I'd like to say, that people usially overestimate the power of the firewalls and the necessety of the complex server-based firewalls - and underestimate the importance of the _rules_ they follow to in their labs... I saw a few cases when an expansive PIX firewall was choosen and installed, and a lot of headache created for the innocent users - and nothin was done against the macro-viruses or NT BO trojans... And it's more important to have _any_ firewall than do not have it at all. CISCO CW IOS is just such thing - even usial ACL-s allow to protect network against the usial _network scanners and exploit users_ - and FW ios with the additional protection allow you to have good L2 - L3 and sometimes L4 protection (I mean OSI levels). Through nothing (except the simple wire cutter) can protect against the crazy users inside the company... On Wed, 22 Sep 1999, Stephen Sprunk wrote:
Date: Wed, 22 Sep 1999 10:38:30 -0500 From: Stephen Sprunk <ssprunk@cisco.com> To: "Alex P. Rudnev" <alex@relcom.EU.net>, Gerry McDonald <gerry@injectronics.com> Cc: nanog@merit.edu Subject: Re: your mail
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120 t/120t5/iosfw2/iosfw2_2.htm#xtocid1359543
SMTP Messages
CBAC detects and blocks SMTP attacks (illegal SMTP commands) and notifies you when SMTP attacks occur. Error messages such as the following may indicate that an SMTP attack has occurred:
%FW-4-SMTP_INVALID_COMMAND: Invalid SMTP command from initiator (192.168.12.3:52419)
Looks like it does do that after all...
IOS FW also monitors HTTP, CU-SeeMe, FTP, H.323, NetShow, r-commands, RealAudio, Sun RPC, SQL*Net, StreamWorks, TFTP, VDOLive, and generic TCP/UDP sessions in addition to SMTP. It also protects against fragment attacks, SYN attacks, ACK attacks, and bogus TCP sequence numbers.
Randy: ip inspect name firewall smtp
S
Stephen Sprunk, K5SSS, CCIE#3723 Network Consulting Engineer Cisco NSA Dallas, Texas, USA e-mail:ssprunk@cisco.com Pager: +1 800 365-4578 Empowering the Internet Generation
----- Original Message ----- From: Alex P. Rudnev To: Gerry McDonald Cc: nanog@merit.edu Sent: Wednesday, September 22, 1999 5:37 Subject: Re: your mail
Get IOS FireWall Feauture set, router with the 2 LAN and 2 WAN interfaces, and say _get away_ to the hw vendors.
No doubt, it's possible to enter into IOS if you did not installed access lists on the VTY, keep working some extra services (such as router-based WWW) or so on; but it do not depend of the firewalls at all... And - if you don't need session-level firewall (with the analysing of SMTP content for example) IOS FW feature set is very effective solution.
Aleksei Roudnev, Network Operations Center, Relcom, Moscow (+7 095) 194-19-95 (Network Operations Center Hot Line),(+7 095) 230-41-41, N 13729 (pager) (+7 095) 196-72-12 (Support), (+7 095) 194-33-28 (Fax)
Aleksei Roudnev, Network Operations Center, Relcom, Moscow (+7 095) 194-19-95 (Network Operations Center Hot Line),(+7 095) 230-41-41, N 13729 (pager) (+7 095) 196-72-12 (Support), (+7 095) 194-33-28 (Fax)