Troubleshooting:

1st Command Output:
$ cvs -t -d:ext:address@hidden/cvsroot/libffcall co libffcall
  -> main: Session ID is 100532054BF4182411F
  -> main loop with CVSROOT=/cvsroot/libffcall
  -> safe_location( where=(null) )
  -> open_connection_to_server (:ext:address@hidden/cvsroot/libffcall)
 -> Starting server: rsh -l avneetkhalsa cvs.savannah.gnu.org cvs server 
Permission denied (publickey).
cvs [checkout aborted]: end of file from server (consult above messages if any)

2nd Command Output:

$ ssh -v address@hidden
OpenSSH_5.9p1 Debian-5ubuntu1.1, OpenSSL 1.0.1 14 Mar 2012
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to cvs.savannah.gnu.org [140.186.70.72] port 22.
debug1: Connection established.
debug1: identity file /home/avneet/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/avneet/.ssh/id_rsa-cert type -1
debug1: identity file /home/avneet/.ssh/id_dsa type -1
debug1: identity file /home/avneet/.ssh/id_dsa-cert type -1
debug1: identity file /home/avneet/.ssh/id_ecdsa type -1
debug1: identity file /home/avneet/.ssh/id_ecdsa-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9
debug1: match: OpenSSH_5.9 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1.1
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: RSA 80:5a:b0:0c:ec:93:66:29:49:7e:04:2b:fd:ba:2c:d5
debug1: Host 'cvs.savannah.gnu.org' is known and matches the RSA host key.
debug1: Found key in /home/avneet/.ssh/known_hosts:8
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/avneet/.ssh/id_rsa
debug1: Authentications that can continue: publickey
debug1: Trying private key: /home/avneet/.ssh/id_dsa
debug1: Trying private key: /home/avneet/.ssh/id_ecdsa
debug1: No more authentication methods to try.
Permission denied (publickey).