The problem is, that some programs (which worked fine on Redhat 6.1) leave too many connetcions open to DNS servers. Some of them are apache, xinetd and one talk server. netstat -lap shows: udp 0 0 mail.lap.ttu.ee:2165 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:2164 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:2157 zaphod.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:2156 zaphod.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:2155 mail.lap.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:2154 benjy.cc.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:2153 mail.lap.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:2152 benjy.cc.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:2149 zaphod.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:2147 mail.lap.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:2146 benjy.cc.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:2141 zaphod.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:2140 zaphod.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:2139 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:2137 mail.lap.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:2136 benjy.cc.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:2135 mail.lap.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:2134 benjy.cc.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:2133 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:2132 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:2128 mail.lap.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:2127 benjy.cc.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:2126 zaphod.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:2084 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:2082 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:2081 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:2079 zaphod.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:2078 mail.lap.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:2077 benjy.cc.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:2075 zaphod.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:2074 mail.lap.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:2073 benjy.cc.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1944 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1834 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1828 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1800 zaphod.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1791 mail.lap.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1773 benjy.cc.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1705 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1704 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1701 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1698 zaphod.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:1697 mail.lap.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:1696 benjy.cc.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:1678 zaphod.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1677 mail.lap.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1673 benjy.cc.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1671 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1668 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1666 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1662 zaphod.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1648 mail.lap.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.tt:sa-msg-port benjy.cc.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1644 mail.lap.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1631 benjy.cc.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1579 zaphod.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1548 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1547 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1546 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1533 mail.lap.ttu.ee:domain ESTABLISHED 14621/httpd udp 112 0 mail.lap.ttu.ee:1532 benjy.cc.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1529 zaphod.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1528 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 112 0 mail.lap.ttu.ee:1526 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 112 0 mail.lap.tt:prospero-np zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1502 mail.lap.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1501 benjy.cc.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1494 zaphod.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1493 mail.lap.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1492 benjy.cc.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1475 zaphod.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1474 mail.lap.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1473 benjy.cc.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1462 zaphod.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1460 mail.lap.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1459 benjy.cc.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1458 zaphod.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1457 mail.lap.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1456 benjy.cc.ttu.ee:domain ESTABLISHED 14595/httpd udp 112 0 mail.lap.ttu.ee:1455 zaphod.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1454 mail.lap.ttu.ee:domain ESTABLISHED 14629/httpd udp 112 0 mail.lap.ttu.ee:1453 benjy.cc.ttu.ee:domain ESTABLISHED 14629/httpd udp 112 0 mail.lap.ttu.ee:1452 zaphod.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:1447 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 112 0 mail.lap.ttu.ee:1446 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1443 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1439 mail.lap.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1438 benjy.cc.ttu.ee:domain ESTABLISHED 14621/httpd udp 112 0 mail.lap.ttu.ee:1437 zaphod.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1436 mail.lap.ttu.ee:domain ESTABLISHED 14605/httpd udp 112 0 mail.lap.ttu.ee:1434 benjy.cc.ttu.ee:domain ESTABLISHED 14605/httpd udp 112 0 mail.lap.ttu.ee:1433 zaphod.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1431 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1430 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1429 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1428 mail.lap.ttu.ee:domain ESTABLISHED 14629/httpd udp 112 0 mail.lap.ttu.ee:1427 benjy.cc.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:1426 zaphod.ttu.ee:domain ESTABLISHED 14629/httpd udp 0 0 mail.lap.ttu.ee:1425 mail.lap.ttu.ee:domain ESTABLISHED 14621/httpd udp 112 0 mail.lap.ttu.ee:1424 benjy.cc.ttu.ee:domain ESTABLISHED 14621/httpd udp 112 0 mail.lap.ttu.ee:1423 zaphod.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1402 mail.lap.ttu.ee:domain ESTABLISHED 14621/httpd udp 112 0 mail.lap.ttu.ee:1399 benjy.cc.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1396 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1395 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1394 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 112 0 mail.lap.ttu.ee:1393 zaphod.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1387 mail.lap.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1386 benjy.cc.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1385 mail.lap.ttu.ee:domain ESTABLISHED 14605/httpd udp 112 0 mail.lap.ttu.ee:1384 benjy.cc.ttu.ee:domain ESTABLISHED 14605/httpd udp 112 0 mail.lap.ttu.ee:1383 zaphod.ttu.ee:domain ESTABLISHED 14621/httpd udp 112 0 mail.lap.ttu.ee:1382 zaphod.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1381 mail.lap.ttu.ee:domain ESTABLISHED14595/httpd udp 112 0 mail.lap.ttu.ee:1380 benjy.cc.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1379 zaphod.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1378 mail.lap.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1377 benjy.cc.ttu.ee:domain ESTABLISHED 14621/httpd udp 112 0 mail.lap.ttu.ee:1376 zaphod.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1372 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1371 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 112 0 mail.lap.ttu.ee:1370 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1369 mail.lap.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1368 benjy.cc.ttu.ee:domain ESTABLISHED 14605/httpd udp 112 0 mail.lap.ttu.ee:1367 zaphod.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1363 mail.lap.ttu.ee:domain ESTABLISHED 14595/httpd udp 112 0 mail.lap.ttu.ee:1362 benjy.cc.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1361 zaphod.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1360 mail.lap.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1359 benjy.cc.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1358 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1357 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 112 0 mail.lap.ttu.ee:1356 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 112 0 mail.lap.ttu.ee:1355 zaphod.ttu.ee:domain ESTABLISHED 14621/httpd udp 0 0 mail.lap.ttu.ee:1354 mail.lap.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1352 benjy.cc.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1351 zaphod.ttu.ee:domain ESTABLISHED 14595/httpd udp 0 0 mail.lap.ttu.ee:1350 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1349 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 112 0 mail.lap.ttu.ee:1348 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1344 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 112 0 mail.lap.ttu.ee:1343 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1342 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1341 mail.lap.ttu.ee:domain ESTABLISHED 14594/httpd udp 0 0 mail.lap.ttu.ee:1340 benjy.cc.ttu.ee:domain ESTABLISHED 14594/httpd udp 112 0 mail.lap.ttu.ee:1339 zaphod.ttu.ee:domain ESTABLISHED 14594/httpd udp 112 0 mail.lap.ttu.ee:1337 zaphod.ttu.ee:domain ESTABLISHED 14605/httpd udp 112 0 mail.lap.ttu.ee:1336 mail.lap.ttu.ee:domain ESTABLISHED 14605/httpd udp 0 0 mail.lap.ttu.ee:1335 benjy.cc.ttu.ee:domain ESTABLISHED 14605/httpd etc... mail.lap.ttu.ee, zaphod and benjy are marked as dns servers in network configuration. what's wrong with it? i don't want to restart servers after every fiwe minutes to close such big amount of open connections.
Same problem here: xinet binds to (atleast) 3 ports to domain-name servers present in resolv.conf (one for each server). Fixed by restarting xinetd. I think this occured when a remote host without a name assigned to the IP tried to connect to a service it not had access to (blocked via tcp-wrappers). I have not noticed the same problem with Apache (talk is not enabled). Apache is, however, not configured to do a reverse-name lookup.
in my case apache was configured to perform hostname lookups. if i disabled it, then it was fine, but that't not solution.
Reassigned to glibc
is it possible to fix this problem? i hoped that the patch for glibc fixes it, but it didn't help.
Sure, if I'll be able to reproduce it. So far I have enabled hostname lookups in Apache and could not see any excessive connections to nameservers. One open connection per nameserver is nothing bad if the application (see man gethostbyname), but the netstat output with those httpd connections does not look too healthy. Can you see it e.g. if no DNS server is running on the local machine (and all DNS lookups go to remote nameservers)?
i disabled local nameserver, but it removed only connections to local nameserver... i think that these connection are left open, if an connection to some service (apache, xinetd, ...) is made from a machine which name can not be looked up. there were 3 dns servers in resolv.conf now i removed 2 remote ones and need to wait until some server without a name makes a connection... is it possible to close a connection without restarting a program that made this connection?
This happened to me again. Had atleast 6 established connections to all nameservers in resolv.conf. Apache is not set to do reverse namelookups. xinetd does however do reverse namelookups. Restarting xinetd removes the established connections. The established connections only happen when xinetd can't resolve the connecting hostname. Here I have only seen this happen when the connecting host does not have a name in any DNS. Also calling nslookup to lookup the host does not leave any ports in established mode (even when nslookup is running). The system is running glibc-2.1.94-3 and a 2.2.17 kernel (not RedHat compiled).
I've been able to reproduce this finally and fixed it recently in glibc. It will appear in the next glibc errata.
*** Bug 23712 has been marked as a duplicate of this bug. ***
I believe glibc-2.2-12 fixes this, if not, please reopen.
*** Bug 24790 has been marked as a duplicate of this bug. ***