Problems compiling OpenSSH against default version of OpenSSL on Ubuntu 20.04

[manfred-kaiser]

When I try to compile OpenSSH on Ubuntu 20.04 with the default version of OpenSSL, I got following error:

In file included from sshbuf.h:25,
                 from buffer.h:24,
                 from entropy.h:28,
                 from includes.h:174,
                 from ssh-dss.c:26:
ssh-dss.c: In function 'ssh_dss_sign':
ssh-dss.c:79:25: error: dereferencing pointer to incomplete type 'DSA_SIG' {aka 'struct DSA_SIG_st'}
   79 |  rlen = BN_num_bytes(sig->r);
      |                         ^~
make: *** [Makefile:152: ssh-dss.o] Error 1

The reason is, that the installed version of OpenSSL does not support the needed algorithms.

Using the default version of OpenSSL needs some pathes to the used OpenSSH version.

[manfred-kaiser]

This is only an information, if we want to switch to a newer version of openssh and/or openssl