Date: Mon, 22 Mar 2004 13:32:13 +0200 From: Vasil Dimov <vd@datamax.bg> To: freebsd-questions@freebsd.org Subject: getnameinfo(3) called from sshd finds error in /etc/hosts? Message-ID: <20040322113213.GA14033@sinanica.lg2a.datamax>
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The problem: when trying to login to an sshd server from 172.27.0.83 it
takes more than a minute for the password prompt to appear.
setup on the server machine:
OS: 5.2.1-RELEASE-p3
/etc/resolv.conf
nameserver 192.168.10.253
(does not know anything about 172.27.0.83)
/etc/hosts:
kutelo2 172.27.0.83
/etc/nsswitch.conf:
hosts: files dns
when started `sshd -ddd' sshd stops at the first:
debug3: Trying to reverse map address 172.27.0.83.
for about a minute. There is a second identical message a few lines after
that, but it causes no problems.
As I see the function "sleeping" that long is getnameinfo(3) called from
libssh from canohost.c
So I extracted the code into a separate file tmp.c:
int
main(int argc, char **argv)
{
struct sockaddr_in from;
socklen_t fromlen;
char name[NI_MAXHOST];
int errcode;
fromlen = sizeof(from);
memset(&from, 0, sizeof(from));
from.sin_len = sizeof(from);
from.sin_family = AF_INET;
from.sin_port = htons(2379);
inet_aton("172.27.0.83", &from.sin_addr);
if ((errcode = getnameinfo((struct sockaddr *)&from, fromlen, name,
sizeof(name), NULL, 0, NI_NAMEREQD)) != 0) {
fprintf(stderr, "getnameinfo(): %d\n", errcode);
} else {
name[sizeof(name) - 1] = '\0';
printf("resolved OK: %s\n", name);
}
return 0;
}
which gives:
resolved OK: kutelo2
This is a mystery as the code in canohost.c is exactly the same, but returns
error code EAI_NONAME after more than a minute sending requests to the
nameserver. What work it has to do with the nameserver as 172.27.0.83 is in
/etc/hosts?
Than I changed nsswitch.conf to:
hosts: files [unavail=return] dns
In that case tmp.c's behavior does not change (resolved OK: kutelo2),
but sshd's first call of getnameinfo(3) fails immediately with EAI_NONAME.
It seems that according to this situation kutelo2 entry in /etc/hosts is
corrupted, but tmp.c does not think so, even when started as the sshd user.
Any ideas of what is happening?
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