Thank you for repy I have fix it using --with-threads=fork like CC=arm-linux-gcc CFLAGS="-fno-stack-protector" ./configure --prefix=/mnt/dists/stunnel --with-ssl=/mnt/dists/openssl-v1.1.1j --host=arm-linux --disable-fips --with-random=/dev/urandom --with-threads=fork --disable-libwrap --disable-systemd --disable-ipv6 (you maybe delete stack-protector in configure for cannot find libssp error) and commit #include <ctype.h> in common.c for fix __ctype_b_loc can't resolve symbol and delete all realize code int pty_allocate(int *ptyfd, int *ttyfd, char *namebuf) in pty.c for fix symbol 'openpty': can't resolve symbol like this int pty_allocate(int *ptyfd, int *ttyfd, char *namebuf) { return -1; } and compile openssl with no-threads options CC=arm-linux-gcc ./Configure --prefix=/mnt/dists/openssl-v1.1.1j linux-armv4 no-threads enable-tls1_3 no-asm no-async now running successfully EchoLife_WAP /tmp # ./stunnel -help Initializing inetd mode configuration stunnel 5.58 on arm-unknown-linux-gnu platform Compiled/running with OpenSSL 1.1.1j 16 Feb 2021 Threading:FORK Sockets:POLL,IPv4 TLS:ENGINE,OCSP,PSK,SNI cross-compile stunnel latest version with tls1.3 support is so diffcult. It spend my 2 days to fix problem. I do not why no any guide for cross compile for armv7 not andriod I use cross compile tools-chain is here https://toolchains.bootlin.com/downloads/releases/toolchains/armv5-eabi/tarb...