diff -Nru net-snmp-5.9+dfsg/debian/changelog net-snmp-5.9+dfsg/debian/changelog
--- net-snmp-5.9+dfsg/debian/changelog	2021-10-07 12:21:20.000000000 +0200
+++ net-snmp-5.9+dfsg/debian/changelog	2021-11-17 14:58:54.000000000 +0100
@@ -1,3 +1,10 @@
+net-snmp (5.9+dfsg-3ubuntu4) jammy; urgency=medium
+
+  * d/p/lp1945960-*: backport patches for the OpenSSL3 transition
+    (LP: #1945960)
+
+ -- Simon Chopin <simon.chopin@canonical.com>  Wed, 17 Nov 2021 14:58:54 +0100
+
 net-snmp (5.9+dfsg-3ubuntu3) impish; urgency=medium
 
   * No-change rebuild to build packages with zstd compression.
diff -Nru net-snmp-5.9+dfsg/debian/patches/lp1945960-configure-static-linking-Fix-SSL-checks.patch net-snmp-5.9+dfsg/debian/patches/lp1945960-configure-static-linking-Fix-SSL-checks.patch
--- net-snmp-5.9+dfsg/debian/patches/lp1945960-configure-static-linking-Fix-SSL-checks.patch	1970-01-01 01:00:00.000000000 +0100
+++ net-snmp-5.9+dfsg/debian/patches/lp1945960-configure-static-linking-Fix-SSL-checks.patch	2021-11-17 14:58:54.000000000 +0100
@@ -0,0 +1,64 @@
+From bd59be8e4e339870a1400f6866a7b73ca11f6460 Mon Sep 17 00:00:00 2001
+From: Giulio Benetti <giulio.benetti@micronovasrl.com>
+Date: Wed, 12 Sep 2018 20:16:39 +0200
+Subject: [PATCH] configure, static linking: Fix SSL checks
+Origin: https://github.com/net-snmp/net-snmp/commit/bd59be8e4e339870a1400f6866a7b73ca11f6460
+
+During checking of DTLS_method, the stub program is linked only with -ssl
+libssl.a lacks some function from -lcrypto:
+RAND_*()
+ERR_*()
+BUF_MEM_*()
+etc.
+and -lz:
+- inflate()
+- deflate()
+
+Append -lcrypto and -lz to LIBS variable when checking DTLS_method.
+
+See also https://sourceforge.net/p/net-snmp/patches/1374/.
+
+Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
+[bvanassche: Edited subject / rewrote this patch]
+
+schopin: Dropped the configure part of the patch as Debian/Ubuntu build
+as it didn't apply cleanly and the packaging uses autoreconf anyway.
+---
+ configure                   | 52 ++++++++++++++++++++++++++++++++++---
+ configure.d/config_os_libs2 | 14 +++++++---
+ 2 files changed, 58 insertions(+), 8 deletions(-)
+
+--- a/configure.d/config_os_libs2
++++ b/configure.d/config_os_libs2
+@@ -302,13 +302,19 @@
+         LIBS="$netsnmp_save_LIBS"
+ 
+         if test x$CRYPTO = x; then
+-            AC_CHECK_LIB([crypto], [EVP_md5], [CRYPTO="crypto"])
+-        fi
++            AC_CHECK_LIB([crypto], [EVP_md5],
++			 [CRYPTO="crypto"; LIBCRYPTO="-lcrypto"], [
++		AC_CHECK_LIB([crypto], [EVP_md5],
++			     [CRYPTO="crypto"; LIBCRYPTO="-lcrypto -lz"], [],
++			     [-lz])
++	    ])
++	else
++	    LIBCRYPTO="-l${CRYPTO}"
++	fi
+ 
+         if test x$CRYPTO != x; then
+             AC_DEFINE(HAVE_LIBCRYPTO, 1,
+                 [Define to 1 if you have the OpenSSL library (-lcrypto or -leay32).])
+-            LIBCRYPTO="-l${CRYPTO}"
+             netsnmp_save_LIBS="$LIBS"
+             LIBS="$LIBCRYPTO"
+             AC_CHECK_FUNCS([AES_cfb128_encrypt]dnl
+@@ -338,7 +344,7 @@
+             LIBS="$netsnmp_save_LIBS"
+         fi
+         netsnmp_save_LIBS="$LIBS"
+-        LIBS="-lssl"
++        LIBS="-lssl $LIBCRYPTO"
+         AC_CHECK_FUNCS([TLS_method TLSv1_method DTLS_method DTLSv1_method]dnl
+                        [SSL_library_init SSL_load_error_strings]dnl
+ 		       [ERR_get_error_all])
diff -Nru net-snmp-5.9+dfsg/debian/patches/lp1945960-Fix-the-build-against-OpenSSL-3.0.patch net-snmp-5.9+dfsg/debian/patches/lp1945960-Fix-the-build-against-OpenSSL-3.0.patch
--- net-snmp-5.9+dfsg/debian/patches/lp1945960-Fix-the-build-against-OpenSSL-3.0.patch	1970-01-01 01:00:00.000000000 +0100
+++ net-snmp-5.9+dfsg/debian/patches/lp1945960-Fix-the-build-against-OpenSSL-3.0.patch	2021-11-17 14:58:54.000000000 +0100
@@ -0,0 +1,30 @@
+From 19e75743173cb8d49d49fd685b8e0249e83cc820 Mon Sep 17 00:00:00 2001
+From: Bart Van Assche <bvanassche@acm.org>
+Date: Wed, 8 Sep 2021 20:39:42 -0700
+Subject: [PATCH] libsnmp: Fix the build against OpenSSL 3.0
+Origin: https://github.com/net-snmp/net-snmp/commit/19e75743173cb8d49d49fd685b8e0249e83cc820
+
+Fixes: https://github.com/net-snmp/net-snmp/issues/343
+---
+ snmplib/snmp_openssl.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/snmplib/snmp_openssl.c b/snmplib/snmp_openssl.c
+index c092a007a..eb4856c57 100644
+--- a/snmplib/snmp_openssl.c
++++ b/snmplib/snmp_openssl.c
+@@ -899,6 +899,11 @@ netsnmp_openssl_cert_issued_by(X509 *issuer, X509 *cert)
+ 
+ 
+ #ifndef NETSNMP_FEATURE_REMOVE_OPENSSL_ERR_LOG
++#ifndef ERR_GET_FUNC
++/* removed in OpenSSL 3.0 */
++#define ERR_GET_FUNC(e) -1
++#endif
++
+ void
+ netsnmp_openssl_err_log(const char *prefix)
+ {
+-- 
+2.32.0
+
diff -Nru net-snmp-5.9+dfsg/debian/patches/series net-snmp-5.9+dfsg/debian/patches/series
--- net-snmp-5.9+dfsg/debian/patches/series	2021-05-26 01:03:31.000000000 +0200
+++ net-snmp-5.9+dfsg/debian/patches/series	2021-11-17 14:58:54.000000000 +0100
@@ -39,3 +39,5 @@
 perl_makefile_man3pods
 lp1912389-libsnmp-Handle-certificate-loading-errors-gracefully.patch
 lp1912389-libsnmp-SSL-Increase-extension-buffer-size-to-preven.patch
+lp1945960-configure-static-linking-Fix-SSL-checks.patch
+lp1945960-Fix-the-build-against-OpenSSL-3.0.patch