Installing and Using Telnet Service for Windows NT

[Ed. Note: This is a wee bit dated. SSH is widely available for Windows now, and should be used instead of telnet for administration. Still, telnet can be handy for testing. For an updated version of this for Windows 2000, see this article.] We wrote a tip about using IIS and rconsole to remotely manage […]

Remote Console Server and Web Administration Tool for NT

Two very useful remote administration tools are the Remote Console Server and the Web Administration tool. Both of these tools come on the NT 4.0 Server resource kit CD. To install the Remote Console, go into control panel -> network -> services tab -> add -> remote access service, and point to the ..\..\netadmin\rconsole directory […]

Maximum Number of Sockets and FD_SETSIZE

There is a limit on the number of concurrent socket connections that an application can accept in BSD, Windows, and other operating systems. This is set at compile time, but it can be overridden. Here is a discussion of this limitation by Microsoft, and here is further discussion. One application that is sticking this on […]

Tunnelling Through a Gateway With SSH

Here is a diagram of three servers: What we want to do is create a tunnel with SSH so that can go directly to There is no routing between the networks. The box in between is dual-homed and acting as a security buffer between the 10.50.100 and 10.50.101 networks. After we set up […]

Using OS Identification with Nmap

Nmap can be used to fingerprint operating systems. Here is a typical session: [root@srv-1 usr-1]# nmap -O –min_rtt_timeout=6000 Starting nmap 3.70 ( ) at 2006-05-05 12:49 PDT Interesting ports on (The 1656 ports scanned but not shown below are in state: closed) PORT STATE SERVICE 22/tcp open ssh 111/tcp open rpcbind 6000/tcp […]

Changing the IP Address on a Cisco Router With an IP Conflict

If you wish to bring up a Cisco router that has an IP address that conflicts with existing hosts on your network, there are a variety of ways to change it. We just happened to have a crossover network cable sitting on our work bench, and a GNU/Linux host on the LAN with an extra […]

Adding an IP Address to an Interface With Red Hat and CentOS

There is some apparent voodoo on what, exactly, is needed to add an IP address to an interface using Red Hat style scripts. We have tested this on Red Hat Enterprise 3 and CentOS 4, and it appears that the convention is quite forgiving. This makes sense, really, since if you hose up these interfaces, […]

TCP and UDP Service Listing

Here is a text version of /etc/services that might be useful for determining whether a port is being used by a trojan, etc: TCP and UDP Service Listing

Running KeePass Password Management on GNU/Linux with Wine

Managing all of the passwords one needs to know for both personal and job-related security is quite a challenge. KeePass is a password management program for Windows. It is open-source and released under the GPL, which means it is highly likely that this project will stay around in some form. It also appears to use […]

WinSCP Freeware SFTP and SCP client for Windows

WinSCP is a full featured GUI SCP client. This means that communication between the server and the client is encrypted well, unlike FTP or Explorer. WinSCP also includes synchronization options that will help minimize the amount of traffic needed to mirror filesystems. We installed all of the options: Here you can see the array of […]