Using Samba to share a folder from a Linux guest with a Linux host in VirtualBox

Question

I have a VirtualBox vm (Slackware 13.1) which runs a samba share. I just moved that vm from a Windows 7 host to a Linux host (Slackware 14.1).

But now I cannot reach the share anymore. Why?

That's the only vm running on the host. The vm uses NAT and port forwarding is the same as it was in the Windows host:

137 > 137
138 > 138
139 > 139
445 > 445

Should I change something on the host?

I'm not sure the ports are properly forwarded, since I got the following from nmap on the host:

root@machine:/home/vboxuser# nmap -sT -O localhost

Starting Nmap 6.40 ( http://nmap.org ) at 2016-06-15 09:26 BRT
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000039s latency).
Not shown: 993 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
37/tcp   open  time
80/tcp   open  http
113/tcp  open  ident
2222/tcp open  EtherNet/IP-1
3306/tcp open  mysql
3389/tcp open  ms-wbt-server
No exact OS matches for host (If you know what OS is running on it, see http://nmap.org/submit/ ).
TCP/IP fingerprint:
OS:SCAN(V=6.40%E=4%D=6/15%OT=22%CT=1%CU=40410%PV=N%DS=0%DC=L%G=Y%TM=5761497
OS:2%P=i486-slackware-linux-gnu)SEQ(SP=106%GCD=1%ISR=108%TI=Z%CI=I%II=I%TS=
OS:A)OPS(O1=MFFD7ST11NW7%O2=MFFD7ST11NW7%O3=MFFD7NNT11NW7%O4=MFFD7ST11NW7%O
OS:5=MFFD7ST11NW7%O6=MFFD7ST11)WIN(W1=AAAA%W2=AAAA%W3=AAAA%W4=AAAA%W5=AAAA%
OS:W6=AAAA)ECN(R=Y%DF=Y%T=40%W=AAAA%O=MFFD7NNSNW7%CC=Y%Q=)T1(R=Y%DF=Y%T=40%
OS:S=O%A=S+%F=AS%RD=0%Q=)T2(R=N)T3(R=N)T4(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%
OS:RD=0%Q=)T5(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)T6(R=Y%DF=Y%T=40%W
OS:=0%S=A%A=Z%F=R%O=%RD=0%Q=)T7(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)
OS:U1(R=Y%DF=N%T=40%IPL=164%UN=0%RIPL=G%RID=G%RIPCK=G%RUCK=G%RUD=G)IE(R=Y%D
OS:FI=N%T=40%CD=S)

Network Distance: 0 hops

OS detection performed. Please report any incorrect results at http://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 13.06 seconds

I was expecting nmap to show 137, 138, 139, 445. Why they are not appearing?

On the guest I see:

PORT    STATE SERVICE
22/tcp  open  ssh
37/tcp  open  time
113/tcp open  auth
139/tcp open  netbios-ssn
445/tcp open  microsoft-ds

And this:

# netstat -ntlup | grep smbd
tcp6       0      0 :::445                  :::*                    LISTEN      1595/smbd
tcp6       0      0 :::139                  :::*                    LISTEN      1595/smbd

And for nmbd:

# netstat -ntlup | grep nmbd
udp        0      0 10.0.2.255:137          0.0.0.0:*                           1600/nmbd
udp        0      0 10.0.2.15:137           0.0.0.0:*                           1600/nmbd
udp        0      0 0.0.0.0:137             0.0.0.0:*                           1600/nmbd
udp        0      0 10.0.2.255:138          0.0.0.0:*                           1600/nmbd
udp        0      0 10.0.2.15:138           0.0.0.0:*                           1600/nmbd
udp        0      0 0.0.0.0:138             0.0.0.0:*                           1600/nmbd