Hi, [please set me on Cc: since I am not on linux-kernel] we reproduce random kernel crashes with CentOS5 or RHEL5 kernels (2.6.18-x). ESP_input produces an error (see attachment). We set up VPN connections to netscreen firewalls or the Cisco PIX, the crashes occurs only after some time (20min up to 3days!), so it is not easy to reproduce. I attach a stacktrace (this one was captured in a VM, but it also happens on physical machines). We assume it is a bug in 2.6.18, I haven't check if it is fixed in newer versions. Can anyone help us? Dirk