Re: sudo slow on DNS lookup, with invalid resolv.conf entries
> Hi.
Hi.
>
> While DNS lookups for localhost are unusual any reasonable configured
> DNS should have no trouble resolving it. Especially since there are OSes
> that try to resolve *everything* by default via including localhost (AIX
> comes to mind).
>
Understand, but disagree with sudo doing DNS lookups. Will fill a bug with
them.
> While you mentioned misconfigured resolv.conf I believe your problem
> lies somewhat deeper than this.
Actually it is deeper. I did not pay that much attention to the strace I
did before.
https://pastebin.com/j0rw5Kgn
10.1.2.9 is the DNS of the company I work for, turned out I had not
connected to the VPN yet by the time i issued the sudo command.
---
connect(6, {sa_family=AF_INET, sin_port=htons(53),
sin_addr=inet_addr("10.1.2.9")}, 16) = 0^M
poll([{fd=6, events=POLLOUT}], 1, 0) = 1 ([{fd=6, revents=POLLOUT}])^M
sendmmsg(6, [{msg_hdr={msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\372\251\1\0\0\1\0\0\0\0\0\0\tlocalhost\vlocaldoma"...,
iov_len=39}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_OOB|MSG_PEEK},
msg_len=39}, {msg_hdr={msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\25\201\1\0\0\1\0\0\0\0\0\0\tlocalhost\vlocaldoma"...,
iov_len=39}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_PEEK},
msg_len=39}], 2, MSG_NOSIGNAL) = 2^M
poll([{fd=6, events=POLLIN}], 1, 5000) = 0 (Timeout)^M
---
resolv.conf is not a symlink to systemd, just a plain file. I explicitly
removed the symlink and created a normal file.
> Specifically I'm interested with:
>
> grep hosts /etc/nsswitch.conf
>
> grep localhost /etc/hosts
>
> Reco
>
Did not touched these, are the default from stretch:
root@localhost:~# grep hosts /etc/nsswitch.conf
hosts: files mdns4_minimal [NOTFOUND=return] dns myhostname
root@localhost:~# grep localhost /etc/hosts
127.0.0.1 localhost
127.0.1.1 localhost
::1 localhost ip6-localhost ip6-loopback
x9p
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