Using curl for troubleshooting

View only response headers

curl -I only retrieves the header of the resource. The ‘I’ is case sensitive.

root@ubnsrv01:/etc/ssl/certs# curl -I https://site3.lab.com
HTTP/1.1 200 OK
Content-Length: 191
Content-Type: text/html
Last-Modified: Thu, 17 Aug 2017 21:14:18 GMT
Accept-Ranges: bytes
ETag: "40d9a1c99d17d31:0"
Server: Microsoft-IIS/7.5
Date: Sat, 02 Sep 2017 22:58:54 GMT

View response headers and content

curl -i includes the HTTP header in the output along with the site content. Since this URL is terminating on an F5, the HTTP header reports that a redirect is configured for this URL but doesn’t redirect it automatically to the URL. The ‘i’ is case sensitive.

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Query refused for recursive DNS lookup in Infoblox

I recently configured my lab DNS infoblox server in a grid and setup some authoritative forward-mapping zones on it for my lab web-servers;

The DNS queries for the authoritative zones were working fine;

I then configured the DNS grid with 8.8.8.8 as a forwarder;

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How to setup and configure Infoblox vNIOS in EVE-NG

  1. Place the Infoblox DDI KVM image in the below path in EVE-NG.
/opt/unetlab/addons/qemu/linux-vInfoBlox-NIOS-8.1.2
  1. Fix permissions
/opt/unetlab/wrappers/unl_wrapper -a fixpermissions
  1. Open a new lab and add the linux-vInfoBlox-NIOS-8.1.2 node in EVE-NG and assign resources:
1 vCPU, 1536 Memory and 4 interfaces
  1. Start the node. Default username/password is admin/infoblox.

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Dynamic Multipoint VPN (CCIE Notes)

Disclaimer: These are my rough cut notes for CCIE Security studies! Not a detailed explanation of DMVPN.

Three components that make up DMVPN:

1. Mulitpoint GRE (mGRE)

  • Tunnel interface having multiple tunnel destinations unlike a point-to-point GRE tunnel that has a single tunnel destination.

2. Next-Hop Resolution Protocol (NHRP)

  • Each router in an NHRP topology acts as either a NHC or a NHS.
  • mGRE uses NHRP for mapping logical/tunnel IP address to physical/real IP addresses.
  • NHC registers its physical-to-tunnel mapped IP address to the NHS and the NHS acts as a database agent which stores all registered mappings and replying to NHC queries.
  • If a NHS does not have a requested entry in its database, it can forward packet to another NHS to see if it has the requested association.

3. Cisco Express Forwarding (CEF)

  • Cisco Express Forwarding (CEF) is a packet-switching technique which provides the ability to switch packets through a device in a very quick efficient way while also keeping the load on the router’s processor low.
  • CEF is made up of two different main components: the Forwarding Information Base (FIB) and the CEF Adjacency Table.

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