Category: Cisco
-
Cisco ASA SSH, Don’t Forget To Generate A Key
If you are just now enabling SSH and you get the following error message: SSH session from XXX.XXX.XXX.XXX on interface Outside for user "" disconnected by SSH server, reason "Internal error" (0x00) It looks like you need to generate an RSA key for SSH: crypto key generate rsa modulus 1024
-
Cisco 6500/7600 In Service IOS Upgrades
If you have redundant processors, why not take advantage of it. You can upgrade the IOS on the redundant processor, fail over to it, then do the same to the primary. In theory you will see no outtage. Cisco’s link.
-
Cisco 7600 Or 6500 Boots To Rommon
If you boot straight to rommon on your 7600, with a message saying that it is unable to find boot file: Autoboot: failed, BOOT string is empty Then first check the boot flash on the supervisor: rommon 1 > dir bootflash: You will most likely see something along the lines of : rommon 1 >…
-
Second Line On Cisco ATA 186/188
Cisco ATAs have a second line, but you may have also noticed that there is no phone button template that includes two lines for an ATA 186…interesting. It turns out that the second line on the ATA has a completely seperate MAC address associated with it. To use the second line you add it as…
-
Block RFC-1918 Spoofed Traffic
A general rule of thumb in a service provider network is to block RFC-1918(private addressing) address space. You want to block this incoming from your upstream providers also, but generally filtering it in your network is a good idea. You will also want to block any traffic coming from your provider sourced from your address…
-
Cisco – Troubleshoot POS Interface
Troubleshooting a POS(Packet Over Sonet) interface is quite different than your standard ethernet interface. The first thing you will obviously do is a: show interface POS1/0/0 If you are down/down then you obviously aren’t seeing light across the link and you need to troubleshoot accordingly. If you see the link as up/down, then you are…
-
Manipulating OSPF Path Selection With Cost
My good friend JJ asked me a question the other day about OSPF path selection. It was something like “I have a redundant network and I want to adjust cost on an individual route…how do I do that?” Seems pretty straight forward, right?…not exactly. Cost is the metric OSPF uses to judge a path’s feasibility.…