Check "show crypto ipsec sa" on R0 and confirm there are active SAs to R4 and the counters encaps|decpas increase when PC1 pings the server. Again the "show crypto ipsec sa" would confirm the traffic selectors, provide the output for further review. This results in two GRE + IPsec packets of 1500 (1476 + 24 = 1500) and 68 (44 + 24) bytes each. <> Refer to Adjusting IP MTU, TCP MSS, and PMTUD on Windows and Sun Systems for information about possible Maximum Transmission Unit (MTU) issues. endobj I now can ping from PC0. Refer to PIX/ASA 7.x and later : VPN/IPsec with OSPF Configuration Example for more information on how to configure for a VPN/IPsec with Open Shortest Path First (OSPF) without a GRE tunnel on Cisco PIX Security Appliance Software Version 7.x or Cisco Adaptive Security Appliance (ASA). A setting of 1400 is a common practice and will ensure unnecessary packet fragmentation is kept to a minimum. )R4 In certain earlier versions of Cisco IOS release, fast switching on the tunnel interface has to be disabled for it to work, due to a bug. It could also potentially be that because your crypto ACL permits "ip" from the local networks, traffic is being encrypted over the crypto map without being sent over the tunnel interface. Learn more about how Cisco is using Inclusive Language. '2I?hGQcYZE 7e6?O _nbWOwwRYQg]v8& ,4|oX=h^ Ct[0l%HnF This document illustrates how to route between different networks that use a routing protocol and non-IP traffic with IPsec. Note:Refer to Important Information on Debug Commands before you use debug commands. The same configuration must be repeated for R2: Now both networks are able to freely communicate with each over the GRE Tunnel. With GRE IPSec transport mode, the GRE packet is encapsulated and encrypted inside the IPSec packet, however, the GRE IP Header is placed at the front. Refer to Cisco Technical Tips Conventions for more information on document conventions. Use these resources to familiarize yourself with the community: Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. show crypto isakmp sa Shows the phase 1 security associations by displaying the router's IKE SA. In this section, you are presented with the information to configure the features described in this document. refer to Cisco Technical Tips Conventions. This is the topology that we will use: Above we have 3 routers. FoEsgUj4_6B*w=w|r|!`MIT*Cr*RTT.yp^(NRiG,6m%Z`T3)uzvG^`UA5{Wy0=CmH,Q'v{M IPSec Transport mode is not used by default configuration and must . 1 0 obj Now we need to create the transform set used to protect our data. This document uses the network setup shown in the diagram below. jLky To configure Generic Routing Encapsulation (GRE) over an IPSec tunnel between two routers, perform these steps: Create a tunnel interface (the IP address of tunnel interface on both routers must be in the same subnet), and configure a tunnel source and tunnel destination under tunnel interface configuration, as shown: interface Tunnel0. This provides us with the necessary military-grade encryption and peace of mind. Configure In this section, you are presented with the information to configure the features described in this document. For example, access-list 101 permit gre host #.#.#.# host #.#.#.# (where the first host number is the IP address of the tunnel source of the GRE tunnel and the second host number is the IP address of the tunnel destination). Prerequisites Requirements Ensure that you meet these requirements before you attempt this configuration: I'm trying to build a GRE Tunnel with IPSec encryption (I may be phrasing this incorrectly, I realize). You can view the bug details for this issue at CSCdm10376 (registered customers only) . Note:To find additional information on the commands used in this document, use the Command Lookup Tool (registered customers only) . ;z={ Z4*3PTP;fA\70A*1ZZA6V$Q LOk;?Z(_ J?Du=c};+96R.Lai]g3ZGAdw?3dW@Z+._$J5;l#45i!1gg$XPn,i(:_wVI+/* :s4'Mm* show crypto isakmp saShows the Internet Security Association Management Protocol (ISAKMP) Security Association (SA) built between peers. First step is to configure an ISAKMP Phase 1 policy: The above commands define the following (in listed order): Next we are going to define a pre shared key for authentication with R1's peer, 2.2.2.10: The peers pre shared key is set to firewallcx. Learn more about how Cisco is using Inclusive Language. Define local GRE tunnel interface and assign it an IP address by typing the following commands: SFN_Router(config)# interface tunnel 0 SFN_Router(config-if)# ip address 196.100.101.1 255.255.255. Refer to Cisco Technical Tips Conventions for more information on document conventions. Also remember that the ip address given as tunnel destination should be globally routeable. \81hf&vtD@,_k fYk8||ckz4WknDjv Wm\Ku|N?h_O&#H}:lj2 4!Lk_` GRE (Generic Routing Encapsulation) is a simple tunneling technique that can do this for us. Here are some configuration considerations: With IOS 12.2(13)T software and later (higher numbered T-train software, 12.3 and later), the configured IPSec crypto map only needs to be applied to the physical interface and is no longer required to be applied on the GRE tunnel interface. This key will be used for allISAKMP negotiations with peer 2.2.2.10 (R2). Ide appreciate any help on understanding whats happening and why. The diagram below shows the encapsulation procedure of a simple - unprotected GRE packet as it traversers the router and enters the tunnel interface: While many might think a GRE IPSec tunnel between two routers is similar to a site to site IPSec VPN (crypto), it is not. All rights reserved. YVj\F:%/=9w~f/ _xl>Wd* =}l"&tyzWeN!=eBs/e-MLIca zHl)4hQ)rmZI)y\_DNfI" c;%H%NlN^ $;#Yj,S++"X.%;S3e&T&E:'O~{''OKg^CcarxNlYtS*@sc,M7Q5INceo 9|b3sjpAyL6F LXT5,Sr{oo/{ WW:o,tnvXT=n76.jA7k*:unu ]$|iM7M:1B%PWO,&(juL show crypto engine connections active Displays a list of active SAs with their associated interfaces, transforms and counters. The entire GRE payload will be encrypted using the same IPSec link. The information in this document is based on these software and hardware versions: Cisco 3600 that runs Cisco IOS Software Release 12.4(8), Cisco 2600 that runs Cisco IOS Software Release 12.4(8), PIX Firewall (Lion) Software Release 6.3(5), PIX Firewall (Tiger) Software Release 6.3(5). from the MSBG to a loopback address on the Cisco router. <> Before it can do this, IKE must negotiate an SA (an ISAKMP SA) relationship with the peer. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. This section captures the debug command outputs on the routers configured with IPSec. >{3*zGb]>bCqz{M]g[^A*kr}l~4ba4W{8GXB#}YXSfarz # eMww`l5683"UG1Fv$,18uORzmgu_GA As with R1, R2 router will inform us that the Tunnel0 interface is up: At this point, both tunnel endpoints are ready and can see each other. 11 0 obj To configure Generic Routing Encapsulation (GRE) over an IPSec tunnel between two routers, you can refer to these steps as follows: 1. Make sure that the GRE tunnel works before applying the crypto maps. RoutertoRouter IPSec (RSA Keys) on GRE Tunnel with RIP Configuration Example Document ID: 29780 Contents Introduction Prerequisites Requirements Components Used Conventions . endobj Im trying to configure this lab and PC1 can ping Server, but for PC0 to ping server I had to configure a static route (, ip route 10.0.0.0 255.0.0.0 192.168.0.5), but not on PC1 (All routers have EIGRP configured.). Tracing route to 10.0.0.2 over a maximum of 30 hops: Find answers to your questions by entering keywords or phrases in the Search bar above. endobj All rights reserved. 9 0 obj to configure for a VPN/IPsec with Open Shortest Path First (OSPF) without a GRE tunnel on Cisco PIX Security Appliance Software Version 7.x or Cisco Adaptive Security Appliance (ASA). Note:Before issuing debug commands, please see Important Information on Debug Commands. show crypto ipsec sa Shows the phase 2 security associations by displaying a detailed list of the router's active IPSec SAs. Both routers are connected to "the Internet" using the ISP router. A!dlD6&r!x]3M Refer to Troubleshooting the PIX to Pass Data Traffic on an Established IPSec Tunnel for additional information on troubleshooting a PIX and IPsec tunnel. The Output Interpreter Tool (registered customers only) (OIT) supports certain show commands. 10.31.4.52 a 10.31.4 . GRE tunnels greatly simply the configuration and administration of VPN tunnels and are covered in our Configuring Point-to-Point GRE VPN Tunnels article. (because the ip packet is first encapsulated by GRE and then AH/ESP headers are added). GRE encapsulates the IP fragments, which adds 24 bytes to each packet. !1^a@DM!C2) t^B`(dIC2JEd~Q"4BBPE/56ckT/@LKwjJxP,3l{RT[ce/qT=dBGYVF?)K-S:X $ z-+V,9.6H@tH)#`FE-%\TtP"fL1h4d(-PF}#7jp$ge\y&.k9z%JEp1d?3 Xvy07Ierbv'X&_~Nu0?b[oJF6E%+Z_4tE|KjVRwp6tqCsxkW} W=,O8bYf1Hu\0 'gWYtlOg} nF%7m:1C>{.mp_sJ=Vs&2u[w0~sC=tPBp~r]rs&|u-O46>v j?m(qcNn|'gSQ3Vxf3sU/. Ive checked configurations but I must be missing something. Refer to Configuring IPsec RoutertoRouter Hub and Spoke with Communication Between the Spokes for %PDF-1.2 The information in this document is based on the software and hardware versions below. Generic Routing Encapsulation (GRE) is a tunneling protocol developed by Cisco that allows the encapsulation of a wide variety of network layer protocols inside point-to-point links.. A GRE tunnel is used when packets need to be sent from one network to another over the Internet or an insecure network. endobj The documentation set for this product strives to use bias-free language. ujIURI;o\'x=kT/^HhoKpB8xZHAn60;756p|9Ek6Y\lUdY%T2nl+zS!V\v346/^&MT{ku6vQ\=51-5SNMJSe4@0q*:cHBdN*k#C/Ig($ q#I*! ipsec tunnels - GRE tunnels - gre over ipsec Certifications All Certifications CCNA CyberOps Associate CyberOps Professional DevNet Associate DevNet Professional DevNet Expert CCNP Enterprise CCNP Security CCNP Data Center CCNP Collaboration CCNP Service Provider CCIE Enterprise Infrastructure CCIE Enterprise Wireless CCIE Data Center CCDE For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Certain show commands are supported by the Output Interpreter Tool (registered customers only) , which allows you to view an analysis of show command output. Yf`lx- k[r refer to Cisco Technical Tips Conventions. The connection is encrypted with the industry- . <> IPSec VPN tunnels can also be configured using GRE (Generic Routing Encapsulation) Tunnels with IPSec. Note:The IP addressing schemes used in this configuration are not legally routable on the Internet. The documentation set for this product strives to use bias-free language. But this is what I'm using and I cannot for the life of me figure out why it isn't building a security association. debug crypto ipsec View the IPSec negotiations of phase 2. debug crypto isakmp View the IKE negotiations of phase 1. % First step is to create our tunnel interface on R1: All Tunnel interfaces of participating routers must always be configured with an IP address that is not used anywhere else in the network. x`}'htM'j-lBwtjRzqVEv)`X%[Q{RilDZxh5Qkn HYW"iQX%(E ,J`QX%(E 0-z~Y$@`|Dw/67 0#x;CC EaQ(o FP(+axHXjDf&4rHPj/@dUQLKU,[7hP @bxB@vnErmg} l[P7#5Uz@HRf D 15E|BEK*hX$.v;w"OI4\"92G-/ ! Part Two - Configuring the GRE tunnel on the Cisco router Step 1 - Enter configuration mode. GRE tunnel uses a tunnel interface a logical interface configured on the router with an IP address where packets are encapsulated and decapsulated as they enter or exit the GRE tunnel. I also checkedisakmp sa and an association wasnt built successfuly between R3 and R0 even though it was using the tunnel (very odd). The previous tutorial shown GRE tunnel configuration between Cisco router and Linux Core. }H5IU~agRmLg|2!IGXsPHb79 w)D"5sT6;P:', bI0KV]MA0GDat*4Omcr\NCoeffF There is currently no verification procedure available for this configuration. Configure In this section, you are presented with the information to configure the features described in this document. Our example below covers GRE IPSec Tunnel mode. <> show crypto map Displays the crypto maps configured on the router along with its details such as crypto access lists, transform sets, peers etc. An icmp echo from one end will confirm this: Again, this result means that the two tunnel endpoints can see each other. Weve named this TS: Finally, we create an IPSec profile to connect the previously defined ISAKMP and IPSec configuration together. V:{z1@Kgdb @MfUc[QUUt_4L:/ R0:access-list 101 permit ip 10.0.0.0 0.255.255.255 172.16.0.00.0.3.255crypto isakmp policy 10encryption aes 256authentication pre-sharegroup 5crypto isakmp key vpn-key address 64.102.46.2crypto isakmp key vpn-key address 64.100.13.2crypto ipsec transform-set R0_SET esp-aes esp-sha-hmaccrypto map R0_MAP 101 ipsec-isakmpset peer 64.102.46.2set peer 64.100.13.2set transform-set R0_SETmatch address 101interface serial 0/0/0crypto map R0_MAP, interface tunnel 0ip address 192.168.0.1 255.255.255.252tunnel source serial 0/0/0tunnel destination 64.100.13.2tunnel mode gre ip, interface tunnel 1ip address 192.168.0.5 255.255.255.252tunnel source serial 0/0/0tunnel destination 64.102.46.2tunnel mode gre ip, ip route 172.16.0.0 255.255.252.0 192.168.0.2ip route 172.16.4.0 255.255.252.0 192.168.0.6, R3:access-list 101 permit ip 172.16.4.0 0.0.3.255 10.0.0.0 0.255.255.255crypto isakmp policy 10encryption aes 256authentication pre-sharegroup 5crypto isakmp key vpn-key address 209.165.118.1crypto ipsec transform-set R4-SET esp-aes esp-sha-hmaccrypto map R4_MAP 101 ipsec-isakmpset peer 209.165.118.1set transform-set R4-SETmatch address 101interface serial 0/0/0crypto map R4_MAP, interface tunnel 1ip address 192.168.0.6 255.255.255.252tunnel source serial 0/0/0tunnel destination 209.165.118.1tunnel mode gre ip, R4:access-list 101 permit ip 172.16.0.0 0.0.3.255 10.0.0.0 0.255.255.255crypto isakmp policy 10encryption aes 256authentication pre-sharegroup 5crypto isakmp key vpn-key address 209.165.118.1crypto ipsec transform-set R3-SET esp-aes esp-sha-hmaccrypto map R3_MAP 101 ipsec-isakmpset peer 209.165.118.1set transform-set R3-SETmatch address 101interface serial 0/0/0crypto map R3_MAP, interface tunnel 0ip address 192.168.0.2 255.255.255.252tunnel source serial 0/0/0tunnel destination 209.165.118.1tunnel mode gre ip. The main drawback of GRE protocol is the lack of built-in security. y 2=z$YTCeFVEcgd*8c1 a %Y^5t4AjwA k3* Suc4juv`(vbx=lP=76U=l$ >$Y>s*{0Ez*V-2>g]el@u lPeWkF+=/p1;c_zb(^90PRsI_\ #$.e&r0He9eO*'@{@?>:|; ,8{YSBr.T4.>[O\u-;J8`b0*kmk=D'F q5!s[wSVt&2?,Hhjku6UV&>ylVhqX&%an_o?Q[5 dv]KIz6 This section describes how to configure two IPSec VPN tunnels on Cisco 881 ISR running Cisco IOS 15.0. 2022 Cisco and/or its affiliates. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. IPSec encryption involves two steps for each router. Computer B 21.251.251.121.31.2. The above commands defines the following: Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds: Success rate is 100 percent (5/5), round-trip min/avg/max = 1/3/4 ms, IKE SA: local 1.1.1.10/500 remote 2.2.2.10/500, IPSEC FLOW: permit 47 host 1.1.1.10 host 2.2.2.10, OpManager - Network Monitoring & Management, GFI WebMonitor: Web Security & Monitoring, Cisco Routers - Configuring Cisco Routers, GRE and IPSec GRE Over IPSec - Selecting and Configuring Gre IPSec Tunnel or Transport Mode. ,}Q#-gyiH0ls 'J&V^dE)2M)/3F&\(b&rfQmuucR=nb~n~s(T4TC8V0r 1&1McB6H1t/G;LBG3ZN8t4-'WL_^>|r O|T_o=_Gyo~gk^`(:? Refer to Configuring Router-to-Router IPSec (Pre-shared Keys) on GRE Tunnel with IOS Firewall and NAT for information on how to configure the basic Cisco IOS Firewall configuration on a GRE tunnel with Network Address Translation (NAT). The information in this document was created from the devices in a specific lab environment. This effectively exposes the GRE IP Header as it is not encrypted the same way it is in Tunnel mode. O#fI2eQ'D{t"PLu>Fugc8 `N+3U I]N/ca%&C- Wqewb3%l``--J\'?^( %KZ~9Q6,[B1 ]ROlL>O/C!;Mb pHY+DV2 "@,$b)|J3O6qVmiiYg| SfAA2A~4(wP!]F@|gol, ( Z) f4j0J#R8% )/sO}yA6lhtb/O?xzSO"$>.{2N; View with Adobe Reader on a variety of devices, IP Security Troubleshooting - Understanding and Using debug Commands, IP Security (IPSec) Technology Support Page. Hence, the tunnel does not have any IP address configured. 7ywmo3AH|muZ[j g'CmgHOLP;R$E`gbng+VpyOTO8f@6 )z*v>kpl[wg`e.V|}^ 7x}_T|P#??[8.YA N>=1=3N7f1D9,bW1aj,5Y"8B k%t\Wj,(dq\[]! Only a single tunnel is operational at any time. `>j 7u]O~g4c]WddiMIb0KH)t;lN)z]\QsB5JF(z/Bp Generic Routing Encapsulation (GRE) is a tunneling protocol developed by Cisco that allows the encapsulation of a wide variety of network layer protocols inside point-to-point links. Normal IP Security (IPsec) configurations cannot transfer routing protocols, such as Enhanced Interior Gateway Routing Protocol (EIGRP) and Open Shortest Path First (OSPF), or non-IP traffic, such as Internetwork Packet Exchange (IPX) and AppleTalk. endobj NFrt<2tdc% (13)T software and later should still work; however, Cisco highly recommends that you apply it just on the physical interface. A major difference is that GRE tunnels allow multicast packets to traverse the tunnel whereas IPSec VPN does not support multicast packets. Although, you can configure the GRE Tunnel over the IPSec VPN for securing the GRE tunnel. Ch 4}NMbz}:-ud$i*15=O!q4|*' QT7fG*vP@uy7'MY3}C ^o2w*tmS^xO~~ rS erZXKhL~Po[lg5v811biLSh$&:$SOz:qiH*kv~.i%'=w%$i>VnXf8Qg_mIk{kL[ IUw\w(_'#=(k>ho#L `&efPQ;/|aMW;f\{`:n43V)T!0`D 4U4c$qn&WUGOw_=@ pnany]3]Qk>)D_l]UujdswC'xSAHQ+zgUgIJGed;bYW+PV/+GfHepQ$ 9rmMv|dv]~LK3`3GQ_F;(#C`pYxQpW-|XHAwm>b5{Tv&'Y>Zz!>UFj3AAnb:S aRN>PU-Y2GO5Nq_C6>Hg .dZ=n&0+6s-Cf=:4~cxCad=z03z7])bi4D$gy>;z?%>XYW{VwD/~v;d_-~{!HI >&}=N!Xqa)r75(efW_Wn0+2^Wfm^g> BlhH2z*#;haSA8|B;zSkxL:z xl1Dg,5[LdN|,wvbNkBg In large networks where routing protocols such as OSPF, EIGRP are necessary, GRE tunnels are your best bet. ."S,`IVOeew,tCB`osg!Xw ;=. endobj IPSec can be used to encrypt GRE tunnels to provide network layer security for non-IP traffic, such as Novell Internetwork Packet Exchange (IPX), AppleTalk, and so forth. 6 0 obj The HQ and Branch router each have a loopback interface that will represent their LAN connection. With GRE, a virtual tunnel is created between the two endpoints (Cisco routers) and packets . In order to configure the GRE tunnel, you must need connectivity between two remote routers through static Public IP address. In software versions prior to this release, IPSec crypto maps need to be applied to both the tunnel interface and the physical interface. Closing, we define the Tunnel source, which is R1s public IP address, and destination R2s public IP address. IPsec encrypts the two packets, adding 52 byes (IPsec tunnel-mode) of encapsulation overhead to each, in order to give a 1552-byte and a 120-byte packet. Turn off fast switching on the tunnel interface. crypto ipsec transform-set R0_SET esp-aes esp-sha-hmac crypto map R0_MAP 101 ipsec-isakmp set peer 64.102.46.2 set peer 64.100.13.2 set transform-set R0_SET match address 101 interface serial 0/0/0 crypto map R0_MAP . 8 0 obj All of the devices used in this document started with a cleared (default) configuration. Creating a point-to-point GRE tunnel without any encryption is extremely risky as sensitive data can easily be extracted from the tunnel and viewed by others. Posted in Cisco Routers - Configuring Cisco Routers. This section captures the show command outputs on the device Router1 when the IPX ping command is executed on Router1 destined for Router2. For this reason, plus the fact that GRE tunnels are much easier to configure, engineers prefer to use GRE rather than IPSec VPN. GRE IPSec Transport Mode. This configuration uses CLI commands. The big advantage of GRE protocol is that it encapsulates L3 and higher protocols inside the GRE tunnel so routing updates and other multicast traffic can be successfully transferred over the tunnel. v^Gip~>['ytJ_7{@?/?58QBP@rhiBZOFD1J)9vU+SP(3&u. The GRE tunnel in this example is purely used for transporting non-IP traffic. endobj You may have to install the VPN module in order for this to work. <> <>stream It is important to note that packets travelling inside a GRE tunnel are not encrypted as GRE does not encrypt the tunnel but encapsulates it with a GRE header. isakmp sa and an association wasnt built successfuly, Customers Also Viewed These Support Documents. The state displayed should be QM_IDLE for an IKE SA to be considered up and functioning. Refer to Configuring Router-to-Router IPSec (Pre-shared Keys) on GRE Tunnel with IOS Firewall and NAT for information on how to configure the basic Cisco IOS Firewall configuration on a GRE tunnel with Network Address Translation (NAT). Use the physical interface (or the loopback interface) IP addresses to identify Internet Key Exchange (IKE) peers. Note:Use the Command Lookup Tool (registered customers only) to find more information on the commands used in this document. )@\Opz3CL2k(&]pi~K% So, let's configure the GRE Tunnel. To test and verify this, all that is required is to ping the other end and force the VPN IPSec tunnel to come up and start encrypting/decrypting our data: Using the show crypto session command, we can quickly verify the encryption is in place and doing its work: Sending 5, 100-byte ICMP Echos to 172.16.0.2, timeout is 2 seconds: Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms. Hence, the tunnel does not have any IP address configured. Workstations on either network will still not be able to reach the other side unless a static route is placed on each endpoint: On R1 we add a static route to the remote network 192.168.2.0/24 via 172.16.0.2 which is the other end of our GRE Tunnel. These are RFC 1918 addresses which have been used in a lab environment. 64.100.13.2 209.165.118.1 QM_IDLE 1026 0 ACTIVE, 209.165.118.1 64.100.13.2 QM_IDLE 1062 0 ACTIVE, 209.165.118.1 64.102.46.2 QM_IDLE 1073 0 ACTIVE. endobj NOTE In the legacy configuration, the crypto map had the following commands: Set Transform-set: In the legacy configuration, this is done in the crypto ipsec profile. ( ~\%-O1&H89|R8G > =@} >tqCN.| 9|`-2(v!L>N2r"+KN%5CH hjHBAJD6H%wKj1wSL~9O?zp} wy 'K[{O _N!LQ.dq*"K\M0 a:l4Z#G!iZ`R*++9XZ&,Z:FIOhuQr~WboN7MjI`kcC9<63! ,8ynzRLRMaCL8vtJI5r.`,3l X#ox\4{Z9/}i17L \ @|#gakJez|YwPSw`>[4Y}LBZ,f[( @p18p6\c1g `>4|SWnFNcc]Kw72#]Kyb >#'&Qm368i.\W1%6_$KC7P5,Sr The information presented in this document was created from devices in a specific lab environment. Next, we must create the Tunnel 0 interface on R2: R2s Tunnel interface is configured with the appropriate tunnel source and destination IP address. ]Nz1Z |hDTgvkC =@}KWws}+ts_7Y;j1B Coming back to your question, regarding GRE inside IPSec, you should use gre as the protocol in the access list; that right, you shud get points for that !! By default, GRE does not perform any kind of encryption. I don't have packet-tracer to check your full configuration, you say you've got EIGRP configured on all routers, is the traffic being routed unencrypted? &0 gt>iC7y()\&'( X_\c/gpZ[1-A}]bNv fK+8X?ul@uS()} 93 z;S^_- "MCSnU9fmC; Step 2 - Specify the tunnel interface source. Both tunnels must be configured at your gateway. Because most transport MTUs are 1500 bytes and we have an added overhead because of GRE, we must reduce the MTU to account for the extra overhead. For this purpose, we use IPSec to add an encryption layer and secure the GRE tunnel. As mentioned earlier, GRE is an encapsulation protocol and does not perform any encryption. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. This document illustrates an IP Security (IPSec) configuration using a generic routing encapsulation (GRE) tunnel between two routers. endobj Let me show you a topology that we will use to demonstrate GRE: Above we have 3 routers connected to each other. I must have had a misconfigured netmask and crytpo map missplaced. <> Create a tunnel interface (the IP address of tunnel interface on both routers must be in the same subnet), and configure a tunnel source and tunnel destination under tunnel interface configuration, as shown: Use the OIT to view an analysis of show command output. R!UMA:N#p!0a+(G ,qIcT\t_=.fy wXh&''8dz+ ~8>j@ To configure a basic GRE tunnel: RouterA(config)# interface Tunnel0 RouterA(config-if)# ip address 1.1.1.1 255.0.0.0 RouterA(config-if)# tunnel source s0/0 RouterA(config-if)# tunnel destination 77.1.1.1 RouterB(config)# interface Tunnel0 RouterB(config-if)# ip address 1.1.1.2 255.0.0.0 RouterB(config-if)# tunnel source s0/0 RouterB(config-if . Ive attached the lab if someone wants to give it a try and help me solve this. The second tunnel acts as a backup tunnel. 7 0 obj 42bE7u-k`)) YeSFK mS' 34.w9 eHb4]lp$8X@a/rsgLhJLj3 ` %]o(%R~ns}=>>o#W}G>qG~@}o9=sNQPEY#::C D[X\C!t#RrU[GsU45/)G R [b1S1bHDwG w@Jm;X'Lrj5hV2d(#0q0gfE2>V8?vB This document explains how to configure an IPSec tunnel connection between the Mediant 1000 MSBG and a Cisco router. This section provides information you can use to troubleshoot your configuration. Refer to Configuring IPsec Router-to-Router Hub and Spoke with Communication Between the Spokes for information on how to configure a hub and spoke IPsec design between three routers. 3'lX{h} qcW._BU dfe{7z2+(0qNv/3\=ryeB]jlz{su@e46,!oXL+b"$aY\}^2j*sVbh0LnBia 5T`5up 54M*SrlgAhUZjM0A1/?~|L;.oBZe 2 0 obj `6]C` >F?Je49 Each Tunnel interface is assigned an IP address within the same network as the other Tunnel interfaces. Having the crypto map on the physical and tunnel interface when using the 12.2. All of the devices used in this document started with a cleared (default) configuration. Since GRE is an encapsulating protocol, we adjust the maximum transfer unit (mtu) to 1400 bytes and maximum segment size (mss) to 1360 bytes. The GRE tunnel in this example is purely used for transporting non-IP traffic. Basically when you configure a tunnel, it's like you create a point-to-point connection between the two devices. $MOw{h_sK600pldc/|*B;vt2r ._ endobj A GRE tunnel is used when packets need to be sent from one network to another over the Internet or an insecure network. XK"?H2. zJaBmvkUSR'|+E>QfCx'O u^iu%-=[kDR0nr%7 y}C_3E[|IPMqJ%Hy ##_04 ViEG]GO3_-U+"NOVa\05Y'S-Kt`%S>]IH}q(vZe#0VaIz-zt][:>#6pw#-t/kYB*FV#1|E)L`rw-=f$rP{U8u^XE}pZw*|*_Yv+vT^6k#;bjp}Mc9ml>{z[ULUDG9:q2 The crypto access control list (ACL) should have GRE as the permitted protocol. The key parameters in the output are indicated in bold. 10 0 obj show ip routeDisplays IP routing table entries. These steps are: IKE exists only to establish SAs (Security Association) for IPsec. For explanation on the command outputs, refer to the IP Security Troubleshooting - Understanding and Using debug Commands document. New here? pQ%'zwho_z]+h%NUZb~y;t`8AWE L5tP'z` show crypto engine connection activeShows each Phase 2 SA built and the amount of traffic sent. ")oTa1k}sCqXVW,Jq)8DIpQ7fdcR(W0J*Lyi`@^}`S/f@'i(E5c)g~ >o+gzW}#te'w`sO~O>zD&b4lyak}3Rc+1A|F9NQ%v}Hg B\b GU> S>| S>lJd~O;BZha7r8t{8\3 k,CehH`)R\ 5 0 obj With GRE, a virtual tunnel is created between the two endpoints (Cisco routers) and packets are sent through the GRE tunnel. If your network is live, make sure that you understand the potential impact of any command. This example uses generic routing encapsulation (GRE) in order to accomplish routing between the different networks. I cant really understand why. }I0WrRTmiWP <> show ipx interface Displays the status and parameters of the IPX interfaces configured on the device such as the IPX network and node address. In this lesson I will show you how to configure an encrypted GRE tunnel with IPSEC. RoutertoRouter IPSec (RSA Keys) on GRE Tunnel with RIP Configuration Example Document ID: 29780 Contents Introduction Prerequisites Requirements Components Used Conventions . The IPX ping command is executed on router1 destined for router2. Written by Administrator. Note:Crypto does not support the Cisco 7600 Series Router. West and East are using their own Loopback0 interface as the tunnel source, and the other's Loopback0 as the tunnel destination. Ensure that you meet these requirements before you attempt this configuration: Make sure that the tunnel works before you apply the crypto maps. As soon as we complete R1s configuration, the router will confirm the creation of the tunnel and inform about its status: Since the Tunnel 0 interface is a logical interface it will remain up even if there is no GRE tunnel configured or connected at the other end. "iii*-]')wAET0C'U)v^n\ECGdt?KolD?Nd;4I $U7q&6]Pq-^b2V00NrdBv^59 qNJ{hTqP]H4!vD\&+p0:V3e7~7x7z >g:{?7^~oKqbi^,2pO*VU, ~p0yF2~[b052Nt34&HN bJ$QwKDB 3gp48X8,Zz4 6YrS^/!Q# enTypSnPh*?znHS\*YLRT? Weve named our IPSec profile protect-gre: We are ready to apply the IPSec encryption to the Tunnel interface: Now it's time to apply the same configuration on R2: Finally, our tunnel has been encrypted with IPSec, providing us with the much needed security layer. Before attempting this configuration, please ensure that you meet the following prerequisites: knowledge of IPX configuration and routing, knowledge and configuration of GRE tunnels, working knowledge and configuration of IPSec. If data protection is required, IPSec must be configured to provide data confidentiality this is when a GRE tunnel is transformed into a secure VPN GRE tunnel. This document uses the configurations shown below. GRE usages IP protocol number 47. <> I HEa?3#& rEmmkPoG5k6>wAW v The tunnel protection ipsec profile command states that any traffic that traverses the tunnel should be encrypted with the IPSec profile called ABC. endstream In this section, you are presented with the information used to configure the features described in this document. In our example, both Tunnel interfaces are part of the 172.16.0.0/24 network. View with Adobe Reader on a variety of devices, PIX/ASA 7.x and later : VPN/IPsec with OSPF Configuration Example, Configuring IPsec Router-to-Router Hub and Spoke with Communication Between the Spokes, Configuring Router-to-Router IPSec (Pre-shared Keys) on GRE Tunnel with IOS Firewall and NAT, Adjusting IP MTU, TCP MSS, and PMTUD on Windows and Sun Systems, Troubleshooting the PIX to Pass Data Traffic on an Established IPSec Tunnel, Cisco Secure PIX Firewall Command References, Technical Support & Documentation - Cisco Systems. This article will explain how to create simple (unprotected) and secure (IPSec encrypted) GRE tunnels between endpoints. (J#9-*htZ3>4N#(d%3 ,Z X&;.LDRd,1Nu[g,hgY interface tunnel 0 ip address 192.168..1 255.255.255.252 tunnel source serial 0/0/0 tunnel destination 64.100.13.2 tunnel mode . show ipx route Displays the contents of the IPX routing table. b979 Ih4J&9a4$''FOcfJc*%3NAQZ+Zg`4U%=B]m?e%(Z-k) |la~>/pP8-v/hV.Ad_hX>\ |AO!y^H#mW?19=V G:M <]/Interpolate true/Width 575/BitsPerComponent 8/Length 21495/Height 171/Filter/FlateDecode>>stream If you are working in a live network, ensure that you understand the potential impact of any command before using it. When R1 receives a packet for 192.168.2.0 network, it now knows the next hop is 172.16.0.2 and therefore will send it through the tunnel. The outputs on Router2 are similar. 3 0 obj <> IPSec can be used to encrypt GRE tunnels to provide network layer security for non-IP traffic, such as Novell Internetwork Packet Exchange (IPX), AppleTalk, and so forth. 4 0 obj This section provides information you can use to troubleshoot your configuration. We explain all the necessary steps to create and verify the GRE tunnel (unprotected and protected) and configure routing between the two networks. flx +`fl9>HP2q"%bENOOOp:1r rI#eM]"XZj9 57;38H++v8uNK5j[5cMJe1? GRE IPSec modes are covered extensively in our GRE and IPSec GRE Over IPSec - Selecting and Configuring Gre IPSec Tunnel or Transport Mode. 2022 Cisco and/or its affiliates. debug crypto engine Shows information about the crypto engine performing encryption and decryption process. This section provides information you can use to confirm your configuration is working properly. 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