I recently bought a 4 bay synology NAS (DS416 Play). The main issue I had was off-site backups. It’s ok having 4 disks for resilience, but if my house burns down or gets burgled, I still lose everything. So I started to think up ways of doing an offsite backup, without having to remember to …
Off-site backups for Synology NAS – using two raspberry pi’s, behind dynamic NAT IP’s Read More »
A few days ago I stumbled upon the python interpreter on the Nexus platform. It got me to tinkering. In the past, I have had a requirement to grab a list of all of the interfaces on a box, the IP’s, and the masks. The interfaces and IP’s can easily be obtained from a show …
A number of times in the last few weeks I have been asked by a number of people: What is ARP? There is the simple answer – which is simply a definition: Address Resolution Protocol (ARP) is a mechanism to resolve IP addresses into MAC addresses. However…that doesn’t really explain a lot. It probably doesn’t …
While troubleshooting a totally unrelated issue, one of my colleagues noticed that they were seeing packets in a tcpdump that were neither destined for nor sourced from the server. This is odd, when plugged into a switch, so we started digging. Server 1, was sending a stream of packets to Server 2 – in a …
Why am I seeing packets on my server that aren’t for this server? Read More »
It’s been a mad couple of weeks with Nexus 7000’s. My client hit a software bug on their Nexus 7k, which turned out to be a most impressive bug. It basically causes the flash drives to be erroneously marked as faulty, which then causes them to be remounted in read only. The first symptom was …
Nexus 7000 Software Bug – Flash RAID Errors – 7k Reboot and Failover Read More »
Recently we had a Cisco Web Security Appliance (WSA) Proxy fail. When I say fail, I mean a single stick of RAM failed after a reboot. Cisco said RAM isn’t replaceable so we had to RMA the whole box (odd for a device that is basically a rebadged server…maybe I have a money saving idea …
Replacing a failed Cisco Ironport Web Security Appliance Proxy Read More »
While going over some OSPF stuff today, I found a statement saying that OSPF network types have to match for routers for form a neighbour relationship. Because I’m a nerd, I questioned this. My reason? I don’t remember OSPF network type being a field in the hello packet header. And if it’s not in the …
I encountered an issue recently while trying to allow access to a new subnet over an existing VPN. The far end device was a Cisco router, and had an access list matching an entire class A subnet which was applied to the crypto map. The traffic destined for the new subnet was arriving at our …
Checkpoint VPN Error: According to the policy the packet should not have been decrypted Read More »
I recently had the need to upgrade the IOS on a Cisco switch (think it was a 3750). As usual, the flash was too small so I needed to remove (and archive/save) the old IOS before putting the new one on. A lot of the images these days include HTML and other things, so are …
In my job I quite often find myself with a whole bunch of host names that I need IP’s for. I found it quite repetitive to keep opening a command prompt and typing “nslookup hostname”, then copying and pasting it somewhere. So I started googling. I have never used Powershell before, so this was a …
Bulk DNS Lookup in Windows Powershell – Better than NSLookup! Read More »
