Too Many TCP Resets

So, recently we enforced some firewall rules on a new environment, we did testing of the environment and everything was working as expected. In about 24 hours a lot of traffic from the web infrastructure was being denied and it continued, at first glance it looked like return traffic was being dropped, the web servers were sourcing at port 443 and the destination ports were using dynamic ports (RFC 6335)

No user or application problems were reported when we enforced rules, and we waited additional days to see if anything came up. Nothing came up, the only thing was a spike in amount of syslog messages of dropped traffic coming from the web servers. So from that point it really wasn’t an issue, but I thought it would be interesting to see what was going on. Continue reading

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ASA Site to Site VPN (DHCP)

If you don’t already know, site to site VPNs can be a cost-effective way for remote sites to connect to HQ resources instead of a lease line like using MPLS or Metro-E circuits. We can instead use a standard internet connection with a static IP, this is usually cheaper than a dedicated circuit. Our next steps are purchasing a firewall for the remote site (assuming you already have one at HQ) and setup a site to site VPN connection to make the connection. Continue reading

Types of WAN Links

I’ve found this table that I created a while ago and it lists common WAN connections that businesses use. I have used this table like a reference guide to familiar myself into other protocols. People don’t think of it much but the WAN is a different beast compared the LAN as it uses different protocols besides Ethernet. The WAN or wide area network is what connects us to remote locations within a organization. If we have an office in New York and another office in Wyoming  we need these offices to be connected to each other so that they seem to be on the same network even though they are miles away these types of WAN connections and protocols  would do it. Continue reading

Distance Vector Routing

Couple weeks ago I talked about routing protocols and in the post I mentioned two routing protocol features distance vector and link state. Although these protocols fundamentally do the same thing by getting information on remote networks they get this information in a different way. For today let’s introduce distance vector routing. Continue reading

World IPv6 Day!!

Are we ready for IPv6?So what is IPv6 day? Today major companies like Google, Facebook, Yahoo and ISPs (Internet Service Providers) test their IPv6 deployments. Why is this important? Well if you follow IPv4 news you might already know that IPv4 addresses have been exhausted and the need to move to different address space is critical, if new web services are to be deployed. The question is can we run both? Continue reading