: Domain Name
Peer IKE ID: Domain Name

IKE (Phase 1) Proposal:

Exchange: Aggressive Mod
DH Group: 2
Encryption: 3DES
Authentication: SHA1
Life Time: 28800

IPsec (Phase 2) Proposal:

Protocol: ESp
Encryption: 3DES
Authentication: SHA1
Enable Perfect Forward Secrecy: Checked
DH Group: 2
Life time: 28800

In advanced tab, the only thing checked is Keep Alive.


Server: 50.XX.XX.209
PSK: *****
IKE Parameters: DH2-3DES-SHA1
IPSEC Parameters: DH2-3DES-SHA1
VPN Start Mode: Boot

Password Type: N/A
Encapsulation: RFC
IKE Parameters: DH2-3DES-SHA1
IPSEC Parameters: DH2-3DES-SHA1

Copy TOS: No
File Srvr: Blank
QTest: Disable
Connectivity Check: Never


IKE Phase1 received notify
Error Code: 3997698:18
Module: NOTIFY:305

IKE Phase2 no response
Error code: 397700:0
Module: IKMPD:353

IKE Phase2 no response
Error code: 3997700:0
Module: IKECFG:1184
Hi Experts,

On our public-facing OWA server on IIS 7, we turned on IP Address and Domain Restriction. If from the log we detect any IP trying brute force to log into our Web Outlook interface, we will put the IP into "Deny Restriction Rule" in the hope that IP will be 'blocked', meaning not even able to get the login screen. Actually it seems to be a wishful thinking since we noticed one of the IP we already added in the 'Deny' list that particular ip still keeps showing up in the log and we can see it got the login form and then denied with sc-status 401-1.

My question is, it seems this feature does NOT "block" the IP from getting the login form, but instead simply "deny" their login request. Is it correct?
Hello Expert,

I have an issue with an IPSEC configuration on a ASR 1001-X. I use a crypto map based implementation but it's not working. I make a capture on the device facing the ASR and I have no ESP packet out of the ASR. I can ping the remote IPSec peer but nothing else.

Below the configuration, did you see something missing ?

ip vrf Ivrf
 description Clear side VRF
ip vrf Fvrf
 description Cypher side VRF (front door vrf)
crypto keyring Key_test vrf Fvrf
  pre-shared-key address key toto123
crypto isakmp policy 1
 encr 3des
 hash md5
 authentication pre-share
 group 2
crypto isakmp profile ISAK_TEST
   vrf Ivrf
   keyring Key_test
   self-identity address
   match identity address Fvrf
   initiate mode aggressive
   local-address Loopback2
crypto ipsec transform-set ESP-NULL esp-null esp-sha-hmac
 mode tunnel
crypto map CRYPTO_TEST 1 ipsec-isakmp
 description TEST
 set peer
 set security-association lifetime kilobytes disable
 set security-association lifetime seconds 28800
 set security-association idle-time 28800
 set transform-set ESP-NULL
 set isakmp-profile ISAK_TEST
 match address CRYPTOACL_TEST
 reverse-route remote-peer static
interface Port-channel1.419
 description cypher side interface
 encapsulation dot1Q 419
 ip vrf forwarding Fvrf
 ip address
 standby version 2
 standby 419 ip
 standby 419 …
We have several small networks connected to our corporate office over IPSec tunnels. At our office, we have a Windows 2008 R2 server running NPS performing RADIUS authentication with WAPs. Up until now, everything has been running fine. But we connected a new office and we can't get any of our client working on the WAP at the remote office. We can see the RADIUS authentication request come from the WAP across the VPN and hit the server, the server responds back to the WAP, but then nothing happens on the requesting client. All other traffic over the VPN comes across without issue.

The difference at this new network is that we're trying a Netgate PFsense firewall instead of our normal SonicWall. The only thing I can come up with is the Pfsense firewall is interfering with the WAP in some form, but so far I haven't found anything that would prevent that.

The WAPs being used (at both old and new locations) are Open-Mesh MR1750v2
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Hello Community,

I have created an VPN as shown in the attached configs. The tunnel is up and ipsec appears to working fine. However, I'm unable to ping the address (interface on the router) from the other site with address I think the problem might be that traffic isn't being recognized in the ipsec tunnel as shown here:

cisco-csr-vpn#show crypto ipsec sa

interface: Tunnel1
Crypto map tag: Tunnel1-head-0, local addr

protected vrf: (none)
local ident (addr/mask/prot/port): (
remote ident (addr/mask/prot/port): (
current_peer port 4500
PERMIT, flags={origin_is_acl,}
#pkts encaps: 80, #pkts encrypt: 80, #pkts digest: 80
#pkts decaps: 83, #pkts decrypt: 83, #pkts verify: 83
#pkts compressed: 0, #pkts decompressed: 0
#pkts not compressed: 0, #pkts compr. failed: 0
#pkts not decompressed: 0, #pkts decompress failed: 0
#send errors 0, #recv errors 0

local crypto endpt.:, remote crypto endpt.:
plaintext mtu 1422, path mtu 1500, ip mtu 1500, ip mtu idb GigabitEthernet1
current outbound spi: 0xEC0058AA(3959445674)
PFS (Y/N): N, DH group: none

inbound esp sas:
spi: 0xE8D52690(3906283152)
transform: esp-256-aes esp-sha-hmac ,
in use settings ={Tunnel UDP-Encaps, }
conn id: 2002, flow_id: CSR:2, sibling_flags FFFFFFFF80000048, crypto map: Tunnel1-head-0
sa timing: remaining key lifetime (k/sec): (4607992/3051)
IV size: 16 bytes
replay …
I need to migrate a VPN tunnel with 70 lines of cryptomap. The PAN GUI appears to permit my only adding
a single line at one time. I see that I can add security rules via CLI. Perhaps there is something similar for
adding an IPsec tunnel and its Proxy IDs? Any other thoughts apprecaited.

set rulebase security rules Inbound-SSH from corpfw2-untrust
set rulebase security rules Inbound-SSH to corp-vpn
set rulebase security rules Inbound-SSH source RFC-1918
set rulebase security rules Inbound-SSH destination any
set rulebase security rules Inbound-SSH source-user any
set rulebase security rules Inbound-SSH category any
set rulebase security rules Inbound-SSH application [ ssh ssh-tunnel]
set rulebase security rules Inbound-SSH service application-default
set rulebase security rules Inbound-SSH hip-profiles any
set rulebase security rules Inbound-SSH action allow
set rulebase security rules Inbound-SSH profile-setting group Corp-Default-SecPro1
set rulebase security rules Inbound-SSH log-start yes
set rulebase security rules Inbound-SSH log-setting logmaster1
set rulebase security rules Inbound-SSH disabled yes
Is there anyway to monitor the email clients IP addresses on Exchange 2016 ?? especial on smart phones
Hello Master.
i have a fortigate  60D and a Cyberoam, and i had been configure VPN IPSec between it.
the VPN is connected but i cant access the computer (RDP, PING, WEB, HTTPS) in the other side.
i try to allow connection in filter rule in the both side, but i still cant access.
i try step by step in this link, and still cant access
any suggestion for my case? some tutorial link or something i must to do.

Thanks Very Much
hello everyone,

I have Juniper SSG5, and I try to connect VPN site to site. I cannot find the problem of this message.

"Rejected an IKE packet on ethernet0/0 from xx.xx.xx.x:500 to xx.xx.xx.x:500 with cookies ... because An unencrypted packet unexpectedly arrived."

Please anyone help me.

Thank you.

This year I have a project to set up Cisco PFR technology to optimize company's network. The company has 6 offices (A to F) all over the world which connects to each other by IPSec over GRE tunnels over the internet.

Unlike some traditional PFR scenarios, we don't have a hub-spoke deployment. Instead, the 6 offices are fully meshed with each other. Each office has 1-2 VPN routers and each VPN router linked with two different ISPs. Any two offices are connected over encrypted point to point GRE tunnels.

My questions is: am I able to configure PFRv3 based on this point to point GRE tunnels deployment rather than changing the whole infrastructure to DMVPN/multi-point GRE tunnels? Is it supported by some Cisco user guide?

What we want to achieve is to always use the low latency/packet loss GRE tunnel as the active network connection between the two offices/countries. The current network topology is too complicated so we want to minimize the changes. Configurations samples of one office are as below:

[ Cisco ISR4431 ]

interface Tunnel22
  ip address
 tunnel source x.x.x.x
 tunnel destination x.x.x.x
 tunnel protection ipsec profile corporate-ipsec
interface Tunnel23
 ip address
 ip tcp adjust-mss 1300
 tunnel source x.x.x.x
 tunnel destination x.x.x.x
 tunnel protection ipsec profile corporate-ipsec
interface GigabitEthernet0/0/0
 ip address x.x.x.x
I'm not a networking expert, it's my least favorite part of IT, so I may well have missed something during setup, but I had thought that in my research I read that IP Security would be transparent to applications. Because of that, I am very confused as to why this error started appearing in Internet Explorer after I rolled out the IPSec policy:

IE Error from IPSec
Clients on the network connect to the Webserver that hosts the site without issue.  This issue started when the database server, picked up the settings and the webserver and DB server started communicating encrypted.  Also, TLS 1.0, 1.1, and 1.2 are enabled on all machines in our domain through GPO, SSL 2.0 and 3.0 are disabled in the same policy.

Please let me know if you need more info, but any help that anyone can provide will be greatly appreciated.
I am having issues with 4 sties. Each have 4 ipsec vpn tunnel inbetween to cross connection and application access.

But only one application is giving me an issue. The server is on Site (A) and site (B) but soon to be (A) only. Two other site (C) and (D) are VPNing in to site (A) to access the server.

When you minimize the application (which is working true a RPD connection) and work on something else, once you get back to the application there is a reconnecting issue. Takes about 2-3 mins to get the application back working.

I've been having some issue with the VPN and I am not a pro with vpn log. Can anyone help me?

2017-02-01, 08:12:08      VPN Log      [g2gips0] #8461: [Tunnel Established] IPsec SA established {ESP=>0xc7488fd9 < 0xcd1b9f35}
2017-02-01, 08:12:08      VPN Log      [g2gips0] #8454: [Tunnel Authorize Fail] ignoring Delete SA payload: PROTO_IPSEC_ESP SA(0xcee3770f) not found (maybe expired)
2017-02-01, 08:15:15      VPN Log      [g2gips0] #8462: [Tunnel Established] sent MR3, ISAKMP SA established
2017-02-01, 08:19:30      VPN Log      [g2gips3] #8463: [Tunnel Established] sent QI2, IPsec SA established {ESP=>0xc8dcbf5b < 0xcc9dcbd1 AH=>0xca3fff03 < 0xc2c1a9a1}
2017-02-01, 08:19:30      VPN Log      [g2gips3] #8456: [Tunnel Authorize Fail] ignoring Delete SA payload: PROTO_IPSEC_ESP SA(0xcf402c1f) not found (maybe expired)
2017-02-01, 08:19:30      VPN Log      [g2gips3] #8456: [Tunnel Authorize Fail] ignoring Delete SA payload: PROTO_IPSEC_AH SA(0xc8a48df1) not found (maybe expired)
2017-02-01, …
Current config: ASA-5505, vASA 8.2 (5).  Serves our 1-15 host network, and has a site-to-site IPSec VPN to a client configured (establishes automatically).  Of course, all non local or internet traffic is sent to the VPN.  Been working great for over a year no hiccups.
Eth0 is the "outside" interface (security level 0), Eth1-7 are the "inside" interfaces, security level 100.  All Ipv4, no ipv6.

I'm adding a remote office, and I want the remote office to effectively act as part of the original local office.  It will have its own 5505 device, and a static ip address(s) from our ISP.  I plan to use a 2nd site-to-site VPN to connect.  The particulars are where I'm lost a bit - Cisco firewall configuration is not my forte.  How I envision the remote office to behave is hosts there will obtain their ip address via the local 5505.  The VPN there needs to act pretty much as a NAT bridge.  The remote office will still need the same access to our site-to-site client, and also appear as hosts "of" our original local network.  They would have their own ip4 subnet.  The default gateway would be the inside ip address of the local 5505.
So it seems easy on the side of the new office I think.

Now the current local office:
Here's my guesses so far:  I have multiple public ip's to use, so set another "unused" current 5505 eth physical port as one of our other public ip's?  It appears this is set as a different VLAN? (Eth0 is currently VLAN2, Eth1-7 is VLAN1).  Then, create a …
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I would like to configure Hong Kong Site H3C MSR 810 using IPSec site to site VPN to Singapore pfSense FW .Please provide the cli command (Comware 7)how to configure in MSR810  .Singapore site has configured their FW as configuration in attachment HQSG-pfSense.txt and Hong Kong configuration file are attachment H3CMSR810.txt

pfSense FW
Local LAN:
Hello Everyone,

I am working to set up a raspberry pi as a vpn through my pfsense router. I have the pi configured and I am now having issues getting it to pass through the firewall to a public ip. If that won't work I'm looking for a username/password based vpn akin to pptp to add simplicity for my users (they don't want to use another client like open vpn) I'm fairly new to configuring vpns and I'm looking for a little guidance.
Dear All,

I need help with the following:

I have three sites, A (Core is a Cisco 3560-X), B (Core is a Cisco 3560-X) and C... Site C is from an external entity that's connected to site B’s 2921 router and only accepts connections, from our side, from a /24 network they gave us…

For site A and B, they are connected using two Cisco Router 2921 (each are connected directly to the Ciscos 3560-X) that's using an IPSec Tunnel to encapsulate the communication for the internal networks...

Basically I want to reach site C, from site A, but because I need to NAT A’s internal network to the one that C accepts... This network is also declared on site B's 3560-X

How can I achieve this?

Some more information:

Site A internal network:
Site C network that they accept:

I know that this may seem very little information, but please ask and I’ll reply.

I have been trying to install Openswan on Ubuntu, but I keep getting the following error,

029 "L2TP-PSK-noNAT": cannot initiate connection without knowing peer IP address (kind=CK_TEMPLATE)

This is my ipsec.conf file

config setup
    #in what directory should things started by setup (notably the Pluto daemon) be allowed to dump core?

    #whether to accept/offer to support NAT (NAPT, also known as "IP Masqurade") workaround for IPsec

    #contains the networks that are allowed as subnet= for the remote client. In other words, the address ranges that may live behind a NAT router through which a client connects.

    #decide which protocol stack is going to be used.

    # Send a keep-alive packet every 60 seconds.

conn L2TP-PSK-noNAT
    #shared secret. Use rsasig for certificates.

    #Disable pfs

    #the ipsec tunnel should be started and routes created when the ipsec daemon itself starts.

    #Only negotiate a conn. 3 times.


Hi all i have a tunnel configured between two sites.

Site A
ADSL internet connection connected to ATM0
Site A has a static ip address block assigned which is used for all inbound connections from the internet
GRE IPSEC tunnel configured to site B
Nat rule for one of the static ip's through to the mail server at site b
Nat rule for one of the static ip's through to the web(outlook OWA) server at site b

Site B
Fibre Internet connected via ethernet wan interface
GRE IPSEC Tunnel Configured to Site A
Mail Server connected on internal vlan interface

Problem is i'm getting a lot of issues with smtp inbound. the errors reported are timed out waiting for end of data which i'm finding on the internet is caused possibly due to fragmentation.
I also cannot really use the internet on the mail server also as all traffic outbound traverses the tunnel, however inbound web mail works fine as does all other mobile mail functionality.

I suspect its got something to do with the MSS or MTU settings however i'm not sure how to set them correctly. I have played around with the MSS on the tunnel interface and still cant get internet working on the mail server

tunnel config is same both ends and looks like the following:
interface Tunnel0
 description Kuala Lumpur to Melbourne Link
 ip address
 ip mtu 1400
 ip virtual-reassembly in
 tunnel source Dialer1
 tunnel mode ipsec ipv4
 tunnel destination x.x.x.x
 tunnel protection ipsec …
I had this question after viewing Site-to-Site VPN OpenSWAN in AWS VPC to a Sonicwall.

I now have 7 tunnels from StrongSWAN setup and connected to my different Sonicwall locations.  When the tunnel first comes up, traffic passes back and forth as expected.  If I come back and check the status of the tunnel several hours later, I find that i can no longer ping or make connections across the tunnel.  If I issue an ipsec restart, the traffic immediately begins to come through.

ipsec status all shows all of the tunnels as ESTABLISHED.

      AWS2SONCIWALL{564}:  INSTALLED, TUNNEL, reqid 89, ESP in UDP SPIs: ce0c3d37_i 8997eece_o
      AWS2SONCIWALL{564}: ===

Internet Protocol Security




Articles & Videos



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.