diff -r f9f922fd127d sys/src/cmd/ssh.c
--- a/sys/src/cmd/ssh.c	Mon Apr 20 00:08:35 2020 +0200
+++ b/sys/src/cmd/ssh.c	Mon Apr 20 17:07:11 2020 -0700
@@ -492,6 +492,14 @@
 	static char macalgs[] = "hmac-sha1";	/* work around for github.com */
 	static char langs[] = "";
 
+	if(debug){
+		fprint(2, "%s: %s\n", "client supported kex_algorithms", kexalgs);
+		fprint(2, "%s: %s\n", "client supported encryption algorithms", cipheralgs);
+		fprint(2, "%s: %s\n", "client supported compression algorithms", zipalgs);
+		fprint(2, "%s: %s\n", "client supported mac algorithms", macalgs);
+		fprint(2, "%s: %s\n", "client supported languages", langs);
+	}
+
 	uchar cookie[16], x[32], yc[32], z[32], k[32+1], h[SHA2_256dlen], *ys, *ks, *sig;
 	uchar k12[2*ChachaKeylen];
 	int i, nk, nys, nks, nsig;
@@ -530,21 +538,25 @@
 	}
 	ds = hashstr(recv.r, recv.w-recv.r, ds);
 
-	if(debug){
-		char *tab[] = {
-			"kexalgs", "hostalgs",
-			"cipher1", "cipher2",
-			"mac1", "mac2",
-			"zip1", "zip2",
-			"lang1", "lang2",
-			nil,
-		}, **t, *s;
-		uchar *p = recv.r+17;
-		int n;
-		for(t=tab; *t != nil; t++){
-			if(unpack(p, recv.w-p, "s.", &s, &n, &p) < 0)
-				break;
+	/* See RFC4253 Section 7.1 for descriptions. */
+	char *tab[] = {
+		"kexalgs", "srvhostalgs",
+		"clicipher", "srvcipher",
+		"climac1", "srvmac",
+		"clipzip", "srvzip",
+		"clilang", "srvlang",
+		nil,
+	}, **t, *s;
+	uchar *p = recv.r+17;
+	int n;
+	for(t=tab; *t != nil; t++){
+		if(unpack(p, recv.w-p, "s.", &s, &n, &p) < 0)
+			break;
+		if(debug)
 			fprint(2, "%s: %.*s\n", *t, utfnlen(s, n), s);
+		if(!strcmp(*t,"clicipher") && !strstr(s,cipheralgs)) {
+			fprint(2, "%s not found in %.*s\n", cipheralgs, utfnlen(s, n), s);
+			sysfatal("server does not support cipher");
 		}
 	}
 
@@ -1258,7 +1270,7 @@
 	fprint(fd, "%s\r\n", send.v);
 	recv.v = readline();
 	if(debug)
-		fprint(2, "server verison: %s\n", recv.v);
+		fprint(2, "server version: %s\n", recv.v);
 	if(strncmp("SSH-2.0-", recv.v, 8) != 0)
 		sysfatal("bad server version: %s", recv.v);
 	recv.v = strdup(recv.v);