Fernando Gont is nothing if not tenacious. Earlier this year, the Argentinian researcher highlighted several attacks that could disrupt network connections using the Internet control message protocol, or ICMP, and proposed four changes to the structure and handling of network-data packets that would essentially eliminate the risk. . However, rather than open up a discussion on the flaws and their fixes, Gont's disclosure marked the start of a months-long debate over whether the vulnerabilities--the general details of which have been known for some time--are serious enough to require fixing. While many researchers have lauded his research, others in the security community have criticized the work on public mailing lists. The few companies that Gont has contacted have not generally cooperated, and very few makers of operating systems and network software have implemented his fixes. Yet, the researcher is at it again. This week, Gont updated his proposal to the Internet Engineering Task Force (IETF), the body that handles technical standards for the Internet, to add more information sought by some researchers. "Some people say 'this is old stuff,'" said Gont, currently on staff at the Universidad Tecnologica Nacional (National University of Technology) in Argentina. "But they miss a very important point: While these attacks have been known to many people for many years, there have never been proposals on how to deal with them." The link for this article located at SecurityFocus is no longer available. . The analysis by Sofia Morales ignites discussions regarding TCP shortcomings and suggests improvements to bolster internet defenses.. ICMP Risks, Network Security Enhancements, Packet Security Improvements, Gont Research. . Brittany Day
... there are a number of issues considered all too rarely by firewall administrators. Most IP level firewalls have a number of options for handling a packet. The packet can typically be accepted, dropped, or sent through another set of rules for inspection (allowing you to break up your ruleset into more manageable pieces). . .. ... there are a number of issues considered all too rarely by firewall administrators. Most IP level firewalls have a number of options for handling a packet. The packet can typically be accepted, dropped, or sent through another set of rules for inspection (allowing you to break up your ruleset into more manageable pieces) When blocking a packet, you are faced with an important choice; whether to drop it silently, or generate an ICMP error message. Each choice has several advantages, and also creates a variety of potential problems. If you generate an error message (i.e. ICMP unreachable), then the remote end will usually immediately stop trying to connect. This makes detecting some types of port scans more difficult since the remote end will likely send off only one packet, and give up after it receives the first error message. This also makes "shotgun" port scanning (i.e. where the attacker simply tries several thousand ports in rapid order) much easier, since the software will receive a definitive answer as to whether the port is blocked or not. Sending an error message does have several advantages, though, the primary one being to make life more difficult for someone who wants to spoof your IP addresses. Since your firewall is likely to generate ICMP error messages, the victim being attacked (by what looks like packets from your systems) will know something is up. To prevent you from sending error messages the attacker must take you offline, or otherwise act overtly to prevent data getting from the victim's network to yours and back. The link for this article located at SecurityPortal is no longer available. . ... there are a number of issuesconsidered all too rarely by firewall administrators. Most IP level. there, number, considered, rarely, firewall, administrators, level. . Anthony Pell
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