# mbuffer listening only on tcp6



## rbauer_snow (Sep 30, 2011)

I'm trying to use mbuffer as part of a zfs send/recv pipeline between two hosts.  But when I run mbuffer on the receiving host, it apparently is only listening on tcp6, not tcp4:


```
lucy# mbuffer -I 8888
lucy# netstat -an | grep 8888
tcp6       0      0 *.8888                 *.*                    LISTEN

lucy# mbuffer -I :8888
lucy# netstat -an | grep 8888
tcp6       0      0 *.8888                 *.*                    LISTEN

lucy# host lucy
lucy.zzzzzz.zzz has address 10.65.68.108
lucy# mbuffer -I lucy:8888
mbuffer: fatal: unable to resolve address information for expected host 'lucy': Invalid value for ai_flags
```

This is on 8.2-RELEASE p3, mbuffer-2011.01.19.
I verified that /etc/defaults/rc.conf contains 
	
	



```
ipv6_enable="NO"
```

Is this just a configuration issue, or a bug with mbuffer?

Thanks for any help/advice.
Robert


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## MrClayPole (Jan 26, 2017)

Just ran in to the same issue on FreeBSD 11 and FreeBSD 10.3. Seems you need to specify "-4" as a command line to force it to bind to IPv4


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