Linux Security Cookbook

NAMEINARGS flag for xinetd 

NAT gateway, canonical client hostname and 

National Infrastructure Protection Center (NIPC) (U.S.) 

    home page 

National Institutes of Health, ÒNetwork and Network Monitoring SoftwareÓ page 

nc command

    -u option (for UDP ports) 

    probing ports with 

netgroups

    customizing shosts.equiv file to restrict hostbased authentication 

    defining 

Netscape, certificate storage 

netstat command

    --all option 

    --inet option (printing active connections) 

    --listening option 

    -e option (adding username) 

    -p option (process ID and command name for each socket) 

    /proc files, reading 

    conversion of IP addresses to hostnames 

    examining network state on your machines 

    printing summary of network use 

    summary for networking on a machine 

network (/etc/init.d startup file) 

network configuration of your systems, attack vulnerability and 

network filesystems

    remote integrity checks 

    searching 

    snooping with filesnarf 

network interfaces 

    bringing up 

network intrusion detection systems (NIDS) 

    attacks against 

    rapid development in 

    Snort  [See Snort]

network monitoring tools

    NIH page 

    web page information on 

network protocols, detecting insecure 

network script 

network services, access control facilities 

network switches, packet sniffers and 

networking

    /proc/net/tcp and /proc/net/upd files 

    disabling for secure integrity checks 

    monitoring and intrusion detection  [See intrusion detection for networks monitoring systems for suspicious activity]

    summary for, printing with netstat 

networks

    access control  [See also firewalls]

        adding a new service (inetd) 

        adding a new service (xinetd) 

        denial-of-service attacks, preventing 

        enabling/disabling a service 

        levels of control 

        listing network interfaces 

        logging access to services 

        prohibiting root logins on terminal devices 

        redirecting connections to another socket 

        restricting access by remote hosts (inetd) 

        restricting access by remote hosts (xinetd with libwrap) 

        restricting access by remote hosts (xinetd with tcpd) 

        restricting access by remote hosts (xinetd) 

        restricting access by remote users 

        restricting access to service by time of day 

        restricting access to SSH server by account 

        restricting access to SSH server by host 

        restricting services to specific directories 

        starting/stopping network interface 

    hacks, system recovery from 

    intrusion detection  [See intrusion detection for networks Snort]

    local activities, examining 

        /proc filesystem 

        lsof command, examining processes 

        printing summary of use with netstat 

    monitoring traffic on 

        observing via GUI 

        searching for strings in 

    protecting outgoing traffic 

        authenticating between SSH2 client and OpenSSH server 

        authenticating between SSH2 server and OpenSSH client with OpenSSH key 

        authenticating between SSH2 server and OpenSSH client with SSH2 key 

        authenticating by public key in OpenSSH 

        authenticating by trusted host 

        authenticating in cron jobs 

        authenticating interactively without password 

        copying files remotely 

        invoking remote programs 

        keeping track of passwords 

        logging into remote host 

        SSH client defaults, changing 

        SSH, using 

        tailoring SSH per host 

        terminating SSH agent on logout 

        tunneling TCP connection through SSH 

    refusal of connections by system logger 

    tracing system calls  2nd 

Newsgroups application (Mozilla) 

NFS  [See network filesystems]

ngrep program 

    -A option, printing extra packets for trailing context 

    -T option (relative times between packets) 

    -t option (timestamps) 

    -X option (searching for binary data) 

    detecting use of insecure protocols 

    download site 

    home page for 

    libcap-format network trace files 

    searching network traffic for data matching extended regular expressions 

NIDS  [See network intrusion detection systems Snort]

nmap command 

    -r option, sequential port scan 

    host discovery, use of TCP and ICMP pings 

    information gathered in network security testing 

    probing a single target 

    running as root 

    scanning range of addresses 

    stealth options, using to test logging and intrusion detection 

    testing for open ports 

        -O option for operating system fingerprints 

        -sU options (for UDP ports) 

        customizing number and ranges of ports scanned 

        port scans 

    testing for vulnerabilities of specific network services 

nmapfe program  2nd 

nmh (mail handler) 

NNTP, tunneling with SSH  2nd 

no_access keyword, xinetd.conf 

non-local mail (acceptance by SMTP server) 

noninteractive commands, invoking securely on remote machine 

NOPASSWD tag (sudo command) 

notice priority, system messages 

null-terminated filenames