The IBM z/VM TCP/IP PENDINGCONNECTIONLIMIT statement must be properly configured.

From IBM z/VM Using CA VM:Secure Security Technical Implementation Guide

Associated with: CCI-001095

SV-93607r1_rule The IBM z/VM TCP/IP PENDINGCONNECTIONLIMIT statement must be properly configured.

Vulnerability discussion

DoS is a condition when a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded capacity.Managing excess capacity ensures that sufficient capacity is available to counter flooding attacks. Employing increased capacity and service redundancy may reduce the susceptibility to some DoS attacks. Managing excess capacity may include, for example, establishing selected usage priorities, quotas, or partitioning.The PENDINGCONNECTIONLIMIT statement defines the maximum number of half-open connections that are allowed at any given time. When a new half-open connection causes this limit to be exceeded, a random current half-open connection is dropped and a SynFlood denial-of-service attack is declared.

Check content

Examine the “TCP/IP” configuration file. If there is no “PENDINGCONNECTIONLIMIT” statement, this is a finding.

Fix text

Configure the “PENDINGCONNECTIONLIMIT” statement with a value that is less than the “TCBPOOLSIZE”.

Pro Tips

Lavender hyperlinks in small type off to the right (of CSS class id, if you view the page source) point to globally unique URIs for each document and item. Copy the link location and paste anywhere you need to talk unambiguously about these things.

You can obtain data about documents and items in other formats. Simply provide an HTTP header Accept: text/turtle or Accept: application/rdf+xml.