May 072008

I dont think we need an introduction to the most widely used Remote console utility, PUTTY. Putty support SSH, Telnet, RLogin & RAW connections.

If you telnet or SSH to your Cisco IOS routers or switches or Juniper Firewalls and ofcourse anything that support CLI and SSH or Telnet then one of the things you would prefer to do is to take a backup of the config (Running or Startup) or even capture session text including logs tech information etc. We discussed here about using Hypereterminal to capture text and hence backup and restore config on Cisco IOS Routers and Switches.

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Feb 202008

If you have site to site IPSec VPNs configured between two network with your Juniper Netscreen or SSG firewalls and clients from one network access servers or services from the other network then it is advisable to enable Path MTU Discovery support on the Juniper firewalls.

Juniper Netscreen or SSG firewalls running Screen OS by default disable the Path MTU Discovery support. This means, when an IP Packet with DF bit set ("1") in the ip Header and its size after IPSec Encapsulation is more the MTU of the Juniper VPN Firewall arrives at the VPN Firewall, the firewall will ignore the "DF" bit and simply fragments the packets and forwards it to the appropriate tunnel interface. This can cause serious problems with some applications. A classic example is the Microsoft Applications that rely on NetBIOS over TCP/IP which wouldn't prefer the packets being fragmented (and hence DF set).

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Sep 112007

Nipper is an Opensource tool for network device congiguration and security audit. Nipper performs security audits of network device configuration files. The report produced by Nipper includes; detailed security-related issues with recommendations, a configuration report and various appendices. Continue reading »