FTP/Telnet/Rlogin/rsh/Rexec: These are insecure protocols because they use plain text authentication. This means that when you authenticate to the telnet or ftp server you send your login and password across the network un-encrypted or "in the clear". Data and even the password are transmitted as plain text. In addition to sending the login and password in the clear telnet and ftp also send the data or payload in the clear as well. There are commonly available programs that constantly monitor the network for packets that contains passwords. Preferably, all telnet and rlogin servers and clients should be removed from all machines.
Disable them if not used.
SNMP: Simple Network Management Protocol (SNMP) is a protocol for network management. SNMP lacks any authentication capabilities, which results in vulnerability to a variety of security threats. These include masquerading, modification of information, message sequence and timing modifications, and disclosure. Someone could receive SNMP traps from your machines and manage your network (e.g. bring up/down interfaces, disable packet filtering systems, etc.). Also, IIRC the community string and password are sent in cleartext; some basic packet sniffing could grab both pieces of information.
Disable it if not used .
SMTP-Open Relay: An open relay (sometimes called an insecure relay or a third-party relay) is an SMTP e-mail server that allows third-party relay of e-mail messages. By processing mail that is neither for nor from a local user, an open relay makes it possible for an unscrupulous sender to route large volumes of spam. In effect, the owner of the server -- who is typically unaware of the problem -- donates network and computer resources to the sender's purpose. In addition to the financial costs incurred when a spammer hijacks a server, an organization may also suffer system crashes, equipment damage, and loss of business.
Disable it if not used .
NFS: NFS is a client/server implementation that makes remote disks transparently available on a local client. It utilizes several daemons and configuration files to enable file sharing. By default, this process is all undertaken without any separate authentication, which makes NFS a security risk. NFS runs on the UDP protocol, which is a connectionless protocol because it does not require any acknowledgement of packet delivery.
Disable them if not used .
How to close FTP/SNMP/SMTP: Go to Control Panel-> Add/Remove Programs->Add/Remove Windows Components-
Select FTP and SMTP to disable them:
Select SNMP to disable it:
Disable NFS : Uncheck NFS in the list, if checked and click OK, Next to Finish:
How to disable Telnet: Go to Run->type “Services.msc”-> Look for Telnet in the list->Right click and select Stop: