North American Network Operators Group
Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Re: IOS 12.3(x) Strange service ports open on router

  • From: Iljitsch van Beijnum
  • Date: Fri Apr 09 17:35:21 2004 
On 9-apr-04, at 22:27, Pekka Savola wrote:


Another pet peeve of roughly the same category: when you enable IPv6,
telnet is automatically open to the world (using v6), even if you have
disabled v4 telnet with an access-list.



The vendor refused to believe this is a problem,




Whether or not this is a problem is in the eye of the beholder, but
from what I've seen, this is standard practice with any kind of packet
filter. As far as I know, only hosts.allow-style tcp wrapping is
agnostic about the IP version.



If you want to run a new protocol, you have to configure filters for it
unless you want to go through life unfiltered. That's the way things
work.



It's even worse with FreeBSD: if you firewall it to the teeth in v4 and
disable v6 in the rc.conf, it will still run v6 with link-local
addresses and allow access to the services that are filtered in v4.