linux-kernel - Re: [discuss] portmapping sucks

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 24 Jan 2007 19:10:19 -0800
From:	Trond Myklebust <trond.myklebust@....uio.no>
To:	Jan Engelhardt <jengelh@...ux01.gwdg.de>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [discuss] portmapping sucks

On Thu, 2007-01-25 at 00:50 +0100, Jan Engelhardt wrote:
> Hello list,
> 
> 
> I just don't know where else I could send this, it's sooo generic to 
> Linux and UNIX (perhaps blame SUN for inventing portmap?)
> Well, here goes...
> 
> As we all know, mountd and other SUNRPC (I question this invention too) 
> services are at a fixed RPC port number (/etc/rpc) which are mapped 
> to a random TCP/UDP port, and the application doing the mappings is
> portmap. This random TCP/UDP port selection is what makes it suck.
> 
> Already twice in 6 months, it has occurred to me that mountd was 
> assigned to vital TCP ports, among which there was:
> 
> 631/tcp causing
>   - cups could not start up properly
>   - samba went into an infinite loop upon startup trying
>     to access port 631 with IPP
> 
> There are a number of common ports in the 512-1023 range. All 
> obsolescence and meaninglessness aside, there _are_ rather "important" 
> services in that range, ldaps, rtsp, kerberos, rsync, ftps, imaps, just 
> to name a few from /etc/services. This map-to-random-port behavior is a 
> total DoS thing.
> 
> Not starting portmap until boot has finished does not work. Think 
> of importing NFS beforehand (/usr, anyone?). Even if, your admin would 
> be very puzzled if he finds that normally-disabled daemons cannot be 
> started at any later time.
> 
> At best I'd obsolete the whole SUNRPC stuff, do away with portmap (and 
> just use TCP/UDP port numbers already) and have a LOT of code simplified 
> (portmap registration for knfsd, to name a prime example).
> Or at least give it fixed TCP/UDP/etc. port numbers too.

1) What the hell does this have to do with the kernel mailing list?

2) Then assign a bloody port number to mountd, and stick to it. Why do
you think there is a '-p' command line option in the first place?

Trond

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/