Date: 4 Apr 2001 21:06:24 -0000 From: Peter Pentchev <roam@orbitel.bg> To: FreeBSD-gnats-submit@freebsd.org Subject: bin/26359: [PATCH] a minor nit in how netstat detects 'server sockets' Message-ID: <20010404210624.7541.qmail@ringworld.nanolink.com>
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>Number: 26359 >Category: bin >Synopsis: [PATCH] a minor nit in how netstat detects 'server sockets' >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Wed Apr 04 14:10:01 PDT 2001 >Closed-Date: >Last-Modified: >Originator: Peter Pentchev >Release: FreeBSD 4.3-RC i386 >Organization: Orbitel JSCo. >Environment: 4.3-RC FreeBSD 4.3-RC #43: Wed Apr 4 12:58:23 EEST 2001 >Description: The netstat(1) manpage, as well as common sense, says that netstat, when invoked without the -a option, should not show 'server sockets'. What exactly is a server socket? Is it a listening socket, or merely a socket bound to INADDR_ANY on the local side? If the latter, then allow me to disagree; a server could just as well only listen on a couple of the available interfaces. If the former, read on. The netstat(1) in both -stable and -current (actually ALL versions of netstat, ever since it was imported) honors the former definition, as demonstrated by a quick peek around line 190 of src/usr.bin/netstat/inet.c - there are all kinds of checks there, all checking if the local address of the socket is bound to INADDR_ANY. This causes netstat -n to display some server sockets, too :) >How-To-Repeat: Start an inetd listening on port 7200 of a single interface.. [roam@ref5 ~/fbsd/src/usr.bin/netstat]$ inetd -d -a 216.136.204.102 ~/inetd.conf ADD : fodms proto=tcp accept=1 max=0 user=roam group=(null)class=daemon builtin=0x0 server=/usr/bin/true policy="" inetd: fodms/tcp: ipsec initialization failed; in entrust inetd: fodms/tcp: ipsec initialization failed; out entrust inetd: enabling fodms, fd 4 inetd: registered /usr/bin/true on 4 ^Z [1]+ Stopped inetd -d -a 216.136.204.102 ~/inetd.conf The 'normal' netstat, even without -a, shows the new server socket.. [roam@ref5 ~/fbsd/src/usr.bin/netstat]$ netstat -n | fgrep tcp4 tcp4 0 0 216.136.204.102.7200 *.* LISTEN tcp4 0 20 216.136.204.102.22 216.136.204.21.3319 ESTABLISHED A recompiled version, checking against the foreign address, only shows the 'real' client connection (barring non-sgid-kmem kvm errors ;) [roam@ref5 ~/fbsd/src/usr.bin/netstat]$ ./netstat -n | fgrep tcp4 netstat: kvm not available netstat: kvm not available tcp4 0 0 216.136.204.102.22 216.136.204.21.3319 ESTABLISHED ..and just for completeness, here's the inetd.conf used: [roam@ref5 ~/fbsd/src/usr.bin/netstat]$ cat ~/inetd.conf fodms stream tcp nowait roam /usr/bin/true true [roam@ref5 ~/fbsd/src/usr.bin/netstat]$ >Fix: Here's a kind of a workaround, not a real fix - check the foreign address of the socket against INADDR_ANY (a bind() usually produces this kind of socket). I know that a 'more correct' fix would check the state itself for TCP sockets, but for UDP sockets IMHO the correct thing would still be checking the foreign address against INADDR_ANY. Index: src/usr.bin/netstat/inet.c =================================================================== RCS file: /home/ncvs/src/usr.bin/netstat/inet.c,v retrieving revision 1.41 diff -u -r1.41 inet.c --- src/usr.bin/netstat/inet.c 2001/03/15 20:46:04 1.41 +++ src/usr.bin/netstat/inet.c 2001/04/04 20:33:51 @@ -189,17 +189,17 @@ if (!aflag && ( (af == AF_INET && - inet_lnaof(inp->inp_laddr) == INADDR_ANY) + inet_lnaof(inp->inp_faddr) == INADDR_ANY) #ifdef INET6 || (af == AF_INET6 && - IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) + IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) #endif /* INET6 */ || (af == AF_UNSPEC && (((inp->inp_vflag & INP_IPV4) != 0 && - inet_lnaof(inp->inp_laddr) == INADDR_ANY) + inet_lnaof(inp->inp_faddr) == INADDR_ANY) #ifdef INET6 || ((inp->inp_vflag & INP_IPV6) != 0 && - IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) + IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) #endif )) )) >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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