Maybe UDP is filtered in chroot environment. Can you try to capture the network flow?
Jean-Philippe Méthot <jp.met...@planethoster.info>于2019年8月31日 周六上午2:08写道： > Hi, > > I’ve been trying to setup postfix 3.4.6 (ghettoforge.org package) with > dovecot, mailscanner and the mailwatch frontend on a centos 7 (cloudlinux > 7.6) server. > Everything appears to work properly except that, when I setup smtp and > lmtp as chrooted and try to send mail, a curious name resolution error > happen. The exact error is as follow: > > unable to look up host mx.planethoster.net: Device or resource busy > > This is particularly strange considering that to identify the MX of my > domain, it was able to read its zone. Furthermore, if I su to the postfix > user by giving it a login shell, I am able to dig the MX in question. > So, I can resolve the MX when logged in as the user, but postfix can’t for > unknown reasons. Also, the chroot script was run and resolv.conf was > properly copied in /var/spool/postfix/etc and has the proper permissions. > I suspect that some kind of limitation is put on postfix processes in the > chroot jail, but I don’t know where to look and what to look at. Anyone > ever experienced something similar? > > Best regards, > > Jean-Philippe Méthot > Openstack system administrator > Administrateur système Openstack > PlanetHoster inc. > > > > >
