I have 4 Ubuntu servers at one site. 3 of the computers can browse the Windows network and see all of the Windows computers and the Linux servers running Samba. They are running 18.04 LTS. I have one16.04 LTS 32 bit computer with pretty much the same hardware and software . That computer cannot browse the Windows network nor connect to smb/cifs shares. It also has shares available and all of the other computers can access them. The other computers can see it and can connect to it's shares as can all of the Windows computers. I cannot mount cifs shares testparm runs without error or warnings. smbtree runs, prompts for a password but returns no results. Code: # smbtree Enter root's password nmblookup runs but returns no results. Code: # nmblookup -W ADMINISTRATION -A 192.168.1.2 Looking up status of 192.168.1.2 No reply from 192.168.1.2 smbclient runs but times out with an error. Code: # smbclient -W ADMINISTRATION -U administrator //shylock2/accounting Enter administrator's password: Connection to shylock2 failed (Error NT_STATUS_IO_TIMEOUT) These commands work on all of the other computers. I have iptables running on this computer to do address translation for my block of public ip addresses. I also have port 137 blocked for udp and tcp on the public ip addresses, but I don't think that should effect the private addresses. Code: -A INPUT -s aa.bb.cc.dd/29 -p udp -m udp --dport 137 -j DROP -A INPUT -s aa.bb.cc.dd/29 -p tcp -m tcp --dport 137 -j DROP -A OUTPUT -s aa.bb.cc.dd/29 -p tcp -m tcp --dport 137 -j DROP -A OUTPUT -s aa.bb.cc.dd/29 -p udp -m udp --dport 137 -j DROP Disabling ufw doesn't solve the problem. I haven't found anything in the logs to indicate a problem. -- Rob Steinmetz