Bugtraq mailing list archives
Re: Security Problems with Linux 2.2.x IP Masquerading
From: Nigel.Metheringham () VDATA CO UK (Nigel Metheringham)
Date: Tue, 28 Mar 2000 20:45:47 +0100
hdm () SECUREAUSTIN COM said:
The UDP masquerading code only checks the DESTINATION PORT to determine if a packet coming from the external network is to be forwarded inside.
this is due to a number of hosts/services returning UDP from an IP other than that which the original UDP packet went to - for example it is frequently the case that NFS servers just use the interface ip address "closest" to that which the NFS op came from. I'll give this some thought to work out a way of narrowing this hole (I don't think it can be completely closed without causing other problems). However, in general I would not advise the use of UDP masq for a firewalling gateway - since the only thing that people are normally putting through the UDP side is DNS, you are much better advised to put a decent caching name server on the gateway box and block UDP through completely. Nigel. -- [ - Opinions expressed are personal and may not be shared by VData - ] [ Nigel Metheringham Nigel.Metheringham () VData co uk ] [ Phone: +44 1423 850000 Fax +44 1423 858866 ]
Current thread:
- Re: Security Problems with Linux 2.2.x IP Masquerading Nigel Metheringham (Mar 28)
- Re: Security Problems with Linux 2.2.x IP Masquerading Darren Reed (Mar 28)
- Sun Security Bulletin #00194 patrick () PINE NL (Mar 29)