Sean Carolan a écrit : > We have an issue with some customers who refuse to accept ICMP traffic > to their mail servers. It seems that they have put Mordac, preventer > of information services in charge of their firewall policy > (http://en.wikipedia.org/wiki/List_of_minor_characters_in_Dilbert#Mordac). > > My mail logs are showing that customers who specifically disallow ICMP > traffic have many "Connection Reset" entries in our logs: > > Oct 14 08:00:50 mailsrv sendmail[2024]: m9ED0Yf5002021: > to=<customername at customer.org>, delay=00:00:16, xdelay=00:00:16, > mailer=esmtp, pri=42476, relay=mail.customer.org. [XX.XX.XX.XX], > dsn=4.0.0, stat=Deferred: Connection reset by mail.customer.org. > > I have disabled pmtu discovery on our routers as well as on all our > outbound mail servers. Is there anything else I can do on our side to > help the situation? Consider setting a small MTU (or MSS, ....) for the borked networks instead of changing your setup globally. something like ip route add 192.0.2.0/24 via 10.0.0.1 mtu 1000