Re: ssh hangs for 5 seconds for a particular machine
On 2015-04-08 23:57:53 +0200, Vincent Lefevre wrote:
> On 2015-04-08 14:27:38 -0600, Bob Proulx wrote:
> > grep "^hosts" /etc/nsswitch.conf
>
> hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4
[...]
> [...]
> 23:54:03 mprotect(0x7f5b92ff3000, 4096, PROT_READ) = 0
> 23:54:03 munmap(0x7f5b96917000, 176499) = 0
> 23:54:03 socket(PF_LOCAL, SOCK_STREAM, 0) = 4
> 23:54:03 fcntl(4, F_GETFD) = 0
> 23:54:03 fcntl(4, F_SETFD, FD_CLOEXEC) = 0
> 23:54:03 connect(4, {sa_family=AF_LOCAL, sun_path="/var/run/avahi-daemon/socket"}, 110) = 0
> 23:54:03 fcntl(4, F_GETFL) = 0x2 (flags O_RDWR)
> 23:54:03 fstat(4, {st_mode=S_IFSOCK|0777, st_size=0, ...}) = 0
> 23:54:03 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f5b96aa9000
> 23:54:03 lseek(4, 0, SEEK_CUR) = -1 ESPIPE (Illegal seek)
> 23:54:03 write(4, "RESOLVE-ADDRESS 140.77.51.8\n", 28) = 28
> 23:54:03 read(4, "-15 Timeout reached\n", 4096) = 20
> 23:54:08 close(4) = 0
> [...]
According to
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=414569
"avahi-daemon: delay on resolving IP addresses when mdns is
specified in /etc/nsswitch.conf"
the 5-second delay shouldn't occur, as this bug was fixed with the
changelog:
* On new installations, do not add "mdns4" to nsswitch.conf, only
"mdns4_minimal [NOTFOUND=return]". This means we can't
perform reverse DNS using mDNS for addresses outside 169.254.x.x and
fe80::/10, but avoids a 5 second delay if such addresses do not
have a PTR record in DNS (Closes: #412714, #414569, #561622 for
new installations).
The "mdns4" in my /etc/nsswitch.conf file occurs after
"mdns4_minimal [NOTFOUND=return]" so that I don't see why I get
the delay.
--
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
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