11-16-2005 10:52 AM - edited 03-03-2019 10:59 AM
Hi,
How do I permit GRE traffic to be redirected to an internal host ? I already add port 1723 redirection.
I have a 1841 router with IOS version 12.
11-16-2005 11:35 AM
I am not sure that I understand the question. GRE packets are IP packets, they use GRE IP protocol type (protocol 47) instead of TCP or UDP IP protocols so they do not have the same type of port numbers.
If you can explain a bit more clearly what you are asking perhaps we can find a better answer.
HTH
Rick
11-16-2005 12:31 PM
What I want to do is to have a client on the Internet to connect to a Microsoft PPTP server through the 1841 router.
MS documentation says they use TCP port 1743 and GRE.
I already redirected the TCP 1743 port to the internal PPTP server. What steps are needed to redirect GRE to this host ?
11-21-2005 08:13 AM
Same process, but be sure (as Rick mentioned above) to specify protocol 47, not TCP or UDP. For instance
access-list 101 permit 47 any any
Regards
Jonathan Wilson
11-21-2005 08:25 AM
When I try to apply this access list to the outside interface I loose Internet browsing.
Can I use ACL even though I use NAT ?
02-24-2006 08:08 AM
Dd you get this working? Im also trying to do something similar, as Proto 47 GRE is portless how do I get it through NAT?
Basically if it were IPSEC we use UDP4500 to encasulate the ESP but I dont see how this can be done with GRE?
Anyone?
02-24-2006 08:57 AM
I had exactly the same requirement. Here is a configuration that works. These are only the relevant bits of the config to this question. Some of the outbound acl entries are redundant as it has permit ip any in the bottom, but you get the picture anyway.
interface Dialer1
ip access-group INBOUND in
ip access-group OUTBOUND out
ip nat inside source list NAT_LIST interface Dialer1 overload
ip nat inside source static 10.1.1.1
ip access-list extended INBOUND
evaluate MY_REFLECT
permit gre host
permit tcp host
ip access-list extended OUTBOUND
permit tcp any any reflect MY_REFLECT
permit udp any any reflect MY_REFLECT
permit icmp any any reflect MY_REFLECT
permit ip any any reflect MY_REFLECT
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