Bug #2440

utmp/wtmp/lastlog host field too short

Added by matthiasr almost 4 years ago. Updated almost 4 years ago.

Status:RejectedStart date:10/24/2012
Priority:LowDue date:
Assignee:-% Done:


Target version:-


In <include/utmp.h> the host field for utmp, wtmp and lastlog is set to 16 characters. This has the effect that both IPv6 addresses and the resolved hostnames sshd puts in lastlog are being truncated. It surfaces as truncated host names in the SSH "Last login: <time> from <host>" message on interactive logins.

IPv6 addresses are max. 39 characters long, 45 if you allow for IPv4 compatible notation: http://stackoverflow.com/questions/166132/maximum-length-of-the-textual-representation-of-an-ipv6-address but since there may be hostnames in there it should probably be MAXHOSTNAME (cf. <sys/param.h>).

Although changing the wtmp and lastlogin file format is probably not easy to achieve safely :(


#1 Updated by alexh almost 4 years ago

  • Status changed from New to Rejected

That's what wtmpx, utmpx and lastlogx are for. changing wtmp, utmp and lastlog host field is a no-go as it is pretty much standard (not sure if actual standard).

Also available in: Atom PDF