cpan> install Net::SSH2
CPAN: Storable loaded ok
Going to read /home/darius/.cpan/Metadata
  Database was generated on Fri, 18 Jan 2008 05:38:15 GMT
Running install for module Net::SSH2
Running make for D/DB/DBROBINS/Net-SSH2-0.18.tar.gz
CPAN: Digest::MD5 loaded ok
CPAN: Compress::Zlib loaded ok
Checksum for /home/darius/.cpan/sources/authors/id/D/DB/DBROBINS/Net-S
+SH2-0.18.tar.gz ok
Scanning cache /home/darius/.cpan/build for sizes
Net-SSH2-0.18/
Net-SSH2-0.18/META.yml
Net-SSH2-0.18/t/
Net-SSH2-0.18/t/Net-SSH2.t
Net-SSH2-0.18/SSH2.xs
Net-SSH2-0.18/README
Net-SSH2-0.18/example/
Net-SSH2-0.18/example/read.pl
Net-SSH2-0.18/MANIFEST
Net-SSH2-0.18/typemap
Net-SSH2-0.18/ppport.h
Net-SSH2-0.18/fallback/
Net-SSH2-0.18/fallback/const-c.inc
Net-SSH2-0.18/fallback/const-xs.inc
Net-SSH2-0.18/Changes
Net-SSH2-0.18/Makefile.PL
Net-SSH2-0.18/lib/
Net-SSH2-0.18/lib/Net/
Net-SSH2-0.18/lib/Net/SSH2/
Net-SSH2-0.18/lib/Net/SSH2/Dir.pm
Net-SSH2-0.18/lib/Net/SSH2/Listener.pm
Net-SSH2-0.18/lib/Net/SSH2/SFTP.pm
Net-SSH2-0.18/lib/Net/SSH2/Channel.pm
Net-SSH2-0.18/lib/Net/SSH2/PublicKey.pm
Net-SSH2-0.18/lib/Net/SSH2/File.pm
Net-SSH2-0.18/lib/Net/SSH2.pm
Removing previously used /home/darius/.cpan/build/Net-SSH2-0.18

  CPAN.pm: Going to build D/DB/DBROBINS/Net-SSH2-0.18.tar.gz

Net::SSH2: using library -L/usr/lib -lssh2 and include path -I/usr/inc
+lude.
Checking if your kit is complete...
Looks good
Writing Makefile for Net::SSH2
cp lib/Net/SSH2/File.pm blib/lib/Net/SSH2/File.pm
cp lib/Net/SSH2/Dir.pm blib/lib/Net/SSH2/Dir.pm
cp lib/Net/SSH2/PublicKey.pm blib/lib/Net/SSH2/PublicKey.pm
cp lib/Net/SSH2/SFTP.pm blib/lib/Net/SSH2/SFTP.pm
cp lib/Net/SSH2/Listener.pm blib/lib/Net/SSH2/Listener.pm
cp lib/Net/SSH2/Channel.pm blib/lib/Net/SSH2/Channel.pm
cp lib/Net/SSH2.pm blib/lib/Net/SSH2.pm
AutoSplitting blib/lib/Net/SSH2.pm (blib/lib/auto/Net/SSH2)
/usr/bin/perl /usr/share/perl5/ExtUtils/xsubpp  -typemap /usr/share/pe
+rl/5.8/ExtUtils/typemap -typemap typemap  SSH2.xs > SSH2.xsc && mv SS
+H2.xsc SSH2.c
cc -c  -I/usr/include -I. -D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PI
+DS -DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEF
+ILE_SOURCE -D_FILE_OFFSET_BITS=64 -O2   -DVERSION=\"0.18\" -DXS_VERSI
+ON=\"0.18\" -fPIC "-I/usr/lib/perl/5.8/CORE"   SSH2.c
In file included from SSH2.xs:11:
ppport.h:3042:1: warning: "PERL_UNUSED_DECL" redefined
In file included from SSH2.xs:8:
/usr/lib/perl/5.8/CORE/perl.h:163:1: warning: this is the location of 
+the previous definition
SSH2.xs: In function ‘XS_Net__SSH2_version’:
SSH2.xs:579: error: ‘LIBSSH2_VERSION_NUM’ undeclared (first use in thi
+s function)
SSH2.xs:579: error: (Each undeclared identifier is reported only once
SSH2.xs:579: error: for each function it appears in.)
make: *** [SSH2.o] Error 1
  /usr/bin/make  -- NOT OK
Running make test
  Can't test without successful make
Running make install
  make had returned bad status, install seems impossible
[download]

I never use cpan. I would manually install the latest libssh2, then manually install the Perl module......perl Makefile.pl, make , make install..... then see what the errors are. It sounds like your libssh2 is too old or has some version/header problem. The active maillist at ssh maillist can probably provide you with an answer, if the above manual installs fail.

---

I'm not really a human, but I play one on earth. Cogito ergo sum a bum

You have to install a libssh2-0 more recent. On ubuntu, you can have it if you had hardy in your source.list (at least for a short time).