Le Jeudi 9 Février 2006 22:57, Eric Cooper a écrit : > On Fri, Feb 10, 2006 at 02:17:13AM +0900, Romain Lenglet wrote: > > approx runs as a standalone demon, but does not allow to > > either filter connections according to /etc/hosts.allow and > > /etc/hosts.deny files, nor to bind to a specific address. > > > > Filtering according to hosts_access(5) files should be > > relatively easy, by using the TCP wrapper library (package > > libwrap0). Alternatively, making approx a passive program > > executed by tcpd (inetd) or making it able to bind on one or > > more explicitly specified interfaces would make it better > > from a security viewpoint. > > Thanks, these are good suggestions. I'll look into this for > the next version. Do you have any advice on which approach is > better (more flexible for alternate inetd schemes, or more > secure, or other criteria)?
From the least to the most performant: - start through inetd: inetd parses /etc/hosts.*, and starts a process for every connection, which is very unefficient - use libwrap: like inetd, parse /etc/hosts.* for every established connection - bind to specific addresses: attempted connections to unwanted addresses are refused at the kernel level From the least to the most flexible: - bind to specific addresses: it does filter connection according only to the destination address, and is useful only if the system has several IP addresses and only a subset of those addresses should accept connections - inetd and libwrap: filtering according to source address, service, client user, etc. Impact on design (from low impact to high impact): - start through inetd: you would have to move from a standalone daemon design to a one-process-per-connection design (that's bad) - bind to specific addresses: you would have to add a configuration parameter to specify the interface(s) to bind to - use libwrap: you would only have to add a few library calls in your code So, what I suggest you is to first add calls to libwrap in your code just after every connection is established. It is quite easy to do: just add a call to hosts_ctl(...) after every accept(...). However, I have no clue on how to do that in Ocaml. Then, if you have time ;), add a parameter to the format of approx.conf to specify the address to bind to, and use that parameter as the parameter to bind(...). -- Romain LENGLET Pr. Chiba Shigeru Group Dept. of Mathematical and Computing Sciences Tokyo Institute of Technology
