* Joost Kooij (joost@topaz.mdcc.cx) [010712 05:22]: > On Thu, Jul 12, 2001 at 12:24:17AM -0500, will trillich wrote: > > How do you determine WHICH NETWORK SERVICES ARE OPEN (active)? > > Try "netstat -a | grep LISTEN". To see numeric values (instead > > of the common names for services using a particular port) then > > try "netstat -na" instead. For more info, look at "man netstat". > > As root, you can also use the '-p' option to netstat, to display > the process id/name that is attached to the open port. > > > Curious about your NETWORK TRAFFIC? There's a whole bunch of > > ways to monitor it: iptraf, showtraf, netwatch, tcpview, statnet, > > or even > > tcpdump | grep 'what you want to see' > > tcpdump has its own filter, which is much more effective in > terms of resource usage. It actually compiles a filter from > the specification you give it on the command line. > > Example: > tcpdump host foo > tcpdump not port ssh > tcpdump port 53 > tcpdump arp > > > lsof -i | grep 'LISTEN' > > lsof is different from the other tools you mention. It does not > but it does allow matching of internet addresses by protocol, hostname/addr and/or port/servicename (just not state, so you'd have to grep for LISTEN, but not for things like lsof -i tcp or lsof -i @localhost I'm guessing it doesn't make any difference in resource usage, though. Vineet
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