Cisco VPN Client Connects but no traffic will Pass
Note: May also be asked as, Client VPN connects but cannot ping anything behind the Firewall. KB ID 0000199 Problem If I had a pound for every time I’ve seen this either in the wild, or asked in a forum, I would be minted! In nearly every case the problem is NAT related. In most cases, If the person launching the VPN client is behind a device that is performing NAT, (Home Router, Access Point, Firewall, etc) then the device will...
Cisco Stacking 3750 Switches
KB ID 0001205 Problem You can stack Cisco 3750-X Switches in groups of up to 9 switches, and they can then be managed as one switch. Here I’ve got 2 switches. Solution Removing 3750-X Switches Stack Configuration One of my switches had already been in a stack, so I needed to remove its stack configuration. It thought it was switch 4 in the stack so I issued the following commands; Switch(config)# no switch 4 provision...
Cisco – Testing AAA Authentication (Cisco ASA and IOS)
KB ID 0001175 Problem I always forget the syntax for this, and I’ve been meaning to publish this for a while so here you go. If you have AAA setup and people can’t log in, then the ability to test authentication against a user’s username and password is a good troubleshooting step! Usually I’m on a Cisco ASA but I’ll tag on the syntax for IOS as well. Solution Cisco ASA Test AAA Authentication From...
Cisco IOS – DHCP Helper (DHCP Relay) – IP-Helper Setup
KB ID 0001168 Problem Cisco documentation calls this a ‘DHCP Relay’, and uses the command IP-Helper, and I usually call this DHCP Helper, just to confuse everyone. To be fair the term DHCP Relay is an industry standard, it’s not particular to Cisco (as you will see later when I Wireshark the traffic). So If you are reading this you have a DHCP server and you want to use it to lease addresses to clients that are on a...
Cisco Small Business (SG500) Link Aggregation (LAG) With LACP
KB ID 0001277 Problem At work a client was having trouble with a NAS Drive (Buffalo Terastation). It was being used as a backup target and some of the servers were dropping connections. I knew the client had some Catalist 3750’s So I suggested going and creating an Ether Channel to the two NICs in the NAS box, to try and cure the problem. However when I went onsite, I noticed the 3750 didn’t have any spare Gigabit ports...