This configuration uses CLI commands. GRE (Generic Routing Encapsulation) is a simple tunneling technique that can do this for us. Note:Before issuing debug commands, please see Important Information on Debug Commands. 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. \81hf&vtD@,_k fYk8||ckz4WknDjv Wm\Ku|N?h_O&#H}:lj2 4!Lk_` show crypto engine connection activeShows each Phase 2 SA built and the amount of traffic sent. In order to configure the GRE tunnel, you must need connectivity between two remote routers through static Public IP address. 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. 2022 Cisco and/or its affiliates. With GRE, a virtual tunnel is created between the two endpoints (Cisco routers) and packets are sent through the GRE tunnel. Note:Refer to Important Information on Debug Commands before you use debug commands. IPSec VPN tunnels can also be configured using GRE (Generic Routing Encapsulation) Tunnels with IPSec. If your network is live, make sure that you understand the potential impact of any command. mS' 34.w9 eHb4]lp$8X@a/rsgLhJLj3 ` <> 2 0 obj In software versions prior to this release, IPSec crypto maps need to be applied to both the tunnel interface and the physical interface. ( ~\%-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[( There is currently no verification procedure available for this configuration. For this purpose, we use IPSec to add an encryption layer and secure the GRE tunnel. The outputs on Router2 are similar. These are RFC 1918 addresses which have been used in a lab environment. 11 0 obj This section captures the debug command outputs on the routers configured with IPSec. With GRE, a virtual tunnel is created between the two endpoints (Cisco routers) and packets . West and East are using their own Loopback0 interface as the tunnel source, and the other's Loopback0 as the tunnel destination. The documentation set for this product strives to use bias-free language. GRE IPSec modes are covered extensively in our GRE and IPSec GRE Over IPSec - Selecting and Configuring Gre IPSec Tunnel or Transport Mode. 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). endobj <> 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). In our example, both Tunnel interfaces are part of the 172.16.0.0/24 network. 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). The Output Interpreter Tool (registered customers only) (OIT) supports certain show commands. >{3*zGb]>bCqz{M]g[^A*kr}l~4ba4W{8GXB#}YXSfarz # eMww`l5683"UG1Fv$,18uORzmgu_GA Let me show you a topology that we will use to demonstrate GRE: Above we have 3 routers connected to each other. 10.31.4.52 a 10.31.4 . Also remember that the ip address given as tunnel destination should be globally routeable. I'm trying to build a GRE Tunnel with IPSec encryption (I may be phrasing this incorrectly, I realize). Basically when you configure a tunnel, it's like you create a point-to-point connection between the two devices. ;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. We explain all the necessary steps to create and verify the GRE tunnel (unprotected and protected) and configure routing between the two networks. Weve named this TS: Finally, we create an IPSec profile to connect the previously defined ISAKMP and IPSec configuration together. This document illustrates an IP Security (IPSec) configuration using a generic routing encapsulation (GRE) tunnel between two routers. If you are working in a live network, ensure that you understand the potential impact of any command before using it. %]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 The IPX ping command is executed on router1 destined for router2. For explanation on the command outputs, refer to the IP Security Troubleshooting - Understanding and Using debug Commands document. isakmp sa and an association wasnt built successfuly, Customers Also Viewed These Support Documents. 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. 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. The second tunnel acts as a backup tunnel. Prerequisites Requirements Ensure that you meet these requirements before you attempt this configuration: <> 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. 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. 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. Configure In this section, you are presented with the information to configure the features described in this document. 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. This document illustrates how to route between different networks that use a routing protocol and non-IP traffic with IPsec. 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 This is the topology that we will use: Above we have 3 routers. You may have to install the VPN module in order for this to work. Learn more about how Cisco is using Inclusive Language. Make sure that the GRE tunnel works before applying the crypto maps. &0 gt>iC7y()\&'( X_\c/gpZ[1-A}]bNv fK+8X?ul@uS()} 93 z;S^_- "MCSnU9fmC; 6 0 obj Posted in Cisco Routers - Configuring Cisco Routers. Refer to Troubleshooting the PIX to Pass Data Traffic on an Established IPSec Tunnel for additional information on troubleshooting a PIX and IPsec tunnel. $MOw{h_sK600pldc/|*B;vt2r ._ The tunnel protection ipsec profile command states that any traffic that traverses the tunnel should be encrypted with the IPSec profile called ABC. As mentioned earlier, GRE is an encapsulation protocol and does not perform any encryption. endobj The HQ and Branch router each have a loopback interface that will represent their LAN connection. "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# 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 . A!dlD6&r!x]3M 3'lX{h} qcW._BU dfe{7z2+(0qNv/3\=ryeB]jlz{su@e46,!oXL+b"$aY\}^2j*sVbh0LnBia 5T`5up 54M*SrlgAhUZjM0A1/?~|L;.oBZe debug crypto engine Shows information about the crypto engine performing encryption and decryption process. This results in two GRE + IPsec packets of 1500 (1476 + 24 = 1500) and 68 (44 + 24) bytes each. 5 0 obj I must have had a misconfigured netmask and crytpo map missplaced. IPSec Transport mode is not used by default configuration and must . '2I?hGQcYZE 7e6?O _nbWOwwRYQg]v8& ,4|oX=h^ Ct[0l%HnF This section provides information you can use to troubleshoot your configuration. `6]C` >F?Je49 The entire GRE payload will be encrypted using the same IPSec link. )R4 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. <> 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.). Note:Use the Command Lookup Tool (registered customers only) to find more information on the commands used in this document. 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. Before it can do this, IKE must negotiate an SA (an ISAKMP SA) relationship with the peer. 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. Ive checked configurations but I must be missing something. endobj show ipx route Displays the contents of the IPX routing table. 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. Part Two - Configuring the GRE tunnel on the Cisco router Step 1 - Enter configuration mode. RoutertoRouter IPSec (RSA Keys) on GRE Tunnel with RIP Configuration Example Document ID: 29780 Contents Introduction Prerequisites Requirements Components Used Conventions . endstream All of the devices used in this document started with a cleared (default) configuration. 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. 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. 1 0 obj (because the ip packet is first encapsulated by GRE and then AH/ESP headers are added). Again the "show crypto ipsec sa" would confirm the traffic selectors, provide the output for further review. This document uses the network setup shown in the diagram below. 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. 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. R!UMA:N#p!0a+(G ,qIcT\t_=.fy wXh&''8dz+ ~8>j@ <> In large networks where routing protocols such as OSPF, EIGRP are necessary, GRE tunnels are your best bet. The information in this document is based on the software and hardware versions below. Both routers are connected to "the Internet" using the ISP 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. Note:The IP addressing schemes used in this configuration are not legally routable on the Internet. IPSec encryption involves two steps for each router. This section describes how to configure two IPSec VPN tunnels on Cisco 881 ISR running Cisco IOS 15.0. A major difference is that GRE tunnels allow multicast packets to traverse the tunnel whereas IPSec VPN does not support multicast packets. (13)T software and later should still work; however, Cisco highly recommends that you apply it just on the physical interface. 42bE7u-k`)) YeSFK Refer to Cisco Technical Tips Conventions for more information on document conventions. Ide appreciate any help on understanding whats happening and why. %PDF-1.2 An icmp echo from one end will confirm this: Again, this result means that the two tunnel endpoints can see each other. In this section, you are presented with the information used to configure the features described in this document. 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. (J#9-*htZ3>4N#(d%3 ,Z X&;.LDRd,1Nu[g,hgY By default, GRE does not perform any kind of encryption. Since GRE is an encapsulating protocol, we adjust the maximum transfer unit (mtu) to 1400 bytes and maximum segment size (mss) to 1360 bytes. 2022 Cisco and/or its affiliates. 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. 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 . Next, we must create the Tunnel 0 interface on R2: R2s Tunnel interface is configured with the appropriate tunnel source and destination IP address. 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 . Refer to Configuring IPsec RoutertoRouter Hub and Spoke with Communication Between the Spokes for RoutertoRouter IPSec (RSA Keys) on GRE Tunnel with RIP Configuration Example Document ID: 29780 Contents Introduction Prerequisites Requirements Components Used Conventions . This section captures the show command outputs on the device Router1 when the IPX ping command is executed on Router1 destined for Router2. The information in this document was created from the devices in a specific lab environment. 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 Each Tunnel interface is assigned an IP address within the same network as the other Tunnel interfaces. 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-/ ! jLky endobj 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. Turn off fast switching on the tunnel interface. Learn more about how Cisco is using Inclusive Language. }I0WrRTmiWP This provides us with the necessary military-grade encryption and peace of mind. !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/. refer to Cisco Technical Tips Conventions. The information presented in this document was created from devices in a specific lab environment. I HEa?3#& rEmmkPoG5k6>wAW v For this reason, plus the fact that GRE tunnels are much easier to configure, engineers prefer to use GRE rather than IPSec VPN. This article will explain how to create simple (unprotected) and secure (IPSec encrypted) GRE tunnels between endpoints. 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. `>j 7u]O~g4c]WddiMIb0KH)t;lN)z]\QsB5JF(z/Bp Ensure that you meet these requirements before you attempt this configuration: Make sure that the tunnel works before you apply the crypto maps. 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: Written by Administrator. Use the physical interface (or the loopback interface) IP addresses to identify Internet Key Exchange (IKE) peers. In this lesson I will show you how to configure an encrypted GRE tunnel with IPSEC. Now we need to create the transform set used to protect our data. 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. GRE tunnels greatly simply the configuration and administration of VPN tunnels and are covered in our Configuring Point-to-Point GRE VPN Tunnels article. Hence, the tunnel does not have any IP address configured. Step 2 - Specify the tunnel interface source. This document uses the configurations shown below. show crypto map Displays the crypto maps configured on the router along with its details such as crypto access lists, transform sets, peers etc. This document explains how to configure an IPSec tunnel connection between the Mediant 1000 MSBG and a Cisco router. View with Adobe Reader on a variety of devices, IP Security Troubleshooting - Understanding and Using debug Commands, IP Security (IPSec) Technology Support Page. enTypSnPh*?znHS\*YLRT? Ive attached the lab if someone wants to give it a try and help me solve this. Hence, the tunnel does not have any IP address configured. ."S,`IVOeew,tCB`osg!Xw ;=. Having the crypto map on the physical and tunnel interface when using the 12.2. 8 0 obj Refer to Cisco Technical Tips Conventions for more information on document conventions. show crypto ipsec sa Shows the phase 2 security associations by displaying a detailed list of the router's active IPSec SAs. flx +`fl9>HP2q"%bENOOOp:1r rI#eM]"XZj9 57;38H++v8uNK5j[5cMJe1? % GRE IPSec Transport Mode. <> These steps are: IKE exists only to establish SAs (Security Association) for IPsec. All of the devices used in this document started with a cleared (default) configuration. All rights reserved. 3 0 obj show ipx interface Displays the status and parameters of the IPX interfaces configured on the device such as the IPX network and node address. 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. 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\[]! ]Nz1Z |hDTgvkC =@}KWws}+ts_7Y;j1B endobj So, let's configure the GRE Tunnel. Only a single tunnel is operational at any time. Use the OIT to view an analysis of show command output. 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). 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$rP{U8u^XE}pZw*|*_Yv+vT^6k#;bjp}Mc9ml>{z[ULUDG9:q2 }H5IU~agRmLg|2!IGXsPHb79 w)D"5sT6;P:', bI0KV]MA0GDat*4Omcr\NCoeffF 4 0 obj XK"?H2. zJaBmvkUSR'|+E>QfCx'O u^iu%-=[kDR0nr%7 ujIURI;o\'x=kT/^HhoKpB8xZHAn60;756p|9Ek6Y\lUdY%T2nl+zS!V\v346/^&MT{ku6vQ\=51-5SNMJSe4@0q*:cHBdN*k#C/Ig($ q#I*! This effectively exposes the GRE IP Header as it is not encrypted the same way it is in Tunnel mode. The main drawback of GRE protocol is the lack of built-in security. 9 0 obj 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. FoEsgUj4_6B*w=w|r|!`MIT*Cr*RTT.yp^(NRiG,6m%Z`T3)uzvG^`UA5{Wy0=CmH,Q'v{M Our example below covers GRE IPSec Tunnel mode. The same configuration must be repeated for R2: Now both networks are able to freely communicate with each over the GRE Tunnel. 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. 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 In this section, you are presented with the information to configure the features described in this document. GRE encapsulates the IP fragments, which adds 24 bytes to each packet. This example uses generic routing encapsulation (GRE) in order to accomplish routing between the different networks. @p18p6\c1g `>4|SWnFNcc]Kw72#]Kyb >#'&Qm368i.\W1%6_$KC7P5,Sr 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 !! 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. debug crypto ipsec View the IPSec negotiations of phase 2. debug crypto isakmp View the IKE negotiations of phase 1. Note:Crypto does not support the Cisco 7600 Series Router. The connection is encrypted with the industry- . 7 0 obj 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 endobj 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. Both tunnels must be configured at your gateway. 10 0 obj The crypto access control list (ACL) should have GRE as the permitted protocol. show crypto isakmp sa Shows the phase 1 security associations by displaying the router's IKE SA. Z) f4j0J#R8% )/sO}yA6lhtb/O?xzSO"$>.{2N; This section provides information you can use to troubleshoot your configuration. endobj A GRE tunnel is used when packets need to be sent from one network to another over the Internet or an insecure network. Note:To find additional information on the commands used in this document, use the Command Lookup Tool (registered customers only) . New here? 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. 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. )@\Opz3CL2k(&]pi~K% A setting of 1400 is a common practice and will ensure unnecessary packet fragmentation is kept to a minimum. NFrt<2tdc% <>stream 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. 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. 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. 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. 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). I now can ping from PC0. This section provides information you can use to confirm your configuration is working properly. 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. I cant really understand why. The documentation set for this product strives to use bias-free language. <> Yf`lx- k[r endobj 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. 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, ( v^Gip~>['ytJ_7{@?/?58QBP@rhiBZOFD1J)9vU+SP(3&u. <> show ip routeDisplays IP routing table entries. Configure In this section, you are presented with the information to configure the features described in this document. endobj The GRE tunnel in this example is purely used for transporting non-IP traffic. refer to Cisco Technical Tips Conventions. The state displayed should be QM_IDLE for an IKE SA to be considered up and functioning. 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. To configure Generic Routing Encapsulation (GRE) over an IPSec tunnel between two routers, you can refer to these steps as follows: 1. GRE usages IP protocol number 47. 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. This key will be used for allISAKMP negotiations with peer 2.2.2.10 (R2). 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. <]/Interpolate true/Width 575/BitsPerComponent 8/Length 21495/Height 171/Filter/FlateDecode>>stream 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. show crypto engine connections active Displays a list of active SAs with their associated interfaces, transforms and counters. Refer to Adjusting IP MTU, TCP MSS, and PMTUD on Windows and Sun Systems for information about possible Maximum Transmission Unit (MTU) issues. endobj The previous tutorial shown GRE tunnel configuration between Cisco router and Linux Core. 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. <> The key parameters in the output are indicated in bold. 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. Closing, we define the Tunnel source, which is R1s public IP address, and destination R2s public IP address. The GRE tunnel in this example is purely used for transporting non-IP traffic. 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. 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 All rights reserved. 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. ")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\ Although, you can configure the GRE Tunnel over the IPSec VPN for securing the GRE tunnel. You can view the bug details for this issue at CSCdm10376 (registered customers only) . Certain show commands are supported by the Output Interpreter Tool (registered customers only) , which allows you to view an analysis of show command output. pQ%'zwho_z]+h%NUZb~y;t`8AWE L5tP'z` 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? I also checkedisakmp sa and an association wasnt built successfuly between R3 and R0 even though it was using the tunnel (very odd). ,}Q#-gyiH0ls 'J&V^dE)2M)/3F&\(b&rfQmuucR=nb~n~s(T4TC8V0r 1&1McB6H1t/G;LBG3ZN8t4-'WL_^>|r O|T_o=_Gyo~gk^`(:? 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