LinuxQuestions.org - Strange console messages

If you don't need NFS, then disable it, and that goes for every service you don't need. If you don't have business with the host you mentioned, I'd accept the traffic from that host as a probe. Time to tighten security. Promiscuous mode is usually set using a libpcap tool like a sniffer (tcpdump for instance) or an IDS (Snort): "ifconfig <device> -promisc" or add a line "PROMISC="no"" to your /etc/sysconfig/ifcfg-<device>.

I'll unload the usual security reference list here, hope it helps you:
Basic references:
- AUSCERT UNIX Computer Security Checklist (Version 1.1) www.cert.org/tech_tips/AUSCERT_checklist1.1
- Steps for Recovering from a UNIX or NT System Compromise www.cert.org/tech_tips/root_compromise.html
In fact read the whole of http://www.cert.org/tech_tips/
- The CIT Computer Security Handbook: www.cit.nih.gov/security/handbook.html
- Aging stuff from Phrack, good to read back to be sure, like "Unix System Security Issues" www.fc.net/phrack/files/p18/p18-7.html
- SEI stuff like www.sei.cmu.edu/publications/lists.html handling IDS
- Intrusion Detection and Network Auditing on the Internet www.infosyssec.net/infosyssec/intdet1.htm

Top it off with some reading material on security:
- Security tips: www.cert.org/tech_tips/ and www.cert.org/security-improvement/, http://www.securityportal.com/resear...xsecurity.html
- Top ten vulnerabilities: www.sans.org/topten.htm and http://www.cert.org/present/cert-ove...ends/index.htm
- Firewalling: www.infosyssec.net/infosyssec/firew1.htm, www.linux-firewall-tools.com/linux/
- Securing Xwindows: http://www.uwsg.indiana.edu/usail/ex...d/xsecure.html

Basic Linux references:
http://www.sans.org/infosecFAQ/linux/linux_list.htm
- The SANS Reading room: Linux issues (used Google's cache),
- the LASG or Linux Administrator's Security Guide,
- Securing Optimizing Linux RH Edition(1),
- Linux Security HOWTO,
*Linuxsecurity.com have a Quickreference pdf card.
Post-Installation Security Procedures (Linuxjournal)
- Security Quick-Start HOWTO for Linux,
- The Linux-PAM System Administrators' Guide
- Armoring Linux,
- A Short Course on Systems Administration and Security Under Unix(1)
- SAG: The Linux System Administrator's Guide,
- Basics on firewalling: www.linuxdoc.org/HOWTO/Firewall-HOWTO.html
- Basic introduction to building ipchains rules: www.linuxdoc.org/HOWTO/IPCHAINS-HOWTO.html
- Explanation of the Ipchains logformat: logi.cc/linux/ipchains-log-format.php3
- Ipchains log decoder: dsl081-056-052.dsl-isp.net/dmn/decoder/decode.php
- The Iptables HOW-TO: http://people.unix-fu.org/andreasson/index.html
- LQ notes on Linksys security: http://www.linuxquestions.org/questi...007#post157007
- The Unix Auditor's Practical Handbook: http://www.nii.co.in/tuaph.html,
Neohapsis archives: http://www.neohapsis.com
Linux Gazette: http://www.linuxgazette.com
Experts exchange: http://www.experts-exchange.com
Linuxsecurity.com, SecurityFocus.com
Matt's Unix Security Page: http://www.deter.com/unix/
IRIA: http://www.ists.dartmouth.edu/IRIA/k...base/index.htm
E-secure-db Security Information database: http://www.e-secure-db.us/dscgi/ds.p...ollection-1586
eBCVG.com's security portal: http://www.ebcvg.com/info.php
Jay Beale's docs (Bastille-linux/CIS): http://www.bastille-linux.org/jay/se...icles-jjb.html
Snort: IDS Installation with Mandrake 8.2, Snort, Webmin, Roxen Webserver, ACID, MySQL: http://www.linux-tip.net/workshop/id.../ids-snort.htm
Snort: Database support FAQ: http://www.incident.org/snortdb/
How to Build, Install, Secure & Optimize Xinetd: http://www.openna.com/documentations...netd/index.php
Linuxmag: Hardening Linux Systems: http://www.linux-mag.com/2002-09/guru_01.html