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Slackware: inetd denial of service vulnerability Print E-mail
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Posted by Team   
Slackware These updates fix a previously hard-coded limit of 256connections-per-minute, after which the given service is disabledfor ten minutes.

[slackware-security]  inetd DoS patched (SSA:2003-251-01)

Upgraded inetd packages are available for Slackware 8.1, 9.0 and
- -current.  These fix a previously hard-coded limit of 256
connections-per-minute, after which the given service is disabled
for ten minutes.  An attacker could use a quick burst of
connections every ten minutes to effectively disable a service.

Once upon a time, this was an intentional feature of inetd, but in
today's world it has become a bug.  Even having inetd look at the
source IP and try to limit only the source of the attack would be
problematic since TCP source addresses are so easily faked.  So,
the approach we have taken (borrowed from FreeBSD) is to disable
this rate limiting "feature" by default.  It can be reenabled by
providing a -R  option on the command-line if desired, but
for obvious reasons we do not recommend this.

Any site running services through inetd that they would like
protected from this simple DoS attack should upgrade to the new
inetd package immediately.

Here are the details from the Slackware 9.0 ChangeLog:
patches/packages/inetd-1.79s-i386-2.tgz:  Disable inetd's (stupid)
  connection limiting code which can actually cause a DoS rather than
  preventing it.  The default connections-per-minute is now unlimited.
  -R 0 also removes limiting (this is now mentioned in the man page as
  well).  Thanks to 3APA3A for reporting this issue.
  (* Security fix *)


Updated package for Slackware 8.1:

Updated package for Slackware 9.0:

Updated package for Slackware -current:


Slackware 8.1 package:
018502403c63b7257b79deea55a51db5  inetd-1.79s-i386-2.tgz

Slackware 9.0 package:
c844eb828e87ec9b263d4a7879a895d8  inetd-1.79s-i386-2.tgz

Slackware -current package:
acf65702ffd747066c2bcd26f28f8ca4  inetd-1.79s-i486-2.tgz


Kill inetd:
# killall inetd

Upgrade using upgradepkg (as root):
# upgradepkg inetd-1.79s-i386-2.tgz

Restart inetd:
# inetd


Slackware Linux Security Team

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