topic Re: GRE thru pix in Network Security https://community.cisco.com/t5/network-security/gre-thru-pix/m-p/377726#M553880 <HTML><HEAD></HEAD><BODY><P>GRE is protocol number 47. It is not a TCP or UDP based protocol so it therefore does not have layer 4 (port) information. The PIX will recognize the name 'gre' in any access-list entry. An example would be:</P><P></P><P>access-list 101 permit gre host 1.2.3.4 host 5.6.7.8</P><P></P><P>Hope this helps.</P><P></P><P>Scott</P></BODY></HTML> Mon, 13 Dec 2004 17:59:58 GMT scoclayton 2004-12-13T17:59:58Z GRE thru pix https://community.cisco.com/t5/network-security/gre-thru-pix/m-p/377725#M553879 <P>what ports and protocols should be enabled on a pix to allow a gre tunnel between company a and company b internal routers across the internet?</P> Fri, 21 Feb 2020 07:48:12 GMT https://community.cisco.com/t5/network-security/gre-thru-pix/m-p/377725#M553879 rnutter 2020-02-21T07:48:12Z Re: GRE thru pix https://community.cisco.com/t5/network-security/gre-thru-pix/m-p/377726#M553880 <HTML><HEAD></HEAD><BODY><P>GRE is protocol number 47. It is not a TCP or UDP based protocol so it therefore does not have layer 4 (port) information. The PIX will recognize the name 'gre' in any access-list entry. An example would be:</P><P></P><P>access-list 101 permit gre host 1.2.3.4 host 5.6.7.8</P><P></P><P>Hope this helps.</P><P></P><P>Scott</P></BODY></HTML> Mon, 13 Dec 2004 17:59:58 GMT https://community.cisco.com/t5/network-security/gre-thru-pix/m-p/377726#M553880 scoclayton 2004-12-13T17:59:58Z